Report of OCP activities and the entomological results in the Niger tributaries basin in Benin: 1978-1998

1WORLD HEALTH ORGANIZATION AFRICAN REGION ORGANISATION I\4ONDIALE DE LA SANTE REGION DE L'AFRIQUE ONCHOCERCIASIS CONTROL PROGRAMME IN WEST AFRICA PROGRAMME DE LUTTE CONTRE L'ONCHOCERCOSE EN AFRIQUE DE L'OUEST B.P. 549 OUAGADOUGOU, Burkina Faso T6169r . ONCHO OUAGADOUGOU T6l. 34 29 53 -3429 59 - 3429 60 Telex ONCHO 5241 BF Fax: 34 2875 Original. English REPORT OF OCP ACTIVITIES AND THE ENTOMOLOGICAL RESULTS IN THE NIGER TRTBUTARTES BASrN rN BENrN (1978-1998) Samuel A. SOWAH* Under contractual service agreement with OCP The report was reviewed under contractual service agreement with OCP by Dr Hyacinthe AGOUA* with the collaboration of the Programme Director and the Chiefs of Units. No t22t02NCUtTEC/3.9 +Medical Entomologists. Previously WHO-Oncho control Programme staff members. By 30-07-02 Ouagadougou, June 2002 2CONTENTS I. INTRODUCTION 2. OVERVIEW OF THE ONCHOCERCIASIS CONTROL PROGRAMME IN WEST AFRICA DESCRIPTION OF THE NIGER TRIBUTARIES BASIN AREA IN BENIN ENTOMOLOGTCAL ACTMTIES (EVALUATION AND VECTOR CONTROL) 3 4 4.1. 4.1.t 4.1.2 4.1.3 4.2. 4.2.1 Aa1A.L.L 4.2.3 4.3. 4.3.1 4.3.2 iaa+.J.J Entomological surveillance. Breeding points. Catching points. Entomological prospections. History on larviciding. Aerial larviciding. Ground larviciding. Insecticides used (lnsecticides rotation) Entomological results. Vectors concerned. Parasites concemed. Transmission. 5 6 SURVEILLANCE OF AQUATIC FAUNA EPIDEMIOLOGICAL EVALUATIONS 6.1 Epidemiological results before vector control. 6.2. Epidemiological results during vector control. 6.3. Latestepidemiologicalresults. 7. IVERMECTINDISTRIBUTION. 8. SOCIOLOGICALINVESTIGATIONS. 9. POPULATIONS SENSITIZATION AND MOBILIZ ATION ACTIVITIES 10. DISCUSSIONS. 11. CONCLUSION 3 1. INTRODUCTION This report is written as a result of contractual service agreement entered into by OCP with the author The aim of this report is to give a consolidated account of OCP activities in the Niger Tributaries basin in Benin as well as the results obtained from the beginning of OCP activities to the end of vector control operations in the basin. The report should cover not only entomological activities but also all aspect of OCP activities such as, epidemiological investigations carried out (with their corresponding results), Ivermectin distribution, sociological investigations if any, sensitisation carried out by OCP field staff, and any other relevant information available. 2. OVERVIEW OF THE ONCHOCERCIASIS CONTROL PROGRAMME IN WEST AFRICA The Onchocerciasis Control Programme in West Africa started its activities in 1974 and covered 7 countries (Benin, Burkina Faso, C6te d'Ivoire. Ghana, Mali, Niger and Togo). Its original savannah area covered 654,000 km2. This was the area where the severe form of onchocerciasis resulting in blindness prevailed leading to the depopulation of the valleys. Following the extension of the Programme activities in C6te d'Ivoire in 1978-1979,the Programme area covered764,000 km2, which represents about i8,000 kms of rivers treated. In view of the good results obtained and in order to prevent reinvasion, further extensions were made southwards and westwards in 1987-1988. Currently, the Programme concerns 11 countries (Benin, Burkina Faso, COte d'Ivoire, Ghana, Guinea, Guinea-Bisau, Mali, Niger, Senegal, Sierra Leone and Togo) and covers 1.300,000 krn'?1fig. t;. The Programme aimed at controlling onchocerciasis to ensure that this disesase is no longer a public health issue. or an obstacle to socio-economic development, and also that countries involved are able to perpetuate this realisation. On the administrative level, the Head Office of the Onchocerciasis Control Programme is based in Ouagadougou, Burkina Faso and includes the Administrative Unit, the Planning, Evaluation and Transfer Unit, and the Vector Control Unit. On the operational level, the Vector Control Unit is divided into two (Eastern and Western) zones with sectors. sub-sectors and operations bases which communicate through a radio network, which allows a rapid transmission of epidemiological data as well as scientific and administrative directives. In 1990. there were 5 sectors.20 sub-sectors and one antenna in Bandiagara, Mali in the original OCP area and its southern extension. The western extension counts 8 sectors and 25 operations bases. The Administration Board is the Joint Programme Committee (JPC) that includes representatives of programme countries, Sponsoring Agencies and delegates of 23 Donor Organisations and Countries. The Committee of Sponsoring Agencies (CSA) is composed of the World Health Organisation (WHO) that is the implementing Agency of the programme, the Food and Agriculture Organisation (FAO) the United Nations Development Programme (UNDP) and the World Bank. 4 As from the mid-9Os, a certain number of sectors, sub-sectors and operations bases were closed down due to the gradual reduction of some programme activities in view of the satisfactory results obtained in most river basins. OCP activities will end on 31 December 2002. 3. DESCRIPTION OF THE TRIBUTARIES OF THE NIGER RIVER BASIN AREA The Tributaries of the Niger basin in Benin cover the North - eastern part of the country (Benin). The basin lies within longitudes 2 degrees east and 4 degrees east, and within latitudes 10 degrees north and 12 degrees 30 minutes north; (fig. 1). This area lies in a typical savannah vegetation belt. There is no rain forest in the basin area However riverine tree galleries can be seen near the sources of the three main rivers of the basin. The climatic conditions in the basin are those of the savannah types, namely, the rainy season and the dry season. The rainy season starts in the basin around mid May to mid June, depending on the year in question. The monthly total rainfall is between a minimum of 50mm to a maximum 400mm with peak in September. The rainy season ends around mid or end of October. This ushers in the Harmattan, which marks the beginning of the dry season. There are three main rivers, which constitute the basin. These are - l. Mekrou (on the western end of the basin area), 2. Alibori (in the middle of the basin area). and 3. Sota (lying at the eastern end of the basin). These three rivers are not perennial. They flow in the rainy season with peak flow around mid August to mid September. They almost dry up in the dry season (from November to mid May or mid June). Among the three the Sota is usually the last river to dry up in the dry season. Some amount of flow can usually be observed even around late February or early March. The major part of the basin area lies in the Sudan Savannah vegetation zone. Only a small area (the water heads of the Alibori and those of the tributaries of the Sota) lies in the Guinea Savannah zone (Walsh et al 1979). 3.1. Mekrou The Mekrou is about 330 km long, namely from its source to the confluence with the Niger. The Mekrou takes its source from water table of the Wemou, the Oueme and the Perma near a village called Findara. The Mekrou becomes the frontier between Benin and Burkina Faso at about 40km downstream of Keremou catching point. After 30km of frontier with Burkina, the Mekrou then becomes the frontier between Benin and the Republic of Niger. The period of flow on the Mekrou is between weeks 27 to 50, with the maximum flow weeks 39 and 40. The discharge on the Mekrou can reach a maximum of 120 cubic metres per second. This rnaximum discharge was recorded in 1993. See graphs on discharges; (fig. 2 and3). The Mekrou has very few tributaries, which are important for Simulium breeding 3.2. Alibori The Alibori is not as long as the Mekrou. From its source to the confluence with the Niger is about 280km long. The Alibori takes its source from a village town called Tobre. 5 The period of flow on the Alibori is between weeks 20 to 50, with the maximum flow between weeks 34 to 40. The discharge on the Alibori can reach a maximum of over 300 cubic metres per second, which was recorded in week 36 in 1994 (fig. 4). 3.3. Sota The Sota is the shortest among the three main rivers of the basin. From its source to the confluence with the Niger the Sota is about 195km long. The Sota has three important tributaries suitable for Simulium breeding. These are - Irani, Bouli. and Tassine. Among the three main rivers of the basin the Sota has the longest flow period. This period covers weeks 16 to 3 of the following year. The discharge on the Sota can reach a maximum of over 230 cubic metres per second. This was realised in week 43 in 1989; (fig. 5). 4. ENTOMOLOGTCAL ACTTVTTTES (EVALUATTON AND VECTOR CONTROL) 4.1. Enltomolosical surveillance Entomological surveillance network started in the Niger tributaries' basin area tn l976like in all the Phase III East areas. Both vector monitoring and prospection or larval checks were carried out by the following Sub-sectors - Kandi (under the ex Natitingou Sector), Natitingou and Niamey. 4.1.1. Breedins points (fie.6) 4.1.1.1. Mekrou The main S. damnosum s.l. breeding sites, on the Mekrou, are located on the river stretches, codes NM 300 and NM 400. 1.1.1.2. Alibori On the Alibori, the main breeding sites are located on the stretches, codes, NA 200 to NA 400. The Alibori tributaries that are important for S. damnosum s.l. breeding can be found on the river stretches NA 300 and NA 400. 4.1.1.3. Sota The important breeding points on the Sota are located on the stretches .NS 200 and NS 300. On the tributaries of the Sota, the important tributaries are located on the Irani at NS 402. on the Bouli at NS 303 and 302. and on the Tassine at NS 202; (frg.6 and 8). 1.1.2. Catching points. (fig. 7). * In order to make the work easier for the Aerial Operations team, river stretches are coded by taking intct accottnt, the name of the river basin and adding a number.from I00 to 900. For example : NS 200 qnd NS 300 means . Sota river, stretches : 200 ond 300. 6 1.1.2.1. Mekrou The total number of catching points on the Mekrou along the years had been four. These are Kouande (1810), Yeri (0716), Keremou (1906), and Kerou (1917). Except Kerou, which was created in January 1977 , the first three catching points were created in ),976. Yeri (0716) The first catch was made at Yeri in November 1976. This point was under Niamey Sub-sector. Yeri was regularly used as monitoring point until 1991, the year at which the Niamey Sub-sector was closed down. ( r 810) The first catch was made at Kouande in August 1976, and was used regularly until 1981. This point was under the then Natitingou Sub-sector. Keremou (1906) The first catch was made at Keremou in August 1976, and was regularly used until 1993, when the Kandi Sub-sector was closed down. Kerou ( 1917) The first catch was made at Kerou in January 1977.and was used regularly until 1991. Like Keremou. Kerou was under the Kandi Sub-sector. 1.1.2.2. Alibori The total number of points on the Alibori along the years was three. These are Kargui (1904), Alibori ( 1905). and Lougou ( 1 91 9). Kargui (1904) The first catch was made in August l976,but Kargui was used as a monitoring point for only three years. namely, from 7976 to 1979. Alibori on the Alibori had its first catch in August 1976 and was used regularly until 1995 Lousou (1919) The first catch of Lougou was made in August 1985. The reason for the creation of this catching point was the exceptionally high prevalence of "Oncho" at Lougou (Epi village 325), in 1984. 4.1.2.3. Sota and tributaries The Sota and its tributaries had six main catching points along the years. Three of these points are found on the Sota itself, namely, Monkassa (1916), Ferekire (1915), and Gbasse (1901). On the tributaries of the Sota, Irane River has Koutakroukrou (1902), Bouli River has Zougou (1907), and Tassine River has Dunkassa (1908). 7 4.1.2.3.1. Sota Gbasse (.1901) Gbasse is the first catching point of the Kandi Sub-sector. The first catch was made at this point in August 1976. This point had then been a regular catching point until the closure of the Kandi Sub-sector in 1995. Ferekire (1915) Ferekire was created in 1976. The first catch was rnade in August the same year and had been used as a regular catching point until the closure of the Kandi Sub-sector in 1995. Monkassa (1e16) This point was createdinl9ll, and was used for seven years. Monkassa was abandoned in 1984 due to low fly count during monitoring. See graph on ABR on the Sota and tributaries (fig. 12).. 3. 1.2.3.2. Sota tributaries Zougou .1907) Zougou on the Bouli River was created in 1977 . The point was then used regularly until the closure of the Kandi Sub-sector in 1995. Koutakroukrou ( 1902) Koutakroukrou on the Irani River was created rn 1976. The first catch was made in August the same year. It was used regularly until 1987. Dunkassa (1908) Dunkassa on the Tassine River was created rn 19J6, and the first catch was made in August the same year. The point was used regularly until 1989. This point was abandoned due to reduction in the number of catching points carried out that year and also due to its low fly count during rnonitoring. _ 4.1.3. Entomological prcuipections Several entomological helicopter prospections were carried out on the Niger River tributaries in Benin for various reasons. Among these were the following: 1. Investigations into suspected treatment failure 2. Mapping of breeding sites To investigate the problem of re-invasion of these tributaries by flies from Nigeria. Finally for a particular research need at a particular period 3 4 4.2. History on larviciding 8 4.2.1. Aerial larvicidins Aerial larviciding began in the Niger tributaries basin in Benin at the onset of the rainy season rn 1977, barely ayear after pre-control monitoring. Larviciding began on all the three tributaries of the basin. namely, the Mekrou. the Alibori and the Sota, in the same period. The insecticide used then was temephos (Abate'). Temephos was the sole product used in the Niger tributaries' basin in Benin from 1977 to 1987 when B.t. H-14 was introduced into the system for the hrst time in week 46 on the Mekrou and Alibori and week 47 on the Sota. This means that at least temephos was used in the basin continuously for ten years. See tables 1,2 and3). It is important to mention that, the larvicides data. over the years l9l7 to 1980 were not retrievable because of the archival conditions which were not adequate at the very beginning of the Programme. However the Mekrou, the Alibori anfl the Sota have been treated with temephos as usual, e.i. when the rivers were flowing. I l In a given year. larviciding usually beginJ around week 20 and ends on week 50 or 52 on the Mekrou and on the Alibori. On the Sota however the treatment period varied considerably throughout the years. The period depended on the amount of rainfall for the given year. For example in 1982, which was a very good year for the rains, the Sota was treated throughout the year. On the other hand, in 1983 when the sub-region experienced a very serious drought, treatment was suspended for 20 weeks (from week 5 to 25). 4.2.2. Ground larvlqrdlnc Ground larviciding was not used in the Niger tributaries' basin in Benin as the main method of vector control but as support to aerial larviciding in the case of treatment failure due to bad passage of larvicide or when a breeding site is missed after the passage of an aircraft. It was also used in the dry season on certain isolated breeding points to minimise treatment cost of aerial larviciding as in the case of the Sota. From 1990 to 1994 the dry season treatment was through ground larviciding, carried out by the Kandi Sub-sector staff with the help of the village communities. This was to reduce helicopter-flying cost. namely, avoiding the ferry from the Kara aerial base to the Sota to treat some few breeding sites. At very low discharge in the dry season and at the beginning of the rainy season when aerial larviciding was difficult to carry out, ground larviciding was again employed. This was usually between weeks 1 to 20, on the tributaries. The Natitingou, Kandi (both of the ex Parakou Sector) and Niamey Sub-sectors carried out ground larviciding, depending on the location of the points to be treated. 4.2.3. Insecticides used (insecticide rotation) Flom 1977 to 1987 temephos was the only larvicide used on all the tributaries in the Basin. B.t. H-I4 was first used on the Mekrou in week 46 of 1987. This was true also for the Alibori. On the other hand . B.t. }f-14 was used on the Sota for the hrst tirne in week 47 of 1987. I 4.2.3.1. Mekrou On the Mekrou only four out of the seven insecticides used by the Programme were employed tlrroughout the treatment period. These were temephos, B.r. H-14, permethrin, and pyraclofos. Permethrin was used for the first time on the Mekrou in week 36 of 1991, then in week 39 of the same year. These two weeks were the only weeks when permethrin was used on the Mekrou. Pyraclofos w'as introduced for the first time on the Mekrou in week 3l of 1992, it was regularly used when needed till 1993, when aerial larviciding was stopped on the Mekrou. 1.2.3.2. Alibori On the Alibori, like the Mekrou, again only four out of the seven insecticides used by the Programme were employed throughout the treatment period. They were the same insecticides as on the Mekrou. namely, temephos. B.t. H-14, permethrin, and pyraclofos. Permethrin was used on the Alibori G.{A300 to NA500), for only five weeks, namely in weeks 36.37 and 38 in 1993 and weeks 39 and 40 in 1994. Llke the Mekrou pyraclofos was introduced for the first time on the Alibori in week 3 7 of 1992 and was regularly used until the end of the treatment period of the Alibori in 1994. 4.2.3.3. Sota The seven insecticides used by the Programme were employed on the Sota. These were temephos, B.t. H-14, chlorphoxim, phoxim, carbosulfan. pyraclofos. and permethrin. Chlorphoxim was introduced for the first time on the Sota in week 32 in 1989. It was used again in weeks 33 and 34, and then weeks 40 to 46 after which chlorphoxim was never used again on the Sota. Permethrin was f,rrst introduced on the Sota in week 37 in 1990 and was used when needed till tl-re end of the treatment period of the Sota at the end of 1994. Carbosulfan was used for the first time on the Sota in week 30 of 1991 and was also used wlren needed till the end of the treatment period in 1994. Phoxim was firstused in week24 in 1991, then from weeks 25 to 26 on the entire Sota, and then weeks 28 and29 rnthe middle portion of the Sota. Finally in weeks 30 to 35 on upper portion of the Sota, after which phoxim was never again used on the Sota. Pyraclofos was first used on the Sota in week 37 nt 1992, and was from then used as often as it was needed till the end of the treatment period in 1994. From the history of insecticides used in Niger tributaries basin in Benin, insecticide rotation really began in i987 with the introduction of B.t. H-14. Rotation of insecticide was carried out with AbateG', B.t. H-14, phoxim, chlorphoxim, pyraclofos, permethrin. and carbosulfan in the basin as a whole. The reasons for the rotation of insecticides are as fbllows: 1. To prevent the occurrence of resistance, which may occur if only one insecticide is used, as occurred with Abatet in the early stages of the Programme. In order to avoid this, the consecutive use of insecticides belonging to the same chemical compound is discouraged to prevent cross-resistance. 2. The rotation is also carried out forthe cost effectiveness of treatment. Using B.t. }{-14 at very high discharge will require a huge volume of insecticide. This will mean a requirement of a lot of f'erry time for an aircraft and loading. On the other hand an insecticide like permethrin which is highly toxic requires very small volume at very high discharge, thus a small amount can cover u ,o, or rr.]J, stretch to be treated. 3. Rotation of insecticide is carried out according to the toxicity of the insecticide at different disclrarges on non-target organisms. For example B.t. H-14 which has a very low toxicity on non- target organisms is used at low discharges, namely from I cubic metre per second to about 35 cubic metres per second. While permethrin and carbosulfan, which are highly toxic, are only used when the discharge is higher than 70 cubic metres per second and cannot be used for more than six treatment cycles in a given year. Pyraclofos is used at a discharge of 15 cubic metres per second onwards. On the other hand, insecticides like Abate@, phoxim, and chlorphoxim, which have relatively low toxicity. can be used even at low discharge. 1. Finally, rotation is carried out according to the camy of the insecticide. B.t. H-14, for example, which has very short carry, will require a lot of treatment points at higher discharges. This therefore renders it unsuitable for high discharge treatment because of the quantity of product to be used at short distances. It will not therefore be cost effective to use B.t. H-14 at high discharges as pointed out earlier on. However an insecticide like Abate@, which has a very good carry coupled with its low toxicity on non-target organisms can be used at almost any discharge. Pyraclofos is another insecticide, which has a very good carry but because of its toxicity as indicated earlier on, is used fi'orn 15 cubic metres per second upwards. The practical aspect of the rotation of insecticide can be seen on the table of treatment of the rivers of the Niger tributaries basin in the annex of this report; (tables 1,2 and3). -1.3. Entomological results 4.3.1. The vectors involved To determine the vectors involved in the Niger tributaries' basin, adult flies were caught by vector collectors as described by Walsh et al (1978) and are separated into different groups through tlreir wing tuft examination using Kurtak et al (1981) rnethod. These groups were classified as 01, 02. 03. 04, and 05. The 01 groups are the ones with 100% pale individual hairs of the wing tuft. The 02 groups are the ones with the majority of individual hairs of the wing tuft pale, with the presence of some few dark hairs (less than 50Yo of the total numbers of the wing tuft hairs). These two groups are considered to belong to the savannah group of species. narnely, S. damnosum s.s and S. sirbanum The 03 grollps are the ones in which 50o/o are pale hairs and 50o/o are dark hairs. These can be savannah species (S. damnosum s.s) or S. squamosum or can even be S. soubrense. These are however rare in the Niger tributaries' basin in Benin. The 04 groups are those in which the majority of the wing tuft hairs are dark, and the 05 groups are those with 100% dark wing tuft hairs. These two groups are the forest species S. sanctipauli or S. soubrense [although it had been pointed out that some members of adult flies morphologically looking S. soubrense Beffa form have pale wing tuft (Garms 1978 and Meredith er a/ 1 983.). These however had disappeared after the 1983 drought (Cheke et ol 1987)1. From the data available for larval population, the dominant species in the Niger tributaries basin in Benin is S. sirbanum with some few S. damnosum s.s. No other species had been recorded in tlre Niger tributaries' basin in Benin. See tables 4,5 and 6 of cytotaxonomy results in the annex of this report. 11 From the data available for adult population, the ABRs (Annual Biting Rate) showed very few 04-05 wing tuft flies that had been caught in the basin. For example, on the Mekrou at Keremou an ABR of 6 for 04-05 was obtained in 1980 out of a total ABR of 12.022.In 1982 for the same point, an ABR of 12 was obtained out of a total ABR of 4.223. Apart from these two occasions no dark wing tuft flies had been caught on any of the catching points of the Mekrou; (fig. l0). On the Alibori, an ABR of 60 for dark wing tuft flies out of a total of 21.016 was obtained in 1980 at Alibori catching point. Then an ABR of 8 for dark wing tuft flies out of a total of 3,663 was obtained in 1985 at the same catching point. Apart from these two occasions no other year recorded any dark wing tuft flies at this point. At Lougou catching point only 1993 recorded an ABR 4 for dark wing tuft flies out of a total ABR of 20,016; (fig. 1 l). The Sota and tributaries did show different trend apart from what had been obtained on the Mekrou and on the Alibori. On the Sota at Gbasse 1980, 198 l. 7982, 1983, and 1985, gave ABRs for darkwingtuftfliesof 59, l,4.6,and23,outof totalABRs of 54.722;23,323,26,879 24,913;and 17.433 respectively. At Ferekire only in 1980 an ABR of 12 for dark wing tuft flies out of a total ABR of 2,377 was obtained. No ABR for dark wing tuft was recorded at Monkassa. On the Irani at Koutakroukrou 1 980 and 1982 gave ABRs 7 and 4 for dark wing tuft flies out of total ABRs of 6,9 1 I and 1.557 respectively. On the Bouli at Zougou 1980, 1981. 1982, and 1983, gave ABRs for dark wing tuft flies of 88, 6, 13, and 5, out of total ABRs of 26,147 . 8,770;20,071 and 6,649 respectively. Finally Dunkassa on the Tassine out of eight years of monitoring, five years gave ABRs of dark wing tuft flies. The years were 1982, 1983, 1985,7986, and 1987, which gave ABRs for dark wing tuft flies of 9,6, 15. 8, and 8, out of total ABRs of 1,831;231;1,682;533 and 2,063 respectively; (fig. 12 and I 3). From all the three rivers of the basin it can be seen that although some dark wing tuft flies rvere caught, these were insignificant compared with the pale wing tuft flies. This in fact confirms the cytotaxonomy results already mentioned. 4.3.2. The parasite involved To determine the parasites involved in the basin, all the samples of the flies caught in the basin were dissected to first determine the age of the flies. Secondly to look for the presence of Onchocerca parasites in the flies and identify them with the help of dissecting microscope. Thirdly to classify them as either Onchocerca volvulus parasite or non-Onchocerca parasite. The rate of infection is then calculated as described by Walsh et al (1978) to give the Monthly Transmission Potential (MTP) when this is calculated on monthly basis. The sum of all the MTPs for a year gives what is known as the Annual Transmission Potential (ATP) for that particular point. With this method. the parasite can either be described as Onchocerca parasite or non-Onchocerca parasite. Since the creation of the molecular biology laboratory, it had then been possible to classify the Onchocerca parasites into savannah type or the forest type and even to separate Onchocerca volvulus from Onchocerca ochengi. The results from the molecular biology laboratory had shown that the majority of Onchocerca volvulus parasites transmitted in the Niger tributaries' basin had been the Savannah strains. Occasionally some forest strains were also transmitted. 4.3.2.1. Mekrou On the Mekrou out of 18 positive identification of Onchocerca volvulus parasites from 1992 to 1993. only 1 was identified as forest strain. The remaining 17 were identified as 16 savannah strains and I Onchocerca species (strain undetermined); (table 7). 12 4.3.2.2. Alibori From 1992 to 1995 a total of 45 Onchocerca parasites were identified on the Alibori. Out of these 33 were found to be the savannah strain, 5 were found to be forest strain, the remaining 7 were found to be Onchocerca species (strain undetermined); (table 8). 4.3.2.3. Sota A total of 65 Onchocerca parasites were identified on the Sota from 1992 to 1995. Out of these only 1 was found to be forest strain. and one as Onchocerca species (strain unidentified), the rest were all savannah strain; (table 9). 4.3.3. Transmission 4.3.3.1. Pre-control transmission The pre-control ATPs (Annual Transmission Potentials) on all the three rivers of the basin were below 2,500. The highest pre-control ATP was recorded at Alibori catching point on the Alibori (2.313) in 1977. The second highest ATP (2,148) was recorded at Gbasse catching point on the Sota in 1978. The third highest ATP (1,763) was recorded at Zougou catching point on the Bouli River in 1978. On the Mekrou the highest pre-control ATP (1,398) was recorded at Keremou catching point in 1976; (table 9 bis and figures 14,15,16 and l7). 4.3.3.2. Transmission during control period In 1980 barely three years after aerial larviciding began, the ATPs started their downward trends on all the three main rivers of the basin. On the Mekrou. from an initial ATP of 1,398 in 1976 at Keremou the ATP came down to 200 in 1980 On the Alibori at Alibori the ATP dropped fuom 2,313 in 1977 to 1.905 in 1980. This downward trend continued until the end of aerial larviciding operations in1994. At the end of 1994 the ATP recorded at Alibori was 107. On the Sota at Gbasse. ATP of 2,1 48 in 1978 dropped to 1,093 in 1980. Unlike the Alibori and the Mekrou did not follow steady downward trend. The drop in ATP observed on the Sota was very erratic. For example, from ATP of 1,093 in 1980, a steady drop was observed to 1982, namely, 1981 lrad an ATP of 829, then in 1982 it went down to 407, but in 1983 it jumped up to 1,004. After 1983, the drop in ATP was again steady until 1987 when a jurnp was observed. This pattern was observed throughout the control period. Even the last but one year of cessation of larviciding (1994), the ATP jumped from 147 in 1993 to 1,1 1 1. This had been the case because of infected flies contaminating the Sota valley from Nigeria. If one observed the cumulated monthly transmission potential majority of infection occurred in June and July each year, namely, at the beginning of the rainy season when the valley is heavily contaminated. Which meant that the flies came into the Sota valley already infected. See histogram of monthly-cumulated MTP from data compiled from 19ll to 1994;' (fig. 18). 5. SURVEILLANCE OF AQUATIC FAUNA Larvicides used by OCP are degradable and do not accumulate in the food chain. The quantities used for larviciding are not harmful for men or mammels. This is the primary requirement for OCP to select a larvicide. 13 The insecticides that meet these requirements are then screened according to the standards of the OCP Programme and its Ecological Group. This independent Ecological Group which is composed of International scientific Experts studies the results and guides OCP activities in the surveillance and protection of aquatic fauna. The surveillance and protection of aquatic fauna is the task of National Teams of hydrobiologists (invertebrates and fish); see figure 19 for the location of the sites of aquatic surveillance. No aquatic monitoring site was established on these three Niger tributaries basin in Benin. Results of the hydrobiological monitoring on rivers treated with the same larvicides showed no long-term impact on non target fauna. 6. EPIDEMIOLOGICAL EVALUATIONS 6.1. Epidemiolosical results before Vector control. 6.1.1. Mekrou To illustrate the Epidemiological (Epi) situation on the Mekrou, two Epi villages are chosen. These are Gbeniki (code 328) and Yakrigourou (code 319). The pre-vector control results for Epi surveys were Onchocerciasis prevalence of 50.1%o and prevalence blind of 0.67% for Gbeniki. and for Yakrigourou prevalence of 71.9Yo and prevalence blind of lYo. These two villages were chosen because of the continuity of surveys carried out in these villages; (fig. 2l and22). 6.1.2. Alibori The Epi villages on the Alibori chosen for this report were Lougou (code 325) and Alibori (code 329). At Lougou the pre-vector control results for Epi surveys were Onchocerciasis prevalence of 6lYo and prevalence blind of l.5o/o and at Alibori a prevalence of 68.7%o with prevalence blind of l.9Yo, (frg.23 and 24). 6.1.3. Sota On the Sota Wanrarou (code 335) and Zondji-Gbasse (code 330) were chosen. At Wanrarou tlre pre-vector control results for Epi surveys were Onchocerciasis prevalence of 35.6oh wll'h prevalence blind of 0%, and at Zondy-Gbasse an Onchocerciasis prevalence of 68.8% with prevalence blind of 2.4%o; (frg.25 and26). For the locations of these villages mentioned see map of Epi villages in the Niger tributaries' basin in Benin in the annex of this report; (fig. 20). 6.2. Epidemioloeical results durins Vector control. During the vector control period the fall in the onchocerciasis prevalence followed a typical pattern in an observed prevalence trend in the course vector control on all the rivers of the basin. The pattern was however changed on the Alibori at both Lougou and Alibori villages in 1992, namely, there was a sharper fall in prevalence in 1992 (15 years of vector control). Sulveys conducted two years later in these two villages showed again the normal trend; (fig. 23 and 24). The reason was that tlre Alibori villages were treated with ivermectin in 1992. According to our data there were no ivermectin treatments on the Alibori in 1993 and 1994. Then, the treatment resumed in 1995; (table l0). 14 6.3. Latest Ep sical results Except on the Alibori where the latest epidemiological results showed prevalence of more rhan l\Yo at both Lougou and Alibori the rest of the villages in the basin gave prevalence of less than 10%. Tlre graphs on epidemiological situation on the Alibori at Alibori gave a prevalence of 13.loh after 17 years of vector control, and at Lougou the prevalence was even higher. namely a prevalence of 20 .4oh after ll years of vector control, (fig. 2l to 24) . 7. IVERMECTINDISTRIBUTION. 7.1. Mekrou The Mekrou valley had been treated with ivermectin in 1989 , 1992 and 1994; (table I 3 ) 7.2. Alibori According to the large-scale ivermectin distribution data, ivermectin distribution began in the Alibori valley in 1992 (table 10). It is important to note that the Alibori valley was treated three times iri 1995 in the Zone 9 area. The distribution was carried out in January as already pointed out. The second in June to July and the third in December. The reason for this action was due to the relatively high prevalence recorded in this valley in 1994 (see graphs on Epi situation on the Alibori, figures 23 and24). 7.3. Sota In the Sota valley large-scale ivermectin distribution began in March 1989 in 16 villages where 6.063 people were treated. From this date to 1995 large-scale ivermectin distributions were carried out in the Sota valley regularly once each year with increasing number of villages being covered. From 16 villages covered in 1989, by 1994. 137 villages were covered treating a total of 28,558 people compared to 6.063 people treated in 1989. In 1995 when the Alibori valley was added to the Sota valley,244 vrllases were covered treating a total of 49,836 people. It should be noted here that, from 1989 to the end of 1996,the national teams headed by the national Co-ordinator carried out large-scale ivermectin distributions, involving the local health units in the various districts. In January 1997 the village communities were trained to carry out large-scale ivermectin distribution themselves. and this had therefore been the practice since then. For the details of ivermectin distribution in the basin see table 13 in the annex of this report. SOCIOLOGICAL INVESTIGATIONS. At the time of writing. no sociological investigation had been carried out in the basin to date 9. POPULATIONS SENSITIZATION AND MOBILIZ ATTON ACTIVITIES It is important to recall that since 1974, OCP Programme management have constantly expressed the need to get various community social elements involved in sensitization and mobilization activities whenever this was feasable. 8. As from 1975 aninformation campaign through the media and health education ,..ut"", .Ju? launched to sensitize people about the dangers relating to onchocerciasis. Advertisement on posters and in the media was used. The communities were rapidly able to understand the relationship between the black flies and blindness as well as the objectives of the programme. They understood the weekly intervention of airplanes and helicopters that carried out aerial larviciding. The efforts to provide infbrmation did not target populations at risk only. They also targeted administrative and health authorities to ensure their full adherence. They also targeted donors countries which were concerned with the monitoring of an action they were supporting. Population sensitization and mobilization activities are ensured by VCU teams during entomological prospections, and by national teams before epidemiological evaluations and ivermectin distribution. All the social segments as well as the political and administrative authorities in the areas visited by the teams were targeted by the sensitization (teachers, traditional healers, health agents and religious leaders, etc.). Talks were organized and leaflets on OCP activities were distributed in the villages; and films were shown anytime that was possible. The following themes were discussed during the talks * Onchocerciasis transmission; relation between the river, the bites of the black flies and the disease. *The clinical signs of the disease: itching, acute skin lesions (onchocerciasis dermatitis), nodules, chronic cutaneous symptoms (depigmentation), dimsight (progressive visual impainnent. blindness) * The socio-economic consequences; disabilities (blindness), abandonment of first line villages (closest to the river) and most fertile valleys. which is an obstacle to socio- economic development. + The control of the disease. vector control, ground larviciding. chemiotherapy (treatment with ivermectin). Regarding vector control, the involvement of the populations is requested to look after l<erosene and insecticde stocks to prevent theft. Concerning ivermectin treatment, a particular emphasis is laid on the doses to administer depending on patients' size, contra-indications, periodicity, drug intake regularity, side effects and appropriate behavior. The progressive intensification of sensitization resulted in the gradual increase in the coverage of ivermectin distribution. It also resulted in the easier acceptance of skin snip during epidemiological surveys. As far as vector control is concerned, the sensitization of populations led to a significant leduction of cases of theft of kerosene and insecticides in the depots in the field. 16 10. DISCUSSIONS. 10.1. During the ten years of continuous use of temephos in the Niger tributaries' basin in Benin, no resistance to this product was recorded. It would be interesting to note that temephos was the only product (larvicide) used in the basin from 1977, without interruption, to 1987. Temephos was used on all the three main tributaries (the Mekrou, the Alibori and the Sota) of the basin. Susceptibility to ternephos was normal on all the three tributaries until 1989 when the susceptibility became intermediate on the Sota, but returned to normal in 1990. The intermediate situation was again obtained on the Sota in 1991. Aparl from these two cases no resistance to temephos had been detected elsewhere in the basin. This may be due to the fact that the majority of the Simulium population in the basin consists of S. sirbanum. Formore details of susceptibility situation of temephos inthe basin see graph of susceptibility tests on temephos in the eastern Zone from 1980 to 1998 in the annex of this report; (fig. 9). 10.2. From the history of the creation of the catching points it can be seen that the first catching was carried out at Lougou in i985. The reason for the creation of this point in that year was due to the prevalence of Onchocerciasis at this epidemiological village at the time. The prevalence was found to be on the high side after 8 years of vector control. On the other hand the ATP at Alibori catching point (the nearest entomological monitoring point to Lougou Epi village) was good, taking into account the number of years of vector control. It became therefore necessary to find an answer to this high prevalence at Lougou hence the creation of Lougou catching point in 1985 to monitor this situation. 10.3. The Niger tributaries'basin has a very unique feature, namely, in this basin apart from S. darnnosum s.s and S. sirbanum, no other Simulium species has ever been found, and on the Mekrou the only cytotaxonomy data available gave only S. sirbanum. Can this explain the reason why resistance to temephos had not been detected in this basin on a higher scale? It is known from the history of resistance to temephos that this was first detected with the forest species of S. damnosum s.l (S. sanctipauli and S. soubrense) in the Ivory Coast on the Lower Bandama in May1980, only 16 months of the beginning of vector control with temephos. Resistance to temephos later spread to the savannah species in the area (Guillet P. et al 1980). The absence of forest species in the Niger tributaries' basin in Benin might have therefore favoured the prolong use of temephos in the basin without developing resistance. 10.4. Notwithstanding the fact that vector control and large-scale ivermectin distribution had been intensive in the Sota valley, the ATPs on the Sota and tributary Bouli were on the higher side at Gbasse and at Zougou at the end of vector control operations. This showed that transmission in this valley is greatly influenced by contaminating flies from neighbouring rivers from Nigeria. This is clearly shown by the graph of monthly transmission compiled from data ftom 1977 to 1994 in the annex of this report. From this graph it is shown that infections occur mainly at beginning months of the rainy season (June, July and August), namely, months of contamination of the Sota valley; (fig. 1 8). I1. CONCLUSION In general. from the entomological results by way of transmission (ATPs) and the Epidemiological results by way of trend in prevalence, the vector control operations had been successful in the Niger tributaries' basin in Benin. On the other hand the trend of prevalence in the Alibori valley showed an upward direction after 17 years of vector control. Then on the Sota and tributaries at Gbasse and at Zougou the ATPs were on the higher side, namely. over 600 at Gbasse and nearly 500 at Zougou on the Bouli. This situation had already been discussed in this report. 17 ACKNOWLEDGEMENTS My sincere thanks go to the Programme Director of OCP and the acting Chief of Vector Control Unit (VCU) for giving me the singular honour by inviting me to come to Ouagadougou to write this reporl. The writing of this report should not have been possible without the help of all the VCU staff in both Ouagadougou and in the field. This is to say a big thank you to them all. My special thanks go to Mr. AKE Flavien for the vital tips provided in the use of the computer in the writing of this report, in the making of the various graphs and the maps of this report. Many thanks to Mr S. N'GADJAGA for all the computer installations which made it easier for me to write this report. I will also like to express my sincere gratitude to the PET Unit for the epidemiological infbrmation provided as well as the data on the large-scale ivermectin distribution in the Niger Tributaries basin in Benin. 18 REFERENCES. Cheke R. A.. Garms R., Ouedraogo J., Some A.. Sowah S., (1978). The Beffa form of Simulium soubrense of S. damnosum complex in Togo and Benin. Medical and Veterinary Entomology (1987 ) l. 29-35 Cheke R. A., Sowah S.. Avissey H. S. K., Fiasorgbor G. K., and Garms R. (1991) Seasonal variation in Onchocerciasis transmission by S. squamosum at perennial breeding sites in Togo. Transactions of the Royal Society of Tropical Medicine and Hygiene (1991) 85. Cheke R. A., Avissey H. S. K., Sowah S., Walsh J. F.. and Garms R. The vectorial Efficiency of Sirnulium yahense populations in South-Eastern Ghana. (In press). Cooter R. J. (1983). Studies on the flight of the black flies (Diptera: Simuliidae). II. Flight performance of thlee cytospecies in the complex of Simulium damnosum. Theobald Bulletin of Entomological Research. 7 3 . 27 5 -288. Garms R. (1978). Use of morphological characters in the study of Simulium damnosum s.l population in West Africa. Tropenmedizin and Parasitology (1978) 29.483-491 Garms R., Cheke R. A.. Vajime C. G., and Sowah S. (1982). The occurrence and movement of different members of Simulium damnosum complex in Togo and Benin. Z. angew Zool (1982). 69. 219-236. Garms R., Cheke R. A. (1985). Infection with Onchocerca volvulus in different members of the Simulium damnosum complex in Togo and Benin. Z. angew Zool (1985) 72. 419-495. Guillet P., Esaffre H., Ouedraogo M., Quillevere D.,(1980). Mise en evidence d'une resistance au temephos dans le complexe Simulium damnosum (5. sanctipauli et S. soubrense) en Cote d'Voire (zone du programme de lutte contre l'onchocercose dans la region du Bassin de la Volta). Kurtak D., Raybould J.. Vajime C. (1981). Wing tuft colours in the progeny of a single individuals of Sintulium scluamosum (Enderlein). Trans. Royal Soc. of Trop. Med. and Hyg.. Vol. 75 No. 1, 1981. Colrespondence. Ktrrtak D. (1990). Maintenance of effective control of Sintulium damnos'um in the face of insecticide resistance. Acta Leidensia 59:95-1 1 2. Meredith S. E. O., Cheke R. A., and Garms R. (1983). Variation and distribution of forms of Simulium soubrense and Simulium sanctipauli in West Africa. Annals of Tropical Medicine and Parasitology (1983) 77. 627-640 Kurtak D.. Meyer R.. Ocran M.. Ouedraogo M., Renaud P.. Sawadogo R., Tele B., (1987). Management of insecticide resistance in control of Simulium damnosum complex by the Onchocerciasis Control Programme: West Africa: potential use of negative correlation between organophosphate resistance and pyrethroid susceptibility. Med. Vet. Entomol. l:137-146. Remme J., Desole G.. Dadzie K.Y., Alley E. S., Baker R. H., Habbema J. D., Plaisier A. P., and van Oortimarssen G. J. (1990). Large-scale ivermectin distribution and its epidemiological consequences. (Review) Acta Leidensia. 5991-2): 177 -91. 1 990. 19 Sowah S. A.. Kassambaro M., Avissey H. K. S., Amadou A., and Gbaguidi P. (1992). Seasonal Variation of S. soubrense Beffa form population in the Oueme valley and its vectorial efficiency in 1991 and 1992. (Unpublished). Vajime C., and Quillevere (1978). The distribution of the Simulium damnosum complex in West Africa with particular reference to the Onchocerciasis Control Programme area. Tropenmedizin and Parasitology ( I 978) 29. 47 3-482). Walsh J. F.. Davies J. B., Le Berre R., (1978). Standardization of criteria for assessing the effect of Simuliurz control in onchocerciasis control programme. Trans. Royal Soc. of Trop. Med. and Hyg.. Correspondence. ANNEXES El H. 0a Fl o rt,L r-: \ ( l* i= .Er (@\-\ J- r Eln S I '{. lr $- oz C) -OO!om ma,cA-.m !J=x >(Jp8f ;8tr z>u, 4aO vtn7 0a e;qi ds x8i m Pt1 = =0Ei6b v=v mo>{ '- 6moJ i__ a 7 z c -m o mZg +r o!l(,(,>odifBiI ax I - o dagat 33 "ooa-.r oos 6 !1 6 ioo o6 o ro oO _| lt -ilil EP93E,e E6d &*il 9. 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I 1 -l , II d ,lIt i T; ,,,,,,,", // AQUATTC MONTTORTNG STTES (AS OF 1994) STATIONS DE SURVEILLANCE AQUATIQUE (SITUATION EN 1994) , I I \\ l I I t( \ t COTONOU o o t LOMEo,. \ t ACCRA ,er-' -- -Sassandra AEIDJAI'I * Fish monitonng sites Stations de sunrerllance de la faune rcht),ologrque Original Programme area Aire initiale du Programme o tr I ln\Ertebrates monrtonng srtes Statrons de surveillance de la faune rn\,ert6br6e LaModing odensions Zones d'exteflsion des traitements larvicdes Srtes no longer vlsrted (Frsh) Stations qur ne sont plus visrt6es (Faune rchtlologrque) Area treated with ivermect n alone Zones trait6es a ll\rermectine seul Srtes no longer usited (ln\ertebrate) Statrons qur ne sont plus vist6es (Faune invert6br6e) I t. - 0 ! 1 1 0 FiguTe 2O EPI VILLAGES IN THE NIGER TRIBUTARIES, BASIN IN BENIN 29 LEGEND O EPI villages BRIGAMBOU TELANTEGOUoo a KOMBONGOU a o o G o c/) o ZONDJLGBASSE O YAKRIGOUROU O KOUROUGBELE a a oro"*o, ROU o a ALAFlqROU O Table 10 WHO/OCP/PET/BIS 30 Onchoceraasis Control LONGITUDI}{IAI DATA BY COI'NTRY BASIN: MEKROU I-ARVICIDING : Started 1 ma1-S 1977 Ended d6cembre 1993 COUNTRY CATCHING POINT CODE and NAME OF VILLAGE DATE COHORT SEMI4OHORT tNct. EXA. PREV, CiilFL EXA. PREV, CMFL BENIN INDETERMINE 4006IKEREMOU/MEKROU 0/,l2@1 KEROU s6TolBONNr 1 1/1 996 5343IKILIBO-BANJAN 01t19,.92 03t20Fp 144 U 0 saaaJrogece 01t1992 5024IYAKABISSI 09/198S 01t1s92 3IgIYAKRrGOUROU 01t197A 7 45.7 26.il 168 oro 23,99 03/1982 7 100 42,1 92 94,6 33,09 03/1985 7 85.7 15.44 95 85.3 17.92 0 01/1989 7 42,9 0,72 88 0,6 0 01t1992 7 14.3 0,06 61 11,5 0,1'l 1,07527 03/2(m 7 0 0 27 0 0 0 KOUANDE 310 MEKROU.GOUROU o5l19T7 02/1 I/2002 Page 1 of I Table 11 WHO/OCP/PET/BIS LONGITUDI}iIAI DATA BY COUNTRY BASIN: ALIBORI/NIGER LARVICIDING : Started : mars 1977 Ended decembre 1994 Onchoceruasrs Conlrol 31 COUNTRY CATCHING POINT CODE and NAME OF VILI-AGE DATE COHORT SEMI.COHORT tNct. EXA. PREV CMFL EXA. PREV CMFL BENIN ALIBORI 32glAUBORt o3t1978 a 1m *.21 56 91.1 22.72 o3t1982 a 100 62,49 25 100 6,37 o3/1985 3 66.7 '10.5 19 94.7 28.55 6,66667 01/1989 3 66,7 3,58 16 87,5 10,81 5,217U o3/1990 3 66.7 3.73 17 70,6 5.34 0 01l1w2 3 0 0 I 11 .1 0.13 0 01t1994 ? U I 37,5 o,n 0 I(ARGUI ss+slsexnrE o4t20o1 LOUGOU se46lorRore o211992 325 LOUGOU o211978 23 95.7 24.58 18 90.5 19,88 01t1982 t5 87 25.72 95 91.5 29.98 11t1984 23 91,3 35,05 98 92,9 xt,25 7,70076 01/1989 23 87 12.O2 86 88,4 12.?5 3.1 6975 02i19f]2 ZJ 26.1 o.47 73 % 0.3s) 0.4533 01/1994 aa 39,1 1.13 69 33,3 o.73 1.13417 03t2wo 23 4.3 0.03 38 't5.8 0.13 0.4fix 02/1 1/2002 Page I of 1 Table 12 WHO/OCP/PET/BIS LONGITT'DINAI DATA BY COI'NTRY BASIN : SOTA/NIGER LARVICIDING : Started : mars 1977 Ended d6cembre 1986 Onchocercnsrs Control 32 COUNTRY CATCHING POINT GODE and NAME OF VILLAGE DATE COHORT SEMI.COHORT tNcl. EXA. PREV. CMFL EXA. PREV CMFL BENIN FEREKIRE 327 KOUBERY o211978 21 95.2 27.28 '165 95.2 24.26 INDETERMINE 4001 MASSANGARI 05/2!ol zl00o ZANROUA 05/2001 PA 5398 AMBERI-GOUMBI 01n993 ZOUGOU 547 GBARANA 0't/1993 549 MONROU 0s/1988 79 42.3 9.27 208 77.4 9.m 031S0 79 49.4 1,99 127 51,2 '1,89 01/1995 79 16.5 0.3 103 12.6 o.2 0.48681 02/I 1/2002 Page I of I Figure 21 WHO/OCP/PET/BIS VILLAGE: GBENIKI Nearest Catching Point KEREMOU Region BORGOU Basin KEREMOU/MEKROU/NIGER IN POPUL,ATION Onchocerciasis C ontrol (Code 328 ) HealthDistrict BANIKOARA Country BENIN LARVICIDING mars 1977 TO d6cembre 1994 IN COHORT IN SEMI-COHORT EPIDEMIOLOGICAI COD4BINED DATA BY VILI,AGE 33 DATE EXA PREV CMFL lncid. 't97803 14 81,8 10,35 198203 41 75,6 5,82 198503 n 51.7 2,ffi 0 198901 56 17,9 0,58 n 199401 28 10,7 o,24 1,17647 Epid6miological Trend 90 80 70 60 50 40 30 20 10 0 '-'o. 1975 1980 1985 1990 1995 Year +-FREV CIVFL - -o- -PFEV e.oh C[vFLCoh - -x- -lt{C DATE lrYPr CENS EXA POS. PREV CMFL BLIN 197803is 400 345 155 50,1 10,38 0,67 198203 S 391 127 44 rm,8 4,93 0,43 19&503 S 381 80 21 24,1 3,18 0,56 19g9or ls 391 155 12,1 0,66 0,39 19s4o1ls 316 124 6 5,7 o,'t2 0 DATE EXA PREV CMFL lncid. 197803 14 92.9 12,8 198203 14 92,9 9,8 198503 14 50 2,14 0 198901 14 14,3 o,u 0 199401 14 7,1 o,17 1,17647 02/I 1/2002 Figure 22 WHO/OCP/PET/BIS Onchocerciasis Control EPIDEMIOLOGICAI COMBINED DATA BY VILI,AGE 34 IN POPULATION 100 90 80 70 60 50 40 30 20 10 0 YAKRIGOUROU KEROU Epid6miologica! Trend a o. (Code 319 ) Health District KEROU Country BENIN LARVICIDING mars 1977 IN COHORT TO d6cembre 1993 IN SEMI.COHORT -.-O. 1975 1980 198s 't990 199s 2000 2005 Year -..+PREV CIVFL - -o- -PREVCoh CIvFLCoh - -x. -tt\,tc onre lrver CENS EXA POS. PREV CMFL BLIN rszaor ls l 447 399 273 71,9 25,73 1 19B2o3ls 459 n7 157 61,3 28,09 1,94 198so3is 470 243 1m 45,7 15,21 2,O7 rsasor ls 514 321 40 9,2 0,55 1,15 190201 S 552 195 15 4,9 o,14 1,O2 2fino3 s 7n fi7 2 0,6 0,01 0,36 DATE EXA PREV CMFL lncid. 197ffi1 7 85.7 %,62 198203 7 1m 42,1 198503 7 85,7 15,U 0 19&901 7 42,9 o,72 U 19gn1 7 't4,3 0,06 1.07527 200003 7 0 0 0 DATE EXA PREV CMFL lncld. 197801 168 92,9 23,99 198203 92 94,6 33,09 198503 G 85,3 17,92 U 198901 88 25 0,6 n 'twn1 61 11,5 0,11 1,07527 200003 27 0 0 U 02/t l/2002 VILLAGE Nearest Catching Point Region ATACORA Basin MEKROU I I Figure 23 WHO/OCP/PET/BIS Onchocerciasis Control EPIDEMIOLOGICAT COMBINED DATA BY VILI,AGE 35 VILLAGE : LOUGOU Nearest Catching Point LOUGOU Region BORGOU Basin ALIBORI/NIGER (Code 325 ) HealthDistrict GOGOUNOU Country BENIN LARVICIDING mars 1977 TO d6cembre 1994 IN POPUL.ATION IN COHORT Epid6miological Trend IN SEMI-COHORT DATE EXA PREV CMFL lncld. 197802 1€ 90,5 19,88 198201 95 91,6 29,98 19841't 98 92,9 %,25 7,7@76 198901 86 88,4 12,35 3,15975 19920.2 73 m 0,39 0,46333 1SS401 69 33,3 o,73 1,13/17 200003 38 15,8 0,13 0,4m4 100 90 80 70 60 50 40 30 20 10 0 1C 1 975 1 980 '1985 1990 Year 1 995 2000 2005 +-PFIEV CIVFL - -o- - FFEV Coh Clt/tt Coh - -x- - ltllC DATE I rrE CENS Ev6 POS. PREV CMFL BLIN 1978o.2 D 351 302 178 61 n 1,52 198201 D 358 266 156 57,2 26,6 o,74 1%411 D 4n 330 178 55,3 18,01 0,9 198901 D 484 353 149 41,3 6,17 19gn2 S 521 fi2 u 9,7 o,24 199401 S 579 44 56 13,1 0,48 z)cm3 S 592 287 7 2.7 0,M OATE EXA PREV CMFL lncid. 1978o.2 7i s5,7 24,8 19820'l n 87 25,72 19841 1 n 91,3 35,05 7,7W76 198901 7i 87 12,O2 3,16975 19€2!2 n %,1 o,47 0,46333 199m1 zi 39,1 1,13 "t,1u17 20oom zi 4,3 0,03 0,4004 02/t 1/2002 I I I Figure 24 WHO/OCP/PET/BIS Onchocerciasis Control EPIDEMIOLOGICAI COMBINED DATA BY VILI,AGE 36 DATE EXA PREV CMFL lncld. 197803 56 91,1 72,72 198203 25 1m $,37 198503 19 94,7 28,55 6,66667 198901 16 87.5 10,81 5,217U 199003 17 70,6 5,U 0 199201 I 11,1 0,13 0 19940'l 37,5 o,a 0 VILLAGE: ALIBORI Nearest Catching Point ALIBORI Region BORGOU Basin ALIBORI/NIGER IN POPUIATION (Code 329 ) Health District KANDI Country BENIN LARVICIDING mars1977 TO d6cembre 1994 IN COHORT IN SEMI.COHORT 120 100 80 60 40 20 Fpid6miological Trend "oo' o q I 1975 1980 't985 1990 1995 Year +PFH/"*-"-.,s-*CIvFL - -o- -PFEVCoh.' *':)- -C[lfLCoh - -x- -f!C DATE I YFE CENS EXA POS. PREV CMFL BLIN 197803 S 1N 1n 81 68,7 24,59 1,91 198203 S 97 66 48 64,6 37,7 1,55 198503 S 102 61 38 66,8 24,72 2,81 198901 S 107 70 32 45,9 6,93 0 199003 S 108 72 31 40,8 4,76 199201 S 102 N 1 4,3 0,05 199401 S 1$ 73 15 n,4 0,98 DATE EXA PREV CMFL lncid. 197803 3 '100 54,21 198203 3 100 d2,49 198503 3 ffi,7 10,5 6,66667 198901 3 66,7 3,58 5,21734 199003 3 ffi,7 3,73 0 19g2o1 J 0 0 0 '19S401 3 0 0 0 02/1 1/2002 I 0 Figure 25 IVHO/OCP/PET/BIS Onchocerciasis Control EPIDEMIOLOGICAI COMBINED DATA BY VILI,AGE VILLAGE : WANRAROU ( Code 335 ) Nearest Catching Point GAMIA Health District BEMBEREKE Region BORGOU Country BENIN Basin BOULUSOTA/NIGER LARVICIDING mars1977 TO d6cembre1994 IN POPUL/ITION IN COHORT IN SEMI-COHORT 37 DATE lrYPr CENS EXA POS. PREV CMFL BLIN 1978031s T5 1U 61 35,6 6,16 0 1982031S 216 150 39 26,8 3,2. 0 198503rS n1 132 39 24 2,45 0 rgagor ls 247 162 13 7,3 0,51 U 199201 S n1 1n 6 4,5 0,13 0 2n103 s 42. %'l U 0 0 0 DATE EXA PREV CMFL lncid. 197803 8 75 9,28 198203 8 62,5 4,31 198503 8 75 1,68 1,85185 19&n1 8 0 0 0 199201 8 0 0 U 200103 I 0 0 0 DATE EXA PREV CMFL lncid. 197803 78 65,4 5,93 198203 51 66,7 5,6 198503 42 u,3 3,93 1,85185 198901 39 '15,4 0,44 0 1gg201 23 8,7 0,1 0 200103 21 0 0 0 Epid6miological Trend 80 70 60 50 40 30 20 10 0 9---O-- q i O. 1 975 1 980 1 985 1990 Year 1 995 2000 2005 .+FRB/ CTUFL - -o- - PFEV Coh CI;FL Coh - -x- - l],lc 02/t I/2002 I I I Figure 26 WHO/OCP/PET/BIS Onchocerciasis Control EPIDEMIOLOGICAI COMBINED DATA BY VILI,AGE VILLAGE : ZONDJI-GBASSE ( Code 330 ) Nearest Catching Point GBASSE Health District SEGBANA Region BORGOU Country BENIN Basin TASSINE/SOTA/NIGER LARVICIDING mars 1977 TO d6cembre 1994 IN POPUI,ATION IN COHORT IN SEMI-COHORT 38 DATE CENS EXA POS. PREV CMFL BLINrE 197803 e n7 2g '168 68,8 24,7 2,44 198203 S 306 188 132 68,6 31,27 1,08 198503 S 335 28 18 58,6 21,ffi o,77 '198901 S 373 n3 86 43,2 4,76 o,2 1SSOO3 S u7 b5 5e 25,2 1,12 0 199112 S 450 371 o2 17,4 o,27 199501 S 535 428 n 6,4 0,11 OATE EXA PREV CMFL lncid. 1 97803 17 94,1 30,63 198203 17 94,1 50,54 198503 17 94,1 42,19 8,771g/3 198901 17 w,2 9,37 1,86333 199(n3 17 41,2 1, 19 7,7924a 159112 17 17,6 0,07 n 199501 17 17,6 0,18 o,44427 DATE EXA PREV CMFL lncid. 197803 124 91,4 24,fi 198203 75 93,3 fi,u 198503 75 g),7 27,57 8,77193 198901 52 a2,7 6,7 1.86333 '19SOO3 57 49,'l 1,51 7,7924€ 1#112 62 21 o,2 0 19e501 z16 19,6 o,2 o.44427 Epid6miological Trend 100 90 80 70 60 50 40 30 20 10 0 I I I I t 1975 1 980 1 985 1 990 I 995 2000 Year -+- PRIB/ CilIFL - -o- - FREV Coh CilIFL Coh - -x- - lt{C 02/1 1/2002 Table 13 39 ONCHOCERCIASIS CONTROL PROGRAMME RESULTS OF LARGE SCALE IVERMECTIN TREATMENT Year Basin Villaqes Census Treated otto 1989 MEKROU 1 3't2 223 71,47 1989 SOTA/NIGER 16 9767 6 063 62,08 1989 SOTA/NIGER 16 9767 6063 62.1 1990 SOTA/NIGER 19 11 527 6201 53,80 1990 SOTA/NIGER 17 1083'l 5796 53,5 1991 SOTA/NIGER 18 11 2U 6 453 57,19 1991 / 1992 SOTA/NIGER 74 30307 20508 67,7 1991 SOTA/NIGER 19 11448 6/,23 56,1 1992 ALIBORI/NIGER 4 1 292 816 63,16 1992 MEKROU 2 517 290 56,09 1993 SOTA/NIGER 102 3ffi2 20099 56,4 1994 MEKROU 1 291 125 42,% 1994 SOTA/NIGER 137 3S75 28558 71.9 '1995 ALIBORI/NIGER 244 68214 49836 73 1995 ALIBORI/NIGER zil 68990 48198 69,9 1995 ALIBORI/NIGER 133 27398 20754 75,7 1996 ALIBORI/NIGER 117 27587 22270 80,72 1996 SOTA/NIGER 142 38,4;07 28471 74,12 1996 SOTA/NIGER 1U 39695 30726 77,4 Table 1-4 40 ABREVIATIONS D6nomination frangaise Siglefranqais Sigle anglais D6nomination anglaise Acide d6soxyribonucleique ADN DNA Deoxyribonucleic Acid Bureau Regional (de I'OMS) pour l'Afiique AFRO AFRO WHO Regional Office for Africa Unitd de Biostatistique et d'lnformatique BIS Biostatistic and Information System Unit Banque mondiale BIRD IBRD World Bank Cornite des Agences parrainantes CAP CSA Committee of Sponsoring Agencies Comitd conjoint de Coordination CCC JCC Joint Coordinating Committee Comit6 consultatif d'Experts CCE EAC Expert Advisory Committee Comit6 conjoint du Programme CCP JPC Joint Programme Committee Charge microfilarienne communautaire CMFC CMFL Community microfi larial Load Organisation des Nations Unies pour I'Agriculture et l'Alinrentation FAO Food and Agricultural Organization Diethycarbamazine DEC DEC Diethycarbamazine Unite d'Evaluation dpiddmiolo gique EPI EPI Epidemiological Evaluation Unit Institut Pierre Richet IPR Institut d'ophtalmologie tropicale de I'Afrique IOTA Microfilaires par biopsie cutande Mf/b Mf/s Microfilaria per skin snip Merck Sharp et Dohme MSD MSD Merck Sharp and Dohme Programme de Lutte contre l'Onchocercose en Afrique de I'Ouest OCP Onchocerciasis Control Programme in West Africa Organisation mondiale de la Sante OMS WHO World Health Organization Institut frangais de Recherche scientifique pour le ddveloppement en Coop6ration ORSTOM Potentiel anluel de Transmission PAT ATP Annual Transmission Potential Amplification g6n6tique par la polymerase PCR Polymerase Chain Reaction Potentiel hebdomadaire de Transmission PHT WTP Weekly Transmission Potential Potentiel mensuel de Transmission PMT MTP Monthly Transmission Potential Programme des Nations Unies pour le D6veloppement PNUD UNDP United Nations Development Programme Taux annuel de piqtres TAP ABR Annual Biting Rate Programme PNUD/Banque rnondiale/OMS pour la Recherche et la Formation concernant les Maladies tropicales TDR TDR TINDP/World Bank/WHO special Programme for Research and Training in tropical Diseases Taux mensuel de piq0res TMP MBR Monthly Biting Rate Agence des Etats Unis pour le Developpement international USAID United States Agency for international Development Unitd de Lutte antivectorielle VCU Vector Control Unit Unitd de Planification. Evaluation et Transfert PET PET Planif,rcation, Evaluation and Transfert Unit