Progress report of the World Health Organization for 1989 (1 September 1988 - 31 August 1989)

Onchocerciasis Control Programme in West Africa Programme de Lutte contre I'Onchocercose en Afrique de I'Ouest JOINT PROGRAMME COMMITTEE Tenth session The Hague- 4 - 7 December la89 SUMMARY VECTOR CONTROL Climatic conditions Aircraft fleet Treated zones ....... Insecticides Resistance Yector control strategy .. Entomological surveillance and evaluation network .... Entomological activities in the western extension zone Results Monitoring of the aquatic environment ....................... EPIDEMIOLOGICAL EVALUATION .......... BIOSTATISTICS AND INFORMATION SYSTEMS INTERDISCIPLTNARY RESEARCH ... Insecticides Transmission experiments L3 identification Studies in Western Guinea Studies in Sierra Leone_....... Community trials of ivermectin Modelling COMITE CONJOINT DU PROGRAMME Burcau du Prcridcnt JPCIO.2 (ocP/PR/8e) ORIGINAL : FRENCH September 1989 Page 3 4 JOINT PROGRAMME COMMITTEE Officc of the Chairman JPC-CCP I IrI Provisional agenda item 6 ONCHOCERCIASIS CONTROL PROGRAMME IN WEST AFRICA PROGRESS REPORT OF THE WORLD HEALTH ORGANIZATION FOR 1989(l September 1988 - 3l August 1989) Table of contents 5 5 5 6 7 7 l0 l0 r3 r5 t7 r9 l9( a I9 20 2l 2t 2l 22 23 JPClO.2 (ocP/PR/8e) Page 2 SOCIOECONOMIC DEVELOPMENT .. ADMINISTRATION AND SUPPORT SERVICES .. Organization and functioning of services Budget and Finance ............... Personnel Transport Supply and Services ........................ Buildings ... TRAINING DEVOLUTION Training Assistance for the preparation of the plans ..... LTAISON ACTIVITIES With the World Health Organization ............ With the Participating Countries With the statutory bodies With the Donors With the aerial spraying contractor With the scientific community With the general public Public relations ...... Internal meetings ......... Collaboration with non-OCP African countries Collaboration with non-governmental organizations (NGOs) 23 24 24 25 25 26 26 26 27 27 27 27 27 27 27 28 28 28 29 29 30 30 30 30 tl , Fig. I Fig.2 Fig. 3 Fig. 4 Fig. 5 Fig. 6 FIGURES IN ANNEX VCU Plan of operations for 1989 Sectors and operational bases in the OCP western extension area Annual transmission potentials in the OCP western extension zone from May 1988 to April 1989 Annual transmission potentials, Nov. 1987 - Oct. 1988 Annual transmission potentials in the southern extension (a) pre-treatment; (b) control from March 1988 to February 1989 Trend in prevalence of infection in holo-endemic villages in the initial OCP area Villages epidemiologically surveyed in the western extension Predicted impact of control: a) Impact of 14 years of vector control b) Recrudescence after premature cessation of vector control c) Recrudescence control with ivermectin I Fig. 7 Fig. 8 3 I, i JPCl0.2 (ocP/PR/89) Page 3 SUMMARY (a) The 1988 rainy season was marked by an exceptional rainfall which led to high discharges in the whole of the Programme area and a greater number of rivers to be treated. The flood-subsidence period came suddenly at the end of 1988 and the dry season was very severe. The 1989 rainy season took off progressively in June-July. (b) Depending on the season, the Programme used between six and eleven helicopters, one or two fixed-wing aircraft and the liaison aircraft. (c) Just as in 1988, the southern extension has been completely under larviciding in 1989. In the western extension, after Mali and Guinea in 1988, Sierra Leone and Senegal have been brought under larviciding in 1989. In the initial area, larviciding was definitively stopped in the whole of Burkina Faso as well as, in the east, in the Niamey sub-sector in Niger, and on the upper course of the Oti in Togo. In the west, the zone where treatment had been interrupted included the lower basin of the Bani in Mali. (d) The same five insecticides continue to be operational (temephos, chlorphoxim, B.t.}l-l4, permethrin and carbosulfan), making it possible to continue with the larvicide rotation strategy according to discharges and seasons. (e) Temephos resistance of the savanna species has spread to almost the whole of the Programme area but it is reversible everywhere except on the lower part of the Comoe and the Bandama. This enables it to be used alternatively with the other insecticides in most of the treated rivers. (f) The entomological evaluation network has been maintained at its 1988 level in the initial area and the southern extension zone despite a reduction of personnel. In the western extension, all the sectors and bases composed of the national teams have been opened and are operational. (g) Entomological activities have been started in all the 24 operational bases in the western extension. Three years'entomological results are already available for Guinea, Mali and Senegal. Everywhere, the hydrological network has been modernized or installed and only some l0 additional radio beacons are yet to be installed in Sierra Leone. (h) Larviciding was on the whole completely satisfactory during the 1988 rainy season and the 1989 dry season with the exception of some treatment failures on the Bandama basin because of the exceptional proliferation of algae which reduced the efficacy of B.t. H-14. With a very few exceptions, transmission has been interrupted or maintained at a very low level in the whole of the Programme area. (i) Larviciding optimization has been improved further in 1989 and despite an increase in the number of flight hours and in the number of litres of larvicides due to the high discharges of 1988, the budgetary limits have been respected for the period under consideration. The monitoring of the aquatic environment was carried out as usual and covered in particular the rivers treated with permethrin or carbosulfan. (j) The Epidemiological Evaluation Unit (EPI) has evaluated the epidemiological situation in the initial Programme area to help decide where and when larviciding could be stopped. The prevalence of infection has already fallen to epidemiologically insignificant level in the majority of follow-up villages. It has treated the high-risk communities with ivermectin and conducted detailed ophthalmological studies. (k) The epidemiological map of the western extension has been completed in collaboration with the national teams. 'l -a JPCl0.2 (ocP/PR/8e) Page 4 (l) The Biostatistics and Information Systems Unit (BIS) has continued with the analysis of the results from ivermectin trial and the epidemiological mapping, the description and prediction of epidemiological trends in the initial Programme area, the detailed analysis of the entomological data for the extensions and the integrated analysis of data for the planning of operations. It is pursuing the training of the personnel of the different units. (m) Applied research concerned, in particular, the study of new insecticides and new for- mulations, the continuation of entomological studies in Sierra Leone, the study of the impact of ivermectin treatment on transmission, identification of vectors, experimental transmissions and modelling. (n) The new approach to the problems of socioeconomic development has led to the redefinition of activities. Two types of activities are undertaken, one in collaboration with the members of the Committee of Sponsoring Agencies (CSA) and the other by the Socioeconomic Development Unit (ECO). The unit is following up the implementation of the studies and development projects recommended by the Hunting Report and gives assistance for the realization of the study on the repopulation of the onchocerciasis areas. Furthermore, it is continuing with the collection of baseline socioeconomic data. (o) As in previous years, the Administration and Support Services Unit has aimed at providing the quality support and services required at reduced costs in spite of the considerable increases in the different costs. The rate of exchange of the US dollar has not varied. Computerization of the budget and finance operations has been completed. (p) Particular emphasis has been laid this year on field and on-the-job training. (q) As part of Devolution, OCP has contributed to the training of nationals of the Participating Countries and helped in the preparation of the plans of Mali and Niger. (r) The Programme continues to inform the Participating Countries, the Donors, the scientific community and the general public about its activities. VECTOR CONTROL l. The main events of the period under consideration were : - an exceptional rainy season in 1988 which led to a considerable increase in VCU activities during this period. However, the entomological results have remained satisfactory and the optimization of the treatments has made it possible to respect the budgetary limitations. - after the southern extension in 1988, the western extension was brought under treatment in 1989, Senegal and Sierra Leone being added to Mali and Guinea which were already under treatment in 1988. Larviciding has been definitively interrupted in approximately 50% of the initial OCP area. - the rotation of the five operational insecticides used alternatively has enabled the problem of temephos resistance of the savanna species to be solved. No new resistance phenomenon has appeared. - the reinvasion phenomenon was reduced considerably at the beginning of the 1989 rainy season because of the treatment carried out in Guinea and Sierra Leone. Only the Baoul6 basin experienced a notable reinvasion in 1989. t I t t' I a) JPCIO.2 (ocP/PR/89) Page 5 Climetic conditions 2. The second half of 1988 was characterized by an exceptional rainfall compared to the past fifteen years. It resulted in high river discharges (25% to more than 1000,6 above those of 1987). 3. The flood-subsidence period came suddenly towards the end of 1988 and the 1988-1989 dry season was highly pronounced. Consequently, for the first half of 1989 the conditions which prevailed were similar to those of the previous years, with low or no discharges for most of the watercourses. Furthermore, compared to the seasonal norms, the temperatures had a general upward trend for the maximum readings and a downward trend for the minimum readings, particularly in the dry savanna areas. 4. The 1989 rainy season started with a delay of some six weeks compared to the normal and the rainfall came progressively because of the slow movement of the Intertropical Convergence Zone towards the southern regions of the OCP area. It was only at the beginning of July that the rainfall spread to the whole of the Programme area. The rains then came with force and regularly, leading to an immediate and considerable flow of the rivers again. Aircraft fleet 5. The number of Hughes 500D and 500E helicopters varied gradually from eleven to eight, from July to October 1988. In January 1989, the helicopters under contract were seven and then six in February. In April and May, the number of helicopters in service rose to seven and then to eleven again with effect from June 1989. These helicopters were distributed as required among the two aerobases, i.e. Kara in the east and Odienn6 in the west. Two Turbo Thrush aircraft were under contract in the 1988 and 1989 rainy season, but only one during the 1988-1989 dry season. The aircraft fleet included also a spare helicopter and a spare fixed-wing aircraft as well as a liaison Cessna 206 aircraft. Treated zones (Fig. l) Initial area 6. All the watercourses in the initial area were maintained under larviciding in I988 with the exception of those located in Burkina Faso between the northern boundary of the Programme and a line following the border with Benin, Togo and Ghana and then passing to the north of Bobo-Dioulasso. The larviciding interruption zone included the lower basin of the Bani in Mali and most of the Niger/Burkina tributaries of the Niger. 7. In 1989, the Comoe, upstream from the confluence with the Leraba, was treated for six weeks in January and February and then larviciding suspended definitively. The main Leraba will only be treated during the reinvasion period and then selectively from August to December to avoid the settlement of blackfly populations in the very important Grechan breeding site. Larviciding has been suspended definitively on the upper Leraba. In the east, the same will apply to the upper basin of the White Volta and the upper course of the Oti in Togo. These larviciding stoppages are decided in accordance with the epidemiological survey results which show the disappearance of onchocerciasis among the inhabitants of these areas. 8. In 1989, the timetable for the resumption of larviciding on the principal basins is similar to that of 1988, while taking into account the time-lag due to the delayed start of the rainy season. t I a JPCIO.2 (ocP/PR/8e) Page 6 Southern extension zone g. The southern extension zone was completely included in the OCP operational area in 19E8. Regular larviciding has been conducted on the Ou6m6 basin in Benin, the Mono and Sio in ,ouihern Togo and the eastern tributaries of the Volta Lake. This southern extension zone wiii again be maintained completely under larviciding in 1989. Western extension zone 10. In 1988, western Mali and Guinea were put under selective and seasonal larviciding becaur'e of: (a) the difficulties encountered during larviciding of western Mali (breeding sites located on the many tributaries and not on the main rivers, whence the impossibility of correet larviciding); (b) the mapping of the endemic areas in the western extension made by the Epidemiological Evaluation Unit (almost-general hypoendemicity in the north, meso- or hyperendemicity in the south); (c) the introduction of mass ivermectin treatment in the only three hyperendemic foci in the north (Bakoye and Tienfala area in Mali, Gambia in Senegal). ll. It was decided, in agreement with the Expert Advisory Comm.ittee, to treat, in 1989, the Gambia basin which does not present particular aerial larviciding difficulties as soon as the larval breeding sites were filled with water. The treatments were started early July. They will mainly cover ihe Senegal section, where most of the breeding sites are found and the disease is hyjerendemic, and to a lesser extent the northern part of the Guinea section, Particularly on the Koulountou. 12. Larviciding in Guinea was started in mid-April 1989, i.e. a month later than in 1988, because of the delay in the rise of the water levels. Only the Niger basin was treated in the S. sirbanum and/or S. soubrense are?$, with the exception of the areas where S- squamosum is greatly dominant. 13. In Sierra Leone, larviciding was started early May. It is the whole area initially concerned with the extension that was brought under treatment (Rivers Bagb6, Bafi, Pampara, Teye, Rokel, Mango, Kaba and Kolente). Larviciding was suspended on the lower Rokel and the Teye at the end of June because of the total disappearance of savanna blackflies. Insecticides 14. The five operational insecticides remained the same during the period under consideration: - Abate or temephos 20% EC (organophosphorus compound) is still employed because of its ease of use, "*..il.rrt carry and harmlessness to the non-target fauna. It is still utilizable alternatively with the other laivicides in most of the foci. Only the areas where resistance has become irreversible are excluded from rotation larviciding with Abate (Bandama and Comoe basin in C0te d'Ivoire). - Chlorphoxim 20% EC (organophosphorus compound) is a very useful insecticide for the average-discharge watercourses but less selective and more difficult to use than Abate. It should also be noted that in 1989, the company Bayer was able to deliver only 60 000 litres of chlorphoxim out of the 80 000 litres ordered since it has been decided to stop the production t f a I ;JPCIO.2 (ocP/PR/8e) Pa;ge 7 of this larvicide. It is therefore important to study right now the possibility of resumption of production of this larvicide or plan for its replacement in 1990 with pyraclofos (see insecticide research). - Permethrin 20% EC (pyrethroid) is the most manageable and least expensive of the larvicides but its toxicity for the non-target fauna does not allow it to be used apart from high discharges. Furthermore its employment should be avoided in areas where massive use of agricultural pyrethroids could let cross-resistance appear. - Carbosulfm 25% EC (carbamate) is also relatively toxic to the non-target fauna and used only at high water. Besides, its high price makes its use very costly. - Bacillus thuringiensis serotype }I-14 (8.t. H-14, biological insecticide) is the most selective (no action on the non-target fauna) and the most promising from the viewpoint of new for- mulations. The present formulations are not sufficiently concentrated and have a greatly reduced carry. This makes the cost of its use quite high because while its price has fallen by more than 40o/o in a yeat, the cost of helicopter flight hours has increased by almost 40% for the new aerial spraying contract coming into force in I990. The search for new formulations should therefore be pursued actively (see insecticide research). Resistance 15. The insecticide susceptibility monitoring results obtained last year confirm those obtained previously. There is a well-established temephos resistance in the lower part of the Comoe and on the Bandama as well as chlorphoxim resistance for the forest species. Chlorphoxim susceptibility has also decreased in the lower part of the Sassandra. Further to the north, a reversible temephos resistance has been observed in the eastern and central areas (Pendjari, Sota, White Bandama). Susceptibility to the other insecticides has remained normal, and the chlorphoxim treatments, among others, have given good results. Three important missions took place in the western extension between September 1988 and March 1989. Temephos resistance was then present on the Tinkisso, the Niger, most of the tributaries on the right bank of the Niger in Guinea (Sankarani, Milo, Niandan), as well as on some watercourses in Sierra Leone (Mongo, Kaba, Bagbe). It should be noted that from the standpoint of cytotaxonomy, the situation in the western extension is changeable and very complex. Thus, resistant and susceptible populations have been found on several rivers (Milo, Mongo, Kaba). Furthermore, temephos treatments were effective where resistance had been noted a few weeks earlier. A new method has been developed for the analysis of the results so as to improve the predictive value of the susceptibility tests, especially for the savanna species treated with temephos. All the data collected so far are being processed and integrated into a data bank. A cytotaxonomic data bank is also being built, which will make it possible to define better the thresholds of resistance and their dynamics in the OCP area according to each cytotype. Vector control strategy Princioles 16. The strategy of rotation of the five insecticides is now applied regularly in the whole of the OCP area according to the rivers and discharges. 17. The rotations are aimed at limiting the risks of resistance while using the different larvicides to the best of their cost/effectiveness/selectivity ratio. { JPCl0.2 (ocP/PR/Ee) Page 8 18. In areas where temephos resistance has not yet appeared, B.t. H-14 is used up to about l0-12 m3/sec. and then replaced by Abate. If the discharge is very high and the entomological situation justifies it, some permethrin cycles can be carried out when the water levels are at their peak. 19. In areas where temephos resistance is latent, it has been planned to use Abate only when it is the most cost-effective, i.e., at high water just after the spate peak. The basic pattern is therefore B.t.H-14 up to 20-25 m3lsec. then chlorphoxim up to 60-70 m3/sec. then permethrin and/or carbosulfan, suspension during the peak of the high-water period then Abate till the discharge falls again to 20-25 m3lsec. if the susceptibility permits it. 20. In the temephos and chlorphoxim resistance areas, only B.t. H-14 /permethrin and/or carbosulfan rotation is realizable but it is relatively costly. It is important in this case to bring the entomological situation as much as possible under control at the beginning of the flood- subsidence period in order to be able to suspend larviciding as long as possible while the discharge decreases from 60 to20-25 m3lsec. and avoid the use of B.t. H-14 when the discharges are high. On the other hand, it is rarely feasible to suspend larviciding during the period of rise in water level because in most of the basins it corresponds to the reinvasion period, be it reinvasion sources or reinvaded areas. 21. Finally, thanks to the teletransmission of hydrological data, treatment postponements are systematically practised during spates. In fact, this type of circumstantial suspension (being practised for two years now) leads to substantial savings. However, there are rivers in which it is difficult to suspend larviciding without taking great risks, for example the Baoul6 (tributary of the Bani), the Bougouriba, the Sissili or, to a lesser degree, the main Sassandra in which the entomological situation grows worse very rapidly in the absence of treatment. Use q[ hvdroloeical data 22. As has just been seen, the use of the hydrological data is technically and economically important for such a control strategy. 23. Since 1987, VCU has therefore actively undertaken a programme of repair or establishment of hydrological networks in Ghana and Sierra Leone. These networks have also been modernized in the whole of the OCP area through the installation of radio beacons in the different Par- ticipating Countries. Moreover, a second hydrological team has been set up in the eastern zone and based in Kara. The hydrological network repair and modernization programme will be completed in 1990 with the installation of some ten additional radio beacons in Sierra Leone. 24. Thanks to data processing, there is ready access now to all the hydrological data as well as to all the insecticide sprayings carried out. This enables the larviciding programme to be established more specifically and judiciously in terms of number of spraying points and dosage. Furthermore, as mentioned above, these data make it possible also to select the appropriate larvicide. The result is the optimization of the treatment circuits and a more rational organization of the supply of aviation fuel and larvicides to the depots in the field. Details q[ ooerations in 1989 25. As mentioned above (see climatic conditions), the 1989 dry season was very severe and during the first months of the year it is 8.t. H-14 that was widely used in the east as well as the west in the areas where larviciding was not stopped for lack of flow or of biting females. However, chlorphoxim was also used on the most important rivers (Oti, Bandama) as well as I a- IJPCl0.2 (ocP/PR/8e) Page 9 Abate in Sierra Leone and on certain tributaries in the eastern zone (Kara and Mo). It is only the lower Bandama in C0te d'Ivoire that posed treatment problems and so chlorphoxim, carbosulfan and finally permethrin were used successively when the discharge became sufficient. 26. As regards the 1989 rainy season, it is still difficult to indicate precisely the treatments that will be made. However, considering the experience gained previously, it is possible to show now the plans for the different zones. Western zone 27. In the initial western zone, the rotation of the five operational larvicides will be made on the basis of the discharges and the resistance situation. Abate will be introduced again in a number of hydrological basins, particularly on the tributaries of the Bani (Baoul6, Banifing I and IV) as well as on the tributaries of the upper Sassandra in Guinea. It will also be used to treat the Gr6chan breeding sites on the Leraba. Its employment in the Sassandra basin will depend on the return of the blackfly strains in this basin to normal susceptibility. 2E. B.t. }J-14 will be widely used as long as possible. All the watercourses it is planned to treat in the initial western zone have received this product at one time or the other: those mentioned above, the Fie and the Atlantic rivers in the zone. As regards permethrin, which is often replaced by carbosulfan, its use will be limited in time to four or six consecutive cycles at most. The lower reaches of the principal rivers: Comoe, Sassandra, Lower Bandama, Lower N'Zi as well as the White Bandama will be treated with this product. It is planned to use it on the lower part of the tributaries of the Bani if the discharges permit it. 29. The Marahou6 will not be treated with this insecticide. On the other hand, after B.t. H-14 and chlorphoxim, carbosulfan will be employed. Besides, the use of the last-mentioned product will be limited to the Sassandra, Comoe and N'Zi basins. 30. Chlorphoxim, the average-discharge insecticide, will be employed sparingly (see Insec- ticides), mainly on the N'Zi and the Marahoue and in a few cycles on the White Bandama and the tributaries of the upper basin of the Sassandra. 31. The operational trials of pyraclofos will be conducted in the White Bandama basin where larviciding will be suspended to this end for four weeks during the rainy season. 32. Voluntary larviciding suspensions are taking place in the initial western zone for ivermectin trials (Tienfala breeding sites on the Niger and River Faya). Furthermore, it has been decided to stop larviciding definitively in a large part of the initial area (see larviciding in initial area). 33. As regards the western extension zone, terms of reference are not available at the moment for Sierra Leone and the Gambia river. For these two zones, it has therefore been planned to put in place sufficient stocks of insecticides, mainly B.t. H-l4 and Abate. 34. For Guinea, because of the latent temephos resistance in practically the whole of the Niger basin, B.t. H- 14 will be used up to the rise in water level and then replaced with Abate for only five to seven cycles before switching over to permethrin. However, a security stock of chlorphoxim will be set up in Kankan in case of immediate or early temephos resistance. As in 1987 and 1988, it is planned to suspend larviciding on most of the rivers between 15 August and the end of September. It has in fact been observed that such a suspension is possible, recolonization of the rivers being extremely slow. Treatments will be resumed as soon as necessary with Abate or chlorphoxim and then B.r. H-14 + JPCl0.2 (ocP/PR/8e) Page l0 Eastern zone 35. Because of the excellent results obtained in the eastern zone in 198E, both in the initial area and in the southern extension zone, the strategy used in 1989 is similar to that of last year. Almost all the rivers were treated with B.t. H-14 and then chlorphoxim. Permethrin will be employed only at high water on the Ou6m6 basin and carbosulfan on the Mono basin. If Abate susceptibility returns to normal, it will be tried to resume treatments at high water with this larvicide in the Sissili-Kulpawn area. Otherwise, chlorphoxim will be used. Entomologicel survellltnce end eveluetlon network 36. The entomological evaluation network remains an important tool for the evaluation of vector control because each week the results of the catches and dissections made at the different checkpoints make it possible to take decisions concerning the continuation or suspension of larviciding on the different reaches. Of course, these results also influence the sequences for the use of the different larvicides in case of failure of ongoing treatments. 37. In spite of the budgetary restraints, the evaluation network should therefore be maintained at its present level (up to l99l for the initial area) because it is extremely risky to stop larviciding and entomological surveillance simultaneously in a zone. Two years of surveillance after the cessation of larviciding seems a reasonable period. 38. In order to solve this problem to the best, in 1988 as in 1989, the staff of the vector control unit has been reduced by about 8% while preserving the evaluation network as much as possible. To do this, all the OCP catching teams, which previously comprised a driver and two vector collectors, are now composed of a driver-vector collector and a vector collector. Moreover, drivers who are not utilized as vector collectors have become driver-mechanics. 39. In t989, as regards the initial area, including the southern extension, the evaluation network comprised five sectors and twenty-two sub-sectors including one seasonal station. In the western extension, this network is composed of the national teams and comprises eight sectors and twenty-four sub-sectors or bases (see following chapter). 40. In 1988-1989 vector surveillance in the initial area and in the southern extension was undertaken in some 177 catching points (as against 195 in 1987). Prospection of pre-adult breeding sites is made classically in the control breeding sites usually visited and have shown good post-spraying results. 41. In the zones in the initial area where larviciding has been stopped because of the disappearance of the parasite reservoir (very Iow or no onchocerciasis prevalence in the pop- ulation), the evaluation network makes it possible to obtain specific information on a possible residual transmission. 42. This evaluation network has been completed by the setting up in Bamako of an important laboratory where it is possible to identify and dissect many blackflies. Two laboratories for the cytotaxonomic identification of larvae, located in Bamako and Kara, make it possible also to study more precisely the phenomenon of resistance of the different cytotypes in collaboration with the five insecticide susceptibility study teams based in different sectors. Entomological activities in the western extension zone 43. The operational bases and sectors mentioned above comprise 317 workers, all of whom are nationals (see Table I and Fig 2), and are at present operational in the five western extension countries: Mali (2 sectors,8 bases), Senegal (l sector,2 bases), Guinea (3 sectors, ll bases), I I IJPCIO.2 (ocP/PR/8e) Page I I Guinea-Bissau (l sector, I base), Sierra Leone (l sector, 2 bases). These bases employ a total of 52 catching and dissection teams which at present cover l7E checkpoints. Each operational base has a radio station which makes possible the regular transmission of results. 44. Eleven new entomology technicians were trained in 1988 for Senegal (4), Guinea (3) and Sierra Leone (4). Among the entomology technicians trained by the Programme, 57 are being used now for entomological surveillance activities: Mali (16), Guinea (28), Senegal (5), Guinea-Bissau (2), Sierra Leone (6). Six medical entomologists trained by the Programme supervise the activities in their respective countries: Mali (l), Guinea (4), Sierra Leone (l). It is planned to train three more medical entomologists and six additional entomology technicians to complete the present personnel in the western extension zone. 45. Regular entomological monitoring activities conducted by the national teams were started in May 1986 in Guinea (Upper Guinea), Senegal and Mali. This has made it possible so far to have, for these three countries and for more than 100 catching points, three years of exploitable entomological data. 46. In middle Guinea the collection of baseline data was started in December 1987 for the Mamou base and in December 1988 for those of Labe and Gaoual. 47. The operational base of Gabu in Guinea-Bissau began to gather its first entomological data in November 1988, while those of Makeni and Kabala in Sierra Leone started entomological surveillance activities in March 1989. 48. For Mali, Senegal and Guinea, a quick analysis of the results of the past "three entomological years" (Fig. 3), shows high transmission potentials in the upper basin of the Niger, on the Bakoye, the upper Faleme, in the Gambia River basin in Senegal, on the upper and lower Baoul6 in Mali, on the upper Bafing in Guinea, on the tributaries of the Bafing in Mali and on some tributaries on the left bank of the Niger. It should, however, be noted that a high percentage of the infective larvae in these zones may be of animal origin (particularly O. ochengi). 49. On the other hand, transmission seems to be low along River Senegal itself as well as on the greater part of the Bafing in Mali and along most of the tributaries on the left bank of the Niger. / :10 E clo t-. Elo.9 +H atzb E 4(, I E (Y) N r,Fl ia \o al t o\6o\ ta)6I t i \o N olra tso\ rarol ri. N N (Y)!C EEE Eggt.E tEV- Ei H ' 9o E rrl\n r-t N(n e t R o\@ o\ (a\o rar- (a ra(a ra r-(a tso\ o\t tr- @ a (\l lrrrGI I .EsBE'SBE;8 E B; HE E :EE z E (.r t ol ro \o N o\6o\ ra GI @ N N @ tN 66 o\ (?) F{ ol @ t-{ N rr N(\l d t<zp oo t{ z (, J s J o EI z E](r, slz o rilJ fril E(n CNtt) tr I gI z =() J H oF t l' JPCl0.2 (ocP/PR/8e) Pa;ge 12 IJPCl0.2 (ocP/PR/8e) Page 13 Results Larvicidine efficacv 50. Larviciding has had a satisfactory efficacy in the whole Programme area. The excellent results obtained during the 1988 rainy season in the initial area, including the southern extension, were presented to the last session of the Joint Programme Committee held in December 1988 in Dakar. 51. Since then, the efficacy of the treatments has been observed for the first six months of 1989 in the whole Programme including the extension zones. 52. It should be noted, however, that larviciding was disrupted on the Bandama basin. Certain treatment failures can be explained particularly by the exceptional abundance and persistence of very great concentrations of algae in this basin (high temperatures and low currents) which resulted in a considerable decrease of the efficacy of B.t. H-14 which is already difficult to apply at low discharges. Some dams also posed problems either by bringing about sudden and unforeseeable variations in discharges (Lower Bandama) or because they make the rivers perennial and constitute artificial breeding sites difficult to treat by helicopter (Marahou6, N'Zi, White Bandama). 53. Finally, a serious handicap was the lack of experienced pilots due to a too rapid turnover of the pilot strength in Odienn6. At the time of the anti-reinvasion larviciding, in May 1989, with the exception of an experienced pilot staying for short periods, the most experienced pilot had less than six months experience in the OCp area. Dvnamics of bitine oooulations and reinvasion control 54. Without going into the details of the results of the 1988 rainy season, it can be recalled that from the viewpoint of blackfly densities, there have been no sudden considerable increases except in the basins where larviciding was suspended voluntarily as well as in the reinvaded reaches on the western boundary of the initial area. Good results were obtained in certain basins where great blackfly densities were observed last year. This is true of the Lower Bougouriba, the Lower Black Volta and the Kulpawn/Sissili. In the Farako, the fly densities were 4.5 times less than those of 1987 despite the absence of treatment for the past two years. 55. In the south-eastern extension zone, the treatments, which were started during the second week of February 1988, have had good results on fly densities both locally and in certain reinvaded areas such as the valley of the Mo and the Kara. 56. Onchocerciasis transmission was interrupted in the greater part of the initial OCP area and in the southern extension during the 1988 rainy season. This interruption concerned all the onchocerciasis foci in Benin and Togo (except the reinvaded areas) as well as those of Niger and Burkina Faso (except Pendie/Dienkoa for the latter country). 57. Likewise, the foci of northern Ghana, and the Volta Region as well as those of northern and central C6te d'Ivoire and eastern Mali were well controlled. 58. As regards 1989, the dry-season entomological results were quite satisfactory up to the appearance of reinvasion in the different basins. 59. The entomological situation on the Leraba is better this year than in 1988 during which a peak of 90 females/man/day was observed at the end of April and early May. JPCl0.2 (ocP/PR/8e) Page 14 60. There was reinvasion on the Bou at the end of April 1989. This can partly be explained by the treatment failures on the Marahou6. 61. The blackfly densities on the Upper Marahou6 and the Banoroni were comparable to those of 1988. It is probable that part of the females caught came from the lower part of the basin in which treatment failures were observed and the other part from elsewhere. In fact, at Kato (Upper Marahou6), five weeks before the reach started flowing blackflies were being caught whose characteristics were those of reinvasion females. 62. The Sassandra does not seem to have been the subject of a significant reinvasion. 63. Reinvasion of the Baoul6 basin resumed this year. The first flies were caught mid-June. Thirty to forty females were caught daily on the Kankelaba towards the end of June. 64. During the Madina Diassa peak, the parous rates were of the order of 70%. It is therefore probable that there was production of a wave of blackflies in the intermittent-flow zones despite ih" ,.r.r-ption of larviciding as soon as the first river flow was observed at one of the six checkpoints scattered along the sensitive zone. The average number of females/man/day, in early iuly, at Madina, pfaOina Diassa and Kankelaba were 20, 58 md 23 respectively with parous rates of 90%, 98% and 99%. 65. It is too early now to draw conclusions concerning the partial success or failure of the anti-reinvasion larviciding conducted in Sierra Leone. 66. Despite the delay in the start of larviciding, Guinea was relatively well controlled before the reinvasion period and seems to be just slightly reinvaded. No peak comparable to that of Madina Diassa was observed even at the key points of Morigbedougou, Sansanbaya, Kouyalaya, Yalawa or Balandougou. 6i. Larviciding has given very good results in Sierra Leone. However, River Kolente at the Guinea border seems to have been reinvaded even before starting to flow on the whole of its length. This reinvasion may be from its tributaries located in the Guinea section or possibly from rivers located farther to the west (Badi). However, this is yet to be proved. It is unlikely that the female peaks observed in mid-June on the Kolente can alone explain the reinvasion of the Baoul6 in the Madina Diassa area which occurred at the end of June. Finally, the savanna female peaks observed in southern Sierra Leone, notably on the Moa, were of a lesser magnitude than in 1988. Here again, it would be premature to draw conclusions on the presumed directions of the 1989 reinvasion. Results on transmission 68. The annual transmission potentials (ATPs) calculated from November 1987 to October 1988 are on the whole very satisfactory (Fig. 4). 69. In comparison with last year, the remarkable results obtained in the southern extension for the first complete year of larviciding should be particularly noted. This larviciding has also had a very considerable effect on the residual ATPs observed last year in northern Togo and northern Benin (Fig. 5). 70. However, some'black spotsn remain but they are of a very unequal importance as regards their impact on the transmission of blinding onchocerciasis in the treated zones. It should, in fact, be stressed that in the eastern zone and particularly in the southern extension area, almost the whole of the residual transmission is due to females of S. squamosum whose breeding sites, located in the mountainous zones at the border between Togo and Ghana, are not treated because t tJPCt0.2 (ocP/PR/8e) Page 15 this species is a very bad vectdr of the savanna strains of O. volvulzs. Likewise, the checkpoint on the Pru, to the west of the Volta Lake, is not representative because treatment was suspended in this zone for a considerable part of the year during the mass ivermectin treatment campaigns(Asubende area). Almost the whole of the residual transmission on the lower Comoe, the N'Zi and the N'Zo is also due to forest females of the S. sanctipauli subcomplex, most coming from untreated zones farther to the south. Only residual transmissions appearing on the Baoul6 basin at the Mali-Guinea border as well as in the Dienkoa area near Bobo-Dioulasso, of course, are from a savanna origin. It can be hoped that in 1989, with the treatment of Guinea and Sierra Leone, the situation will improve in the reinvaded zones in Mali. The Dienkoa area will be treated with ivermectin while ground-based spraying will be made as long as the climatic conditions permit it (difficulty of access to the breeding sites during the rainy season). Administration of ooerations 7l- As regards personnel, as mentioned earlier, while the evaluation network has not been touched in 1989, the number of professional posts has been reduced by four (22 instead of 26 in 1988) and the number of general service posts from 417 to 390. The personnel has therefore been reduced by about 80/o in 1989 despite the additional work related to the participation of VCU in the ivermectin campaigns. 72. With regard to aerial operations, when the period July 1988-June 1989 is compared with that of last year, a marked increase in flight hours, a total of 8470 as against 7l5l in 1987-1988, i.e., an increase of 18.4%, is observed. This increase is due mainly to the heavy rainfall witnessed during the 1988 rainy season as well as to the inclusion of Sierra Leone in the treatment zone of the western extension. However, it should be noted that the number of flight hours in 1988-1989 is still less than that of 1986-1987 (8470 as against 8980) despite the almost complete coverage of the extension areas. With the treatment stoppages in the initial area, a considerable decrease in flight hours is therefore foreseen next year (almost 35% according to the plan of Action and Budget for 1990). Table 2 gives the details of the flight hours utilized in 1987-1988 and 1988-1989 according to type of aircraft and different months of the year. 73. During the same period, July 1988-June 1989, larvicide consumption increased considerably, from {64 961 litres to 588 640 litres, i.e., a rise of 26.5%. The increase is considerable for all the larvicides but particularly for chlorphoxim and permethrin the consumption of which has more than doubled, which clearly indicates that this increase is directly related to the exceptional 1988 rainy season during which the discharges rose by 25% to 100% on average compared to the previous years (see Table 3). Monitoring of the aquatic environment 74. Aquatic monitoring continued in the Programme area and was centered mainly on theprincipal watercourses treated with the least selective larvicides, i.e., permethrin and carbosulfan. For fish fauna, it is carried out by the national teams of Ghana, Guinea, Cote d'Ivoire and Mali under technical services agreements financed by OCP. The VCU specialized team undertakes the monitoring of the entomofauna of the stations selected by the Ecological Group, with the exception of that of Guinea. 75. In anticipation of larviciding in the western zone, prospections were made in Sierra Leone to select monitoring sites and pre-treatment data were collected in collaboration with consultants. tC\l oFEc GI o o\@o\ I Eo\ rrrlQt': F{('!\o to@ln\or- @ ilg$sE$H$$$F5 qot- s o@o\ at\6 o\ q o! t: oq\ !.! 0qc.! n q9 q xFSEESH$$S$p r,1 \a r- t'!1 -B8E6l crd aC6A .rr. Q) .FO o\@o\ a66 o\ r:A .1 qaAq9oql: r,)??r t tt\\atao(\(')Nr <H NHHa(\ld)ri(.l c? Nr\GI Eo\ Ir-6 o\ 9o. Fd)\9o.1 -'!oel =fr '6SXSF-$+oiE q(o(oN .n -qF o .o F o\@ o\ *o\ti d]aqqqqq eoqng3=giss' "d== t: oNF- ts o\ Ir-@ o\ F{ (r) f- ft(DO\rn\Ooqnno\o\(a!ggFn* c) @\ara .a ol E8tAraoo()E = hI)O, o\66 I@6 o\ nqnqd?\olnoqnn9r\ltFl\t\F?n-fO\rOt--N8tsF8S$S$SE€ q r-r- rf,r- 66 o\ r-6 o\ noq9ol',?',?olaq9qn Cat61 6F\Ot\(f)@H\OtOHtiFir-ororaNo@\ao\@\Of-\ rrt.rt(f)!CtN.(l\O ol g \o tro oEIEg,eggEEEFs CI oF JPCl0.2 (ocP/PR/8e) Page 16 IJPCl0.2 (ocP/PR/8e) Page l7 76. The large-scale trials of cyphenothrin (a pyrethroid) showed a particularly pronounced impact of this product on crabs and the non-target entomofauna with an insufficient efficacy on the vector. On the other hand, pyraclofos (an organophosphorus compound) confirmed short-term effects on the invertebrates comparable to those of chlorphoxim. Its toxicity on the fishes is also less than that of permethrin and carbosulfan. An operational trial will be conducted in August-September 1989 with this larvicide. As regards bioresmethrin (a pyrethroid), pr€- liminary short-term tests on the entomofauna seem to show an impact comparable to that of chlorphoxim but other tests are necessary to specify the toxicity level of this candidate larvicide on fish, crustacea and the benthic entomofauna. 77. Research is continuing on the biology of the principal fish species in order to better determine the reproduction periods. This would make it possible to adjust the treatment tactics so as to spare the juveniles and larvae as much as possible and thereby favour recruitment. Tableau 3 : Comparison of larvicide consumption between July 1987-June 1988 and July 1988-June 1989 (Litres) Year Temephos B.t.H-14 Chlor- phoxim Permethrin Carbo- sulfan Total lq87/1q88 - Litres - Percentage 70,705.9 15.20/o 340,797.7 73.30/o 34,976.2 7.5o/o 10,420.6 2.2o/o 8,061 l.7o/o 464,96t.3 (99.9Vo) rq88/lq8q - Litres - Percentage 90,058 15.3o/o 382,738.9 65.0o/o 77,712.6 13.2o/o 25,449.8 4.30/o 12,680.9 2.20/o 588,640.2 ( l00o/o) Difference in litres and in percent- age +19,352.2 27.4% +41,941.) t2.30/o +42,736.4 122.2o/o +15,029.2 t44.2% +4,619.9 57.3o/o +123,678.9 (26.6%) EPIDEMIOLOGICAL EVALUATION 78. During the past year the Epidemiological Evaluation unit (EPI) conducted an extensive survey of the original OCP area, completed the epidemiological mapping of the western extension, undertook the detailed mapping of five areas selected for large scale ivermectin treatment and treated the population of communities with a high risk of developing onchoc- ercal blindness with this drug. The unit also undertook detailed ophthalmological investiga- tions and studied the impact of ivermectin treatment on the eye. Overall, 1025 villages underwent either evaluation or ivermectin large scale treatment in an extremely heavy schedule compared to previous years. 79. In the original OCP area lll villages were surveyed to evaluate the impact of vector control and to help decide where and when larviciding could safely be interrupted. The results of the central area confirm the most optimistic expectations: the prevalence of infec- tion is falling rapidly (Fie.6) and in the majority of the follow-up villages, it has already reached an epidemiologically insignificant level. The only problem areas remain the I0 km stretch of the Dienkoa river in Burkina Faso and the Kulpawn and Kulda rivers in Ghana. The latter areas are particularly important because they are located on a major reinvasion JPCl0.2 (ocP/PR/8e) Page l8 axis. For the first time substantial improvements were registered in the eastern reinvaded area and in the Marahou6 basin in the COte d'Ivoire. 80. The epidemiological map of the western extension was completed. It included informa- tion on 215 randomly sampled villages, 137 not randomly selected villages and 320 villages selected.for detailed mapping of areas where there is a high risk of onchocercal blindness (Fig. Z). This work was accomplished by national teams. The excellent results of the quality control tests of the Guinean, Malian and Senegalese teams have been reported previously; in comparison with the OCP standard, the Sierra Leonean team members' performance was of similar quality. 81. With regard to the distribution and severity of onchocerciasis, the mapping distin- guished five epidemiological patterns. The northern part of the upper Niger basin in 6uinea, the Tienfala area and the lower Bakoye in Mali and a section of the Gambian river in Senegal are very endemic areas with a high risk of onchocercal blindness. Most of Sierra Leone ii also highly endemic. The southern part of the upper Niger basin is highly endemic but there is a low risk of onchocercal blindness. The northern part of Mali and Senegal, Guinea Bissau and the mountain, the north-eastern corner and the pre-forest areas of Guinea have a very low endemicity. The remaining areas of the western extension have been classified as of intermediate endemicity. It is estimated that 1,434,199 people are infected with O. Volvulus out of a rural population of 4,464,183. E2. The epidemiological mapping has allowed the identification of areas where there is a high risk oi onchoceical blindness and where a large scale ivermectin treatment is indicated. In these selected areas, detailed mapping was conducted to target the population to be treated. At present, detailed mapping has been completed in 13 areas. This activity was also accomplished by national teams. 83. Large scale ivermectin treatment was given for the second time in seven community trial areas and for the first time in four additional foci. During the year, 59,690 people out of a census population of l03,ll0 were treated giving a coverage of 57.9%. Since February 1989, the duration of the monitoring of the effect of ivermectin large scale treatment by resident nurses has been reduced from 72 to 36 hours. 84. The ophthalmological activities were concentrated in the western extension zone. Two main activities could be identified and in addition, detailed ophthalmological evaluation of selected communities in two ivermectin trial areas was carried out. 85. In the first activity, villages with high CMFLs were selected for survey with the view of clarifying and defining the pattern of ocular onchocerciasis and the resulting public health importance of certain areas to allow appropriate operational decisions. This consisted of I I villages in Sierra Leone and two villages in Guinea. The results indicate that in Sierra Leone, ttreie is a pattern of ocular onchocerciasis which appears different from what has been described generally in the original Programme area. Detailed analysis of the results is going on. 86. In the second activity, 20 villages with high CMFLs were examined in the Niger and Mafou river basins in Guinea before the start of large scale ivermectin treatment. This activity has the objective to collect baseline data to enable the eventual estimation of the long-term benefit of ivermectin large scale treatment to the populations. t IJPCl0.2 (ocP/PR/8e) Page 19 BIOSTATISTICS AND INFORMATION SYSTEMS 87. The analysis of evaluation and research data has remained one of the major activities of the unit during the past year. Of particular importance were the analysis of the results of the ivermectin trials, the description and forecasting of epidemiological trends in the original OCp area, the epidemiological mapping of the western extension, the detailed analysis of entomological data from selected sites in the extension areas, and the analysis of the results from fly feeding and transmission experiments. Special attention has been given to integral data analysis in support of operational planning. In this work the application of epidemiological modelling has been the outstanding feature (see also research). 88. As a result of the substantial increase in the collected epidemiological and entomological data, particularly the data from the extension areas, data processing came under great pressure and lagged behind during the first months of 1989. This was resolved when several portable computers arrived for the EPI teams and additional staff were trained in data entry and validation. Data from simple epidemiological surveys can now be entered in the computer while in the field and software has been developed to obtain the results of a first analysis while still in the village. 89. Continuous improvement of other computer programmes for data analysis and training of staff in their utilization has enabled the different units to do more routine data analysis themselves. The OCP computer network has been extended and training in word processing and utilization of general purpose programmes has been provided. The available hardware in BIS is currently sufficient for both detailed data analysis and modelling, taking into account that most model simulations are being run during the night. 90. Compared to previous years, considerably more time has been devoted to reporting of results, whether in the form of technical reports, publications in scientific journals or pre- sentations to different meetings. Technical collaboration and exchange of information with other wHo programmes, in particular TDR, has also been intensified. INTERDISCIPLINARY Rf, SEARCH Insecticides 91. Absolute priority is given to research on new insecticides and new formulations. Pyrethroids 92. In 1988, four insecticides, produced by Roussel Uclaf were tested: bioresmethrin, bioallethrin, esbiothrin and esbiol. The first two proved to be twice stronger (100% mortality in gutter at 0.0125 mg/l/10 min) and were therefore selected for further tests in river. At the same dosage, and for a discharge of L5 m3/sec., the effective carry of bioresmethrin was one kilometre. Bioallethrin was less effective, causing a maximum mortality of 95% at double the dose. Considering the important security margin of bioresmethrin for mammals, and its efficacy in the field, it was recommended to conduct carry tests in river at higher discharges as well as a study of its impact on the non-target fauna. 93. The evaluation of cyphenothrin (GokilahtR l0EC. Sumitomo) was continued in 1988. The impact on the non-target fauna was considerable. Cyphenothrin has therefore been rejected as an operational insecticide. JPCl0.2 (ocP/PR/8e) Page 20 Or ganophos phorus compound s : pyraclof os 94. Pyraclofos, a new organophosphorus compound produced by Takeda Ind., showed a good efficacy during gutter trials and small-scale river treatments. At the dose of 0.1 mgll/10 min., the impact on the non-target insects was greater than that of temephos, but less than that of chlorphoxim. The river carry reached three kilometres for a discharge of 5 mS/sec. There seems to be no cross-resistance between pyraclofos and the other organophosphorus insecticides, maybe because of its mode of action which is different. An operational batch of 3000 litres of 20% EC has just been received for operational treatment. Two new samples of experimental formulations will also be tested. Carbamates 95. No new carbamates were tested in 1988-19E9, but FMC has proposed new carbosulfan formulations in order to improve its carry. At the operational dose, carbosulfan has a maximum carry of 15 km, even at high discharge. B.t. H-14 formulations 96. Several new formulations provided by three companies have been tested by the Insecticide Research Unit (IRU) and Institut Pierre Richet (IPR at Bouak6). The purpose of these trials is to develop formulations which would make it possible to reduce the operational dose from 0.72\/ms/sec. to 0.48 l/mt/sec. The samples from two of these firms showed an efficacy, in mini-gutter, of the same order as the previous formulations, but some samples from the third company were three to six times stronger than the present operational formulations. The tests on the formulations of the three companies will be continued in 1989-1990. 97. Because of the high costs of application by helicopter, it would be greatly advantageous for OCP to use formulations stronger than B.r. H-14. Any increase in strength will result in a proportional decrease in ferry costs. The search for improved formulations of B.t. H'14 therefore remains a priority. Operational use ol insecticides 9E. New carry diagrams have been produced in IRU for aerial operations. These diagrams have been prepared according to an insecticide carry model developed recently. The coefficient values of each insecticide are based on existing data from bioassays and river trials. These coefficients can be used in the aerial treatment optimization procedures planned for the second half of 19E9. In order to increase the precision of the model, it is planned to conduct further carry tests on carbosulfan and permethrin, as well as on chlorphoxim if it would be available for a long time. Trrnsmission experiments gg. These experiments were carried out at three different points in the Programme in order to establish the relationship between microfilarial loads in man and the number of potentially infective larvae developing per fly. lO0. Similar patterns were found at each point, even where the adult worms were known to be old, and indicated that as soon as someone becomes positive for microfilariae, he is capable of transmitting the disease, though lightly infected people contribute less than had been previously believed. t IJPCIO.2 (ocP/PR/8e) Pa;ge 2l l0l. This relationship was a key factor in the simulation model developed to help predict the future of the Programme under various combinations of control strategies. L3 Identification 102. Considerable effort was expended to collect microfilariae and learn the techniques of cryopreservation and microinjection to increase the harvest of infective larvae required to accelerate the development of DNA probe technology in order to separate animal from human Onchocerca and thus evaluate properly the effect of any control strategy on transmission. Because such techniques are far from being field applicable, L3 measurements remain the major identification method. Large numbers of L3 O. ochengi, an animal Onchocerca species, were obtained under contract for comparison with O. volvulus infective larvae. Studies in western Guinea 103. Intensive studies were carried out in all the rivers draining the western escarpment of the Fouta Djalon during the height of the rainy season. The main coastal rivers, the Fatala, Kogon and Tinguilinta, were found to be heavily colonized by larval and pupal populations of Konkoure form of S. soubrense while biting females were rare. Studies during the dry season have confirmed this result. Epidemiological surveys have shown hypoendemicity of onchocerciasis. As a result the borders of the western extension can be redrawn to exclude these river basins. Studies in Sierra Leone 104. Intensive studies, combining morphometric, electrophoretic and cytotaxonomic techniques have provided a very detailed knowledge of vector distributions and roles during the late dry/early rainy season in Sierra Leone and this has made it possible to prepare strategies for controlling the main sources of reinvasion and to begin to work out how to control transmission of blinding disease in the country. Distribution of Vector Species 105. All the main species and most of the forms of the S. damnosun s.l. complex have now been found breeding in Sierra Leone. 106. The savanna species, S. sirbanum and S. damnosum s. str., are found on all the main rivers during the late dry season and early rains but are especially common in the north of the country where they colonize the principal rivers for at least six months of the year. Only one river in southern Sierra Leone, the Moa, is colonized extensively by savanna flies but here, as elsewhere where much smaller colonies are found, they rapidly disappear in May. By July, the savanna species are more or less restricted to the Little and Great Scarcies River Basins in the extreme north of the country. 107. As the savanna flies disappear from the south of Sierra Leone with the onset of the main rainy season, forest species of the S. sanctipalrli sub-complex dominate the large rivers with S. squamosum and S. yahense in smaller watercourses, especially in the mountains and forest relics. 108. ,S. soubrense B is restricted to large lowland rivers whereas in the mountains it is replaced by the Menankaya form of S. soubrense. JPCIO.2 (ocP/PR/8e) Page 22 Vectorial Role lO9. Forest species, especially, S. soubrense B, with over 200 head L3s per 1000 parous flies, were ten times more infective than savanna flies (with only 20 headl3s per 1000 parous). S. soubrense were much more infective (3.5% parous infective compared to 0.8% for savanna flies) and had a higher worm load (4.8 L3s per infective fly head compared to 2.2). ll0. S. soubrense B was also shown to be by far the more efficient vector in experimental infections of two geographical strains of Sierra Leone onchocerciasis as well as of a strain of savanna onchocerciasii from Mali. Further work needs to be undertaken on other species in this sub-complex to determine whether they also need to be included as targets for vector control. Ill. S. squamosum and S. yahense showed intermediate infection rates but because they are found in areas where onchocerciasis is rarely a public health problem, it is likely that these species are inefficient vectors in Sierra Leone, as elsewhere in the Programme' Community trials of ivermectin I12. The second round of ivermectin treatment has been completed in all trial areas. On average the treatment coverage was slightly lower than during the first round except in the most endemic villages where ivermectin treatment proved to be very popular. The incidence of reported adverse reactions during the 72 hours' monitoring period had decreased by more than 70% compared to the first treatment round. only three new severe reactions were reported: one was a case of severe symptomatic postural hypotension and the other two were cases of severe dizziness which did not require active treatment. The patients recovered after lying down for a period of time. No deaths were reported which could be attributed to ivermectin treatment' I13. Follow-up skin snip surveys confirmed the important microfilaricidal effect of ivermectin and the mean microfilarial loads in treated patients decreased by more than 96% in all trial areas. However, the subsequent microfilarial repopulation of the skin was significantly faster than had been demonstrated in ctinical trials. In the Asubende area, the mean microfilarial load in treated patients had returned to more than 40% of its pre-treatment level after one year. The dynamics of the microfilarial repopulation of the skin and the eye are being studied in more detail because of their importance for the frequency of treatment and the effect on transmission. ll4. Ophthalmological re-examinations were carried out in six selected communities in the Asubende area and in two in the Milo basin in Guinea before and after the second round of large scale ivermectin treatment in order to determine the effect of large scale ivermectin treatment on the population in the short term. It was found that one year after ivermectin large scale treatment, early onchocercal lesions of the anterior segment of the eye show some regiession whilst on.ho"r*"I eye lesions at the advanced stage of development and lesions of the posterior segment of the eyes remain unchanged. The additional data collected is being analysed. l15. Entomological studies of the effect of large scale ivermectin treatment on O.volvulus transmission have been undertaken in six of the trial areas. However, the evaluation of the effect of ivermectin has been severely hampered by the presence of animal Onchocerca infection in three of the trial areas. Since animal Onchocerca larrvae in the vector are generally indis- tinguishable from O.volvulus larvae it was not possible to obtain reliable estimates of the reduction it o.volvulus transmission after ivermectin treatment in these three areas. This problem did not play a role in the trials of Asubende, Bui and Dienkoa. In Asubende transmission was reduced I tJPCIO.2 (ocP/PR/8e) Page 23 by 70% - 75% for the first three months but rose to around 50% of pre-treatment levels after l2 months. A second treatment round produced similar transmission reductions during the first three months. In spite of these significant reductions, the remaining level of transmission wns still unacceptably high with an ATP in excess of 1000. I16. In the Bui focus the estimated reduction in vector infection levels was in the order of 500/0 - 80% but in the Dienkoa focus it was less than 40%. More detailed investigations in the latter focus, where there is recrudescence of infection, have shown that the population of several isolated homesteads close to the breeding site had not been treated. Furthermore, a six-monthly treatment schedule has been introduced for this focus where detailed transmission studies will continue. Modelling ll7. Modelling has moved into a critical phase of direct relevance for operational planning in the OCP. The transmission model has been quantified, tested and various sensitivity analyses of the most important parameters have been undertaken. Early 1989 a start has been made with using the model for the prospective evaluation of alternative strategies for onchocerciasis control in the OCP. Though further refinement and testing of the model is still required, the results of this work point already at several major conclusions concerning control strategies based on larviciding, ivermectin treatment and combination of these two. ll8. Simulations of the impact of vector control indicate that 14 years of interruption of transmission will reduce the local parasite reservoir to such a low level that recrudescence of the infection is extremely unlikely if larviciding is stopped and the vector is allowed to return(Fig. 8a). Thirteen years appears to be the breakpoint and recrudescence is certain after 12 years of control (Fig. 8b). The simulations have improved the understanding of the risk and dynamics of possible recrudescence and this has clarified the discussion on the technical requirements for devolution. I19. Large scale ivermectin treatment is expected to be highly effective for morbidity control. It should result in a greater reduction in blindness incidence during the first 5-8 years of control than would vector control. On the other hand, it is not an appropriate tool for time limited transmission control in a previously uncontrolled area and its addition to vector control will not allow significant savings to be made in the larviciding operations. However, it has promise as a tool for transmission control in a post vector control situation where there is recrudescence(Fig. 8c) as long as the recrudescence is detected sufficiently early. Further investigation of this last question is currently the priority in epidemiological modelling. SOCIOECONOMIC DEVELOPMENT 120. The new approach to socioeconomic development problems, which was initiated by the Committee of Sponsoring Agencies (CAP) on the recommendation of the Joint Programme Committee (JPC) and the National Onchocerciasis Committees (NOC), has led to a redefinition of the socioeconomic development activities usually carried out by the Programme itself through its Socioeconomic Development unit (ECO). l2l. Now two types of activities are undertaken, one in collaboration with the other members of the Committee of Sponsoring Agencies (CAP) and the other by the unit alone. The first series of activities concerns consultation missions on socioeconomic development following upon the submission of the Hunting Report to the Participating Countries. The objective of these missions is to follow up the arrangements made and the actions taken by the different governments to ensure implementation of the studies and development projects recommended by the report. JPCl0.2 (ocP/PR/8e) Page 24 122. ltalso involved preparations for the start of the second regional study on the recolonization of the areas protected or to be protected from onchocerciasis which is being carried out with the close collaboration of the competent national authorities. 123. COte d'Ivoire, Sierra Leone, Ghana, Burkina Faso, Togo and Mali have been covered as part of these activities 124. Besides, the Unit gives assistance and advice to consultants selected by the \Horld Bank to undertake the study on the recolonization of the onchocerciasis areas. 125. The other activities cover: - collection of baseline socioeconomic data, which was carried out in Sierra Leone at the beginning of the year, and the programming of a similar study in Senegal (Tambacounda Region) for the end of the 1989 farming season; - preparation and organization of the thirteenth NOC meeting, as regards the socioeconomic aspects, with the technicians of the Ministries of Economic Planning and Agriculture/Rural Development of the Participating Countries; - organization of a visit by a four-member Ghana mission to the Volta Valleys Development Authority (AVV) to which ECO gave assistance in the initiative of exchange of experience concerning strategy for the development of the onchocerciasis-protected areas. ADMINISTRATION AND SUPPORT SERYICES Orgenization and functioning of services 126. The Administration and Support Services Unit provides the following support and services to the operational and technical units and sub-units within the Programme area and to the national teams in the countries of the western extension: - Management - Personnel Administration - Budget and Finance - Supplies and services - Transportation - Vehicle repair and maintenance - Building maintenance and utilities - Logistics - Maintenance of the radio network. 127. As in the previous years, but particularly in 1988/1989, being more conscious of the funding gap, the Administration and Support Services Unit sought to provide the required quality support and services to meet the needs of the Programme at reduced costs in spite of important increases in the costs of personnel, supplies and equipment and services. t JPCl0.2 (ocP/PR/Ee) Page 25 128. The costs of the administration of the Programme are shown in the following table: Table 4 - Cost of Administrative services and percentage 1986 1987 1988 US$ USS US$ I Office of the Director Administration and support Services Support costs, Geneva Total Total Budget 0,6 of administration support costs 3,906,685 3,967,892 25,578,409 15.2% I ,401,084 2,276,598 229,003 1,261,515 2,436,607 269,770 1,035,737 2,358,839 251 ,688 3,646,264 27,921,000 l3o/o33,801,273 tl.7% 129. During the period covered by this report, July 1988 to June 1989, the costs of the support and services to OCP increased in average as shown below despite a reduction of 6 Professional and 63 General Service posts: Personnel Services 8o/o Supplies - foreign 6.50/0 Supplies - local 12% Utilities 4o/o Movement and transportation 5o/o 130. It must be noted that the rates of exchange of the US dollar remained stable during the period of the report and averaged 312 CFA to the US dollar, in terms of FCFA, currency mostly used by OCP. l3l. More efforts and resources were invested in 1988/1989 in the training of the local administrative staff, both formally and in-service training, in the fields of language, word and data processing, financial administration, vehicle and equipment repair and maintenance. Budget and Finance 132. The installation of the computer and appropriate programmes to manage all OCP budgetary and financial operations was successfully completed. It now provides the necessary data, as needed, to establish proper controls over commitments and expenditures, to monitor the rates of exchange of various currencies, to adjust commitments and to take more rigorous decisions on activities or proposed commitments, based on accurate information. 133. The present budget is committed and disbursed as proposed in the Plan of Action and Budget for 1989. Already, a surplus of almost US $2,000,000 is foreseen on account of important reductions in the number of flight hours in the western extension, in spite of an anticipated slight increase in the costs of personnel services. Personnel 134. During 1988, 37 posts were abolished, (4 professional and 33 General Service positions). In 1989, a further 5 professional and 63 General Services posts were abolished to conform with the Plan of Action and Budget for 1989. JPCl0.2 (ocP/PR/8e) Page 26 135. Again in 1989, a staff review was conducted with each of the Units to examine the functioni, the duties and the workload of each position with a view to seeking a better utilization of resources and an improved cost-efficiency. Transport 136. During 1988/1989, 326 vehicles were utilized by OCP. These vehicles drove a total of 6,275,000 kilometres and consumed 995,000 litres of fuel. On average, the fleet remained operational at 90% at all times throughout the Programme area, in spite of 32 vehicle accidents, of which 15 occurred in the western extension. 137. New vehicles were acquired for the national teams in the western extension to make them operational. In addition, the vehicle fleet renewal programme by replacement with more efficient diesel-engined vehicles was resumed. The following vehicles were purchased in 1988/1989 at a cost of US $789 270: - Mercedes Trucks 2 - Toyota Hilux 56 - Toyota LC Pick-up BJ 75 4 - Toyota LC-BI 75 8 - Toyota LC-BJ 60 4 Total 74 138. Yehicles considered beyond economical utilization or repair were taken off the road and sold locally through sealed tenders. Thirty two vehicles were sold in 1988 and 34ate still being disposed off in 1989. 139. Sixty one vehicles were made available on loan to the countries of the western extension to provide mobility to the national teams. These vehicles are maintained by the nationals while OCP provides the fuel, the spare parts and the technical supervision. Furthermore, 50 motor bikes were purchased for the national teams. Supply end Services 140. For 1989, approximately US $E,600,000 was devoted to the purchase of supplies and equipment needed by the Programme including US $4 000,000 for larvicides, US $1,500,000 for petroleum products, US $850,000 for vehicles and spare parts and US $ 300 000 for equipment. An amount of about US $5,600,000 will be processed by the Central Purchasing Service in WHO/Gorovor often through tenders, while the share of direct and local purchases, which has increased sizeably, will be about US $3,000,000. l4l. In addition to the amount for the purchase of supplies and equipment about US $420,000 will be disbursed locally for service contracts, such as building maintenance, insurance, utilities and vehicle repair, and other services. Buildings 142. Adust-free computer room, as well as offices have been constructed in Odienn6. Premises rehabilitations have been made for the Guinea and Sierra Leone teams. Since the Bamako garage is no longer available to the Programme, OCP is examining the co-financing of new vehicle maintenance facilities with the Government of Mali. I ,JPCr0.2 (ocP/PR/8e) Page 27 TRAINING 143. The Programme is pursuing its training policy. It awarded five fellowships in 1989 for the obtention of the certificate of special studies in ophthalmology: three to Benin, one to Burkina and one to Mali; the course is run in a Faculty of Medicine in the African region. 144. As in the past, OCP has laid emphasis on field and in-service training (epidemiological evaluation methodology, ivermectin distribution and post-treatment surveillance). Thus, 323 nationals have been trained as follows: Benin 26 Burkina Faso 195 COte d'Ivoire 12 Ghana 12 Guinea 17 Guinea-Bissau 9 Mali l0 Senegal l0 Togo 32 DEVOLUTION Training 145. As mentioned above and as part of Devolution, nationals have been trained by OCP. In future, special emphasis will be laid on training in public health and epidemiology. Assistance for the preparation of the plens 146. This year the Programme has given sustained assistance for the preparation of the plans of devolution of Mali and Niger. Several working and field visits were undertaken in these two countries. LIAISON ACTIVITIES With the lVorld Health Organization 147. The WHO Regional Director for Africa visited the Programme on 2l June 1989. 148. The Programme Director participated in different statutory meetings: - Regional Committee, from 7 to 14 September 1988 in Brazzaville; - Executive Board, from 9 to 20 June 1989 in Geneva; - Subregional Committee, from 27 February to 3 March 1989 in Bamako' - World Health Assembly, from 8 to 20 May 1989 in Geneva. lYith the Participating Countries 149. The thirteenth meeting of the National Onchocerciasis Committees (NOCs) was held in Ouagadougou from 6 to 9 June 1989. It had a particularity this year in that it brought together only technicians from the different Ministries of Health, Economic Planning and Rural Development. The agenda included the OCP progress report, devolution and socioeconomic development. A report has been prepared and will be presented to the current session of the Joint Programme Committee (JPC). 150. The Charge d'Affaires of the Ghana Embassy in Burkina visited the OCP headquarters on 5 January 1989. o JPCl0.2 (ocP/PR/8e) Page 28 l5l. The Minister of Public Health and Population of COte d'Ivoire visited the OCP subsector at Seguela (COte d'Ivoire) on 28 February 1989. 152. The Programme Director was received in audience by: -The Minister of Public Health, Social Affairs and lVomen \Yelfare of Togo on, 9 February l9E9; -The Minister of Health of Sierra Leone on, 9 March 1989; -The Minister of Health of Ghana on, 2l March 1989; -The Minister of Public Health and Social Affairs of Burkina on, lst June 1989; -The Minister of Pubtic Health and Social Affairs of Mali on, l0 July 1989. lVith the stetutory bodies 153. The Ecoloeical Grouo (EG) held its annual session from 2l to 24 February 1989 in Bouak6, C6te d'Ivoire, and the Expert Advisorv Committee (EAC) held its tenth session from 12 to 16 June 1989 in Ouagadougou. The report has been prepared and will be presented to the current session of the Joint Programme Committee. 154. The Committee of Soonsorine Aeencies (CSA) met on 15 and 16 September 1988 in London, 28 November and Ist December 1988 in Dakar, 13 and 14 April 1989 in Washington and 26 and27 July 1989 in London. The reflections of these different sessions will be submitted to the current session of the JPC. 155. Mr Edward V.K. Jaycox, Vice-President of the World Bank for the African Region, visited the Programme headquarters on 25 January 1989. lVith the Donors ,) 156. In the company of the officer responsible for OCP in the lVorld Bank, the Programme Director visited the government authorities of: - Belgium, on 28 March 1989; - Luxembourg, on 29 March 1989; - Austria, on 30 March 1989; - Italy, on 3l March 1989; - United States of America (Congress), on l3 April 1989; - Netherlands, on 23 May l9E9; - Portugal, on 24 May 1989; - South Korea, on 27 June l9E9; - United Kingdom of Great Britain and Northern lreland, on 28 July 1989. \ilith the rerial spraying contrector 157. Two contract review meetings were held with Evergreen Helicopters, from 17 to 19 October 1988 in McMinnville (USA) and on l0 and I I April 1989 in Geneva. t5E. This company has just been awarded the new aerial spraying contract for the period 1990- r992. t a a l t JPCl0.2 (ocP/PR/8e) Pa;ge 29 lYith the scientific community 159. The Programme participated in the following: -Conference on Tropical Medicine and Malaria, from 15 to 25 September l9E8 in Amsterdam (Netherlands); -Informal Consultation on Bacterial Formulations for cost-effective vector control in endemic areas, from 15 to 24 October 1988, in Pondicherry, India; -Meeting of OCP/OCT/TDR subcommittee for monitoring of community trials of ivermectin, from 25 to 27 Jarruary 1989, in Ouagadougou; -Seminar on ivermectin organized by TDR, on 7 and 8 March 19E9, in Geneva; -Mectizan Committee meeting, on l8 and 19 April 1989, in Atlanta (USA); -Conference on Dracunculiasis, I August 1989, in Lagos (Nigeria); -International Epidemiological Association, African Region Conference, T to 12 August 1989, in Harare, Zimbabwe; -Congress of the International Association of Limnology, from 9 to l9 August 1989, in Munich (Federal Republic of Germany). l60. The Programme staff have published l3 articles in international scientific journals. 16l. The Programme was visited by: -Dr Y. Kono from Takeda Chemical Industries, Japan, on 3 and 4 October 1988; -Dr Dull, Dr Campbell and Dr Kingma of the Mectizan Committee, from I to 16 November 1988; -Dr A.D. Gbakima, from Njala University College of Freetown (Sierra Leone), from 12 to 18 December 1988, in Ouagadougou and Bamako; -fifteen trainees from the Pan-African Development Institute-Sahelian West Africa (IPD-AOS), Ouagadougou, on 2 February 1989; -thirty sixth-year students from the Faculty of Medicine of the University of Abidjan, on 7 March 1989, in Bobo-Dioulasso; -eight students from the Ouagadougou Inter-Country School for Rural Development Engineers (EIER), on 23 and 24 April 1989, in Bobo-Dioulasso. -Dr. B.E.B. Nwoke from Imo State University (Nigeria), for training in cytotaxonomy, from 5 to 16 August 1989, in Bamako 162. The Programme Director visited Lunsar Hospital (Sierra Leone) on l0 March 1989. lYith the general public 163. The quarterly news bulletin, nOncho-Newsn is widely distributed as well as an information paper, "Oncho-Information". 164. A special day was devoted to OCP on the occasion of the 42nd World Health Assembly, on 16 May 1989, in Geneva. I65. Films were shown during the Pan-African Cinema and Television Festival (FESPACO), in schools and colleges in Bouak6 and Dabakala (COte d'Ivoire), in Ouagadougou and during OCP statutory meetings and national weeks. Twenty-two video copies of documentary films were offered to visitors. 166. The Director and senior officers of the Programme granted interviews to the BBC and the Sunday Mirror (United Kingdom)as well as the New York Times (USA) . I JPCl0.2 (ocP/PR/8e) Page 30 Public reletions 167. The Documentation Center was visited by 1035 persons and distributed 266 copies of the document "10 years of Onchocerciasis Controln and 6 315 brochures. It lent 204 books,20 aerial photographs, 2l geographic maps and 43 films and video- cassettes. j'he Center has close relations with the documentation centers of wHo, uNDp, uNIcEF, FAo, IpD/Aos, cll-ss and ORSTOM in Ouagadougou and with those of the Ministry of Health and Social Affairs,Ministry of Economic Planning and Cooperation, Ministry of Agriculture, volta valleys Development Authority (AYV), the University Library and the Burkina Faso public Health School. 168. OCP has prepared a new brochure entitled "15 years onn. 169. It contributed to the production of a film by the Netherlands government and the Netherlands Christian Radio and Television Association on onchocerciasis and the activities of OCP in Mali. 170. Merck Sharp and Dohme (MSD) has produced a film "Thousands receive new treatmentfor River Blindness". Internal meetings 17l. The Programme organized internal meetings: -Hydrobiologists'meeting, l9-20 February I9g9, in Bamako; -Research meeting, 20-24 March 1989, in Ouagadougou; -Management Seminar, 5-7 April 1989, in Ouagadougou; -Meeting on entomological evaluation and activities in the sectors andwestern extension zone, 17-19 May 1989, in Ouagadougou; -Insecticide meeting, 25-27 May 1989, in Bouake. Collaboration with non-OCp African countries 172. As part of ivermectin distribution, the Programme Director had a working session on 3lApril 1989 in Lagos, Nigeria, with the Minister of Health and technicians of his Ministry. He held a similar working session with the Minister of Health of Liberia and his collaborators on 16, 17 and 18 August 1989 in Monrovia. Colleboration with non-governmental organizations (NGOs) 173. Still as part of ivermectin distribution, meetings were held: -on I and 2 September 1988, in Ouagadougou, with Christoffel Blindenmission (CBM) of the Federal Republic of Germany, the Royal Commonwealth Society for the Blind(RCSB) of the United Kingdom, Helen Keller International (HKI) of the United States of America; -from 8 to 12 February 1989, in Lome, with CBM; -on 27 and 28 April 1989, in Ouagadougou, with CBM/HKI and International Eye Foundation (IEF) of the United States of America. t a JPC10.2 (ocP/PR/89 ) Page 31 I G lrJ 9 z @ @ o t j o I I I I I I I I z tr uJ- - --o-' F<oUUcirl J z 9 F cE C o zcUF6 U Uo U2 oN z Y(r J d] ;a q l 8s o 3 z I(9 t I J = t I I I +- t I 1 -l It ) I I (D J J + -'l I I I l I I I I I I I I I I I I I I I ,.1 '-t I I t I I I ! 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