Study of an onchocerciasis control programme in Nigeria

O',,-),o - N WORLD HEALTH ORGANIZATION oRGANISATToN MoNDIALE DE LA saNrE - arrangements have also been finallzed for consultancy services by an entomologist, epidemiologist and an econooist; vBcf78.6 I STUDY OF AN ONCHOCERCIASIS CONIR,OL PROGRA},IME IN NIGERIA 1. INTRODUCTION Since the start of OCP operations i.n seven countries of l.Iest Africa, the Federal Republic of Nigeria has made a request to also join this prograrrne. At the fourth session of the Joint Coordinating Conrnittee (Kur^zait, December 1977) it was stated (page 13 t 6.26 of the Independent Chairmanrs report): 'rln the case of Nigeria, lf it wished to become a contributing Party, it should be invited to consult the tlorld Bank. If it wished to be a Participating Country, much more information would be requested, the major technical consideration being whether it should join OCP or operate its own prograrune. hHO should be invited to discuss with Nigeria what its relationship to OCP should be". Subsequently the Government of Nigeria has decided to operate its own programe and, after several meetings bethreen Nigerian Authorities and WHO (Regional Office for Africa; headquarters), it was deci.ded that WHo should provlde the Federal Government wlth a plan of action for an Onchocerciasis Control Programe, the primary objective being the protection of the Federal Capital Territory (aUu3a area). Since March 1978, hlIIO has undertaken the following actions: - the Regional Director made available $ 150 OO0 from hls Development Fund for supporting activities in 1978. This sum is in addition t.o $ 30 OOO contributed by the Director- General ; - a WHO Onchocelgiasis Mission, corposed of Regional Office and headquarEers experts visited Nigerfland made recormendations to the Federal Government on the organizaEion of the necessary preliminary studies. By a letter dated 13 April the Federal Ministry of Healch of Nigeria indicated the Governmentrs acceptance of the recoumendations of the WHO Mission and requested WHO collaboration in the implemenEarion of the reconmendation; - the services of a WHO ophthalmologist, already posred in Kaduna (project NIE/ESD OOl) has been offered to Nigeria as temporary coordinator of the National Onchocerciasis Control Campaign until such time a suitable national is available to assume that role; - Dr R. I'1. Crosskey, of the British Muserm (Nat. Hist.), who has considerable knowledge and experience of the onchocerciasls situation in Nigeria, and has prepared as a result of a comrission by the Organization a coryrehenslve review of what is known about onchocerciasis and its vectors in Nigeria (see page 2, footnote); - the WHO team based in Kaduna (fnf/VfC.O24) has been reoriented and reinforced: the three entomologists have been trained, by OCP, in the aerial surveys and entomological evaluation; fields of taxonomy, Dr Dunbar, the leading cytotaxonomist working on onchocerciasis vectors, has beeh recruited and will join Kaduna next December; an The issue of thrs document dois not constitute formal pubhcation. lt should not be reviewed, abstracted or quoted without the agreement of the World Health Organization. Authors alone are responsible for views expressed in signed articles. Ce document ne constttue pas une publication. ll ne doit farre l'objet d'aucun compte rendu ou r6sumC ni d'aucune cttation sans I'autorisation de l'Organisation Mondiale de la Sante. Les opinions exprim6cs dans les arttcles signds n'engagent que leurs auteurs. vBcf78.6 Page 2 - archives of the previous activities on onchocerciasis in Nigeria have been traced and a part of it has been found by the Project Leader of the WHO Research Unit based in Kaduna; Ehe creation of a Regional Centre for training of medical and veterinary entomologists(University of Jos) has been negociated and a project proposal submitted Eo the Special Programe for Research and Training. 0n its side, the Government of Nigeria had to underEake the following actions establishment of a base for the National Onchocerciasis Control Campaign; subcontracEing of ecological baseline studies and collection of hydrological data to the University of Ife; subcontracting the socioeconomic studies to Ehe Nigerian Institute for Social and Econo,rnic Research (nf SUn) ; subcontracting the collection of epidemiological data to the Nigerian Institute for Trypanosomiasis Research (NITR) ; submission of a request to UNDP for financial support for breeding siEes. the aerial survey of Simulium 12. ONCHOCERCIASIS AND ITS VECTORS IN NIGERIA Simulirm damnosrm s.1. and onchocerciasis has been known in Nigeria for 70 years. Austen(1909) published the first records of the fly, recording its capture in 1906 at rhe Cross River. Independently, and coincidently in the same year, Parsons (1909) recorded the occurrence of the disease pathogen, then known as Filaria v4Jl4gg, in fou,r Nigerians seen at Lorco1a DuE comlng r-rom Kaooa, Onrcsna ano Toia. , 2.L The disease (see map 3) Despite these very early data, it is not before the opening of eye clinics in rural dispensaries in the Northern Region (tgSOs), that the ophthalmologist F. H. Budden, started to obtain systematic data on the incidence of blindness in rural cosxmunities. It was quickly discovered that severe ocular onchocerciasis occurred in many parts of Northern Nigeria and that cutaneous onchocerciasis was much more widespread than had been imagined. Since Ehen, the best and indeed the only thorough study of the epidemiology of onchocer- ciasis in the former Northern Region of Nigeria (the States of Bauchi, Benue, Borno, Gongola, Kaduna, Kano, Kwara, Niger, Plateau and Sokoto) is that published by Budden (1956). This includes the results of whole population surveys in 15 selected villages, where the prevalence and intensity of 0. volvulus infection were studied, and where a careful assessment was made of the ocular lesions and of the amount of blindness associ,ated wiEh the disease. It is also based on the results of surveys of the blind in a much larger number of villages with the object of revealing the prevalence of onchocerciasis as a cause of blindness. Budden estimated, at that time (L956), that Ehere were about 20 OOO persons blinded by onchocerciasis out of a population of 17 million in the Northern Region of Nigeria. 1 E*Era"t" of Dr R. W. Crosskeyrs report (see chapter I): "An apprai-sal of current knowledge of Simulium damnosum s.1. in the Federal Republic of Nigeria in relation to the development of an Onchocerciasis Control Campaign'r. This report is presently being edited. The bibliography of Ehis report is shown in Annex 1. Three of the five maps are shown as maps 1, 2 and 3. t wcf78.6 Page 3 Estimates of population growths since then, place the population of the same area in 1978 at about 43 roillion. Allowing for the fact Ehat population growth in the areaa lsorst affected by onchocerciasis is likely to have been below average, it may be that there are norr some 3O OOO-4O OOO persons blinded by onchocerciasis in the northern states. Ttris, in turn, irylies that there will be a like ntrmber who are not economically blind but who suffer froo severe visual iryairment resulting from onchocerciasis. Data on onchocerciasis obtained since Buddenrs survey are almost entirely confined to microfilarial prevalence figures. Most of the available figures have been collected during surveys for hr-man tr1panosooiasis and almost all of them are likely to underestimate the true prevalence rate, and none gives any inform"tion on the intensity of infection. Map 3 shows the known distribution of the disease. 2.2 The vectors (maps 1 and 2) Identity Up to now, the studies on the members of the complex in West Africa have been almost entirely confined to the countries of the OCP (mostly Ivory Coast and Ghana), Guinea and Liberia. Ttrere have been no cornparable studies in Nigeria, and nothing ls knoun for Ehe country beyond the fact that S. sirbanr:m and !. dannosuo s.str., the chief vector species, both occurin the Abuja "rea {valGEDlrn6"r, 1Effiiffi some rivers of mid-Borgu (va3ime, unpublished).It is likely that onchocerciasis is transniEted in northern savanna Nigeria nainly by these tlro sPecies (as elsewhere in savanna West Afrlca) and that S. squanosr-m is involved in trans- mission in southern Nigeria, but this needs confirmation. The more southerly speci.es, S. yahense , S. sanctipauli and S. soubrense, probably occur in Nigeria and may also be involved as vectors. The only vectors of h'man onchocerciasis knoriln in Nigeria belong to the c omp lex. Lack of information on the identities of the constituent species Eajor gap in knowledge of the vectors in Nigeria. Simulium damnosuo in S. damnosuo s.1. is a Dis tribution The available data on the distribution of vecEor breeding sites (collected by Crosskey, Davies & Walsh) are useful and sufficient in quantity and quality to al1ow preliminary Eaps to be prepared (maps 1 and 2). However, little or nothing is known of vector breeding sites on the following river systens, where only rapid prospections (if any) have been made: - headwat.ers of Kaduna river and its southern affluent.s; - headwater rivers of the Bunaga and Gongola systens; - headwater rivers of the Hawa1 and Yedseram systems; - headwater riverg of the Gurara systen; - south-flowing river systems from the southern margins of Jos-Plateau; - Pai river system; 1vBcf7}.6 Page 4 southern affluents of the Benue river in Gongola State; - headwaters of the Katsina Ala systeD. Bioecologv. transpission In addition to the broad geographical distribution described above some more intensive studies were made on the bioecology and host-parasite relations of the vectors at Abuja and Lokoja (Crosskey, 1975b, 1958a; Lewis, 1958, 1960) as well as in rhe Kainji area (Walsh, 1970). Vector control Several control schemes have been carried out in different areas of Nigeria (O3i river, 1953 ; Mimi river, 1958 ; Kaduna river, 1956 ; Hawal river, 1963 ). However, the two most iryortant caryaigns were irylemented in the Abuja area (Abuja Control scheme) and around the Kainji dam site. Itre Abuja scheme has been well docr:mented since the publication of its results (Crosskey, 1958b; Crosskey & Crosskey, 1959; Davies, 1963b, 1965,1966, 1968; Davies et al,,1962). It is most iryortant to eryhasize in the present report that Abuja was chosen, against the llawal vaIley region, on the grounds that it was representative of the kind of difficult non-isolated area that would have to be tackled sooner or later , and that it had good comuni- cations and accurate large-scaIe maps were available. The primary objective of the scheme rras to determine whether in the circumstances, j-t would be possible to obtain significant vector control by annual larviciding of the breeding sites. Secondary aims were to determine - should successful f1y control be achieved - whether it had the expected effecE on the incidence and prevalence of onchocerciasis in the area and whether control could be made simple and cheap enough to place on a local footing. Larviciding began in 1956 and a very high degree of "rea1'r vector control was achieved and mrintained over several years. However, from the post-control studies of Davies on the cutaneous aspect of onchocerciasis it is clear that while there was a substantial drop in prevalence over most of the control area, the effect on incidence in children was disappointing; transmission continued despite the extremely low vector densities resulting fron highly effective control (estimated to be an annual average of 95% control). The effects of the vector control schemes on ocular onchocerciasis have been investigated by Rodger (1973), who could form no definite conclusions but considered it possible that the absence of onchocercal blindness in villages along the Tapa river (the southern-most controlled river in the project area) was attributable to the scheme. 2 The construction of a dam across the Niger at Kainji at the beginning of the 196Os, required the foroation of a Unit, financed by the Niger Dams Authority, to carry out control Deasures against S. damnosL@ s.1. Control was necessary Eo ensure that construction work was not adversely affected by the biting nuisance, and that the work force would not contracE onchocerciasig. Larviciding began in 1961 and was continued until 1968 when the dam was coupleted. Walsh (1968) estimetes that fIy density was reduced at Kainji by almost 92%. There was no biting nuisance on the site; no one is known to have contracted onchocerciasis at the construction site and over 50 OO0 local people were afforded sone protection. A very fuII account of the scheme is given by Llalsh (1970). 33 wcf78.6 Psge 5 2.3 lhe socioeconomic aspects Apart from the studies carried out by Bradley (1976) in the Hawal vaIIey, no spec,ific inforruation on the socioeconomics of onchocerciasis is known from Nigerla. There is however a clear indication that the effects of this disease are coryarable to those known from other countries included in the savanna belt of Africa. STRATEGY AND IACITCS TO BE APPLIED IN I'IIE NIGERIAN ONCHOCERCIASIS CONTROL CAMPAIGN .1 Strategy The Representative of Nigeria aE the fourth session of the Joint CoordinaEing Comittee declared: "Onchocerciasis is one of the comunicable diseases to be conErolled in t,he current five years development plan of Nigeria. Ttre prograrme of onchocerciasis control is requested by the Federal Republic of Nigeria for the whole country with intensive operations in the severely affected areastt. The Federal Goverrment has also decided that the highest priority had to be given to the protection of the Federal Capital Territory (FCT) (nap 4) and should the caryaign be planned and irrylemented in phases, the phase I area should necessarily include this territory. 3. 1. 1 Phase I In his report, Crosskey (1978, 1oc. cit.) states about, what he describes as Ehe rnid- northern zone inap 3): "Ttris is tt"EIl.E and most corylex of the endenic zoneg here distinguished. Perennial, or at almost continuous, breeding occurs in the major rivers of the western part of the zone, especially the Kaduna and Garara and their affluents. A very large nr.mber of breeding sites have been discovered during superficial prospection of many other parts of the zone that are thought to be pelaanent (mep 1)". It also appears from our present knowledge of the distribution of onchocerciasis in Nigeria, that this area is, as most of the other onchocerciasis foci in Africa, not isolated and , thus, subjected to periodic reinvasions as was shown by the control caryaign carried out in the Abuja area (see above). Thus, the strategy on which OCP is based will have to be adopted: the extent of flight of the female vector of the savenna cytospecies mrkes it necessary to treet fairly large areas; the longevity of the parasite in man (15 to 20 years) and the lack of therapeutic Eeans of control make it necessary to pursue an entooological control canpaign over a very long period. Linits of the phase I aqea (rnap 4 ) In order to reduce to a rainiur.o the relnvasion phenouenon in this non-isoleted zone, the limits of the phase I area will have to be designed as follolrs: - in the north the limit of the phase I area will have to correspond to the northern lfunit of distribution of the disease and lts vectors in the oid-northern region of Nlgerla; the southern linit will correspond to the border, if any, between: the savanna and forest t;lpes of onchocerciasis; the savanna and forest species of the s damnosr@ complex; the western and eastern limits will have to be far enough from the FCT in order to include the entirety of the breeding rivers situated at a distance compatible with the reinvasion of this territory and surrounding zones. vBcf78.6 Page 6 The surface of this phase I area can be estimeted at 2OO OOO km2. It corresponds to the concept of thetrminimal surfacert which, in accordance to our present tactics, has to be envisaged in any onchocerciasis control campaign dealing with savanna cytospecies of the damnosr.m complex.S 3.I.2 Phase II (map 4) Ttre delimiEation of the phase II area is much easier to define - northward, the linit of the phase II area will correspond to the northern limit of distribution of the disease and its vectors; southward, the limit will correspond to the border, if any, between Ehe savanna and forest types of the disease and it.s vectors; Ehe eastern limit will correspond to the western liuit of the phase I area; the western lirnit will correspond to the eastern border of the OCP in Benin (present phase III east area and southern extension). 3.1.3 Phases III and IV (nap 4) A11 the foci locaEed, in Nigeria, eastward of the phase I area will have to be included in Ehe Control Caryaign. A provision has been made for two successive phases buE further studies nay lead to the conclusion that the operation, in this zone, could be irylemenEed in one phase only. 3.2 Relations with the OCP Despite its contiguity with the OCP, this prograrme cannot, for the following reasons, be envisaged as an extension of this first project: - with the southern extensions implemented or planned in Ivory Coast, Ghana, Togo and Benin, the OCP has already reached its maximurn possible size as far as circulation of data, technical and administrative instructions, personnel, etc. is concernedl the OCP has already reached its naintenance phase, phase III areas having been under treatment for already t\.ro years. However, it can be expected that the experience gained in the OCP could be Eransferred to the Nigerian Prograrmne (craining, rnethods and techniques, expertise, exchange of data, etc.). 3.3 Tactics The sEructures of the OCP, the methods and techniques used in this progranmre could be adapted to the Nigerian Prograrme as Ehey have proven to be valid especially as concerns: - direction and technical units; - methods of treatment (aerial applications); - insecEicide selection and efficacy; - methods and structures of evaluation; - entomology: sectors, sub-sectors, radio-cormnunications, etc. ; - epidemiology: simple and detailed evaluation; - hydrobiology. awcf 78.6 Page ',1 4. PIAN OF ACTION FOR TIIE PRXLIMIMRY PHASE In order to design a precise plan of the Control Caryaign, further studies will have to be organized and irylerented. Ihese studies will be concentrated in the phase I area and progressively extended to phases II, III and IV areas. 4.1 Studies to be carried out (i) EnEomology: - delimitat,ion of the boundaries (3.1.1) between: (a) forest and sevanna cytospecies of the S. damnosum co4lex. Ttrese sEudies will fix the southern limit of the Nigerian Control Caqaign, especially souEhward of the phase I area; (b) phase I and Phase II; (c) phase I and phases III and IV areas. Ihe northern boundary of the Programe will have to be determi.ned. Ttre results obtained will determine the linits of the phase I area in which the follotring activiEies will chen be concentrated: - location of the breeding siEes of S. damnosum at the different seasons; - study of the vectors populationsr dynamicsl - study of the transmission dynamics; - estination of the susceptibility level of S. damnosum to Temephos and alternative insecticides. (ii) Epideniology: - delimitation of the phase I boundaries (see (i)), especially in the south and south-erest; - assessnent of the leve1 of endemicity and of the severity of the disease in selected villages of the phase I area; - collection of existing data in the rem-ining areas. (iii) Hydrology: - collection of existing data (struccure of the present hydrological network, quality of data already available) ; - planification for irryroveoent of the nunber of sEations and quality of data. (iv) Hydrobiology: - collect,ion of basic data in the differenE basins; - selection of monitoring poinEs. (v) Soci-oeconomics: - collection and analysis of existing daEa. The analysis will concern.existing and planned development programes with their actual relation with onchocerciasis. wcf78.6 Page 8 4.2 Training The training of the necessary personnel (Annexes 2 and 3) will have to be planned and undertaken as soon as possible. Ttris training could be provided by the following institutions: - University of Jos (Regional Centre for training of medical entomologists): entomology; - University of Ife: hydrobiologY; - Ahmadu Be1lo UniversiEy, Guinness Eye Clinic: ophthalmology; - the OCP: entomology, parasitology, ophthalmology, aerial operaEions, administration, general mrnagement. 4.3 Structures of the P.og..-.l The following structures, based on the experience gained in the OCP, are proposed (see Annex 2). (i) Headquarters: The office of the Prograre Director, the headquarters of the VecEor ConE.rol Unit, Ehe Epideniological UniE, Ehe Economic Development Unit, the Administrative Services will be based aE Kaduna. (ii) Entomological sectors and sub-sectors: Itre enEonological sectors and sub-sectors will be located throughout the Prograrme area: - phase I area: two sectors and eight sub-sectors (see map 4) will be located as follors: - Minna sect,or - Minna, Kafanchan, Keffi, Abuja sub-sectors; - Lokoja sector - Lokoja, Bugana, Abaji, Pategi sub-sectors; phase II area: two sectors and seven sub-sectors are anticipated (north and south); - phase III area: two secEors and eight sub-sectors (souEh-wesE, norttFeast); - phase IV area: one sector and four sub-sectors. The locations of sectors and sub-sectors of phases I1, III, IV areas will be precised during the preliminary studies period. (iii) Aerial operations bases: Thro bases will be necessary. Iheir location will be defined during the preliminary studies period. 4.4 Time-table The following tioe-table is proposed: Year 1 - Selection, training and recruitment of the Progranme Director' - Selectlon, training and recruitment of headquarters and phase I personnel. I 'Ihe present report does not sho,r^r the necessary super-structure which will have to be organized by the Nigerlan Government, for Ehe direction of the Progratme. I a Year 2 Year 3 Year 4 vBcf78.6 page 9 Settlement of the headquarters. SettlerenE of the turo sectors and eight. sub-sectors of the phase I area, Ordering and purchase of equipment (cars, Iaboratory and field equipment, radio, etc.). Organization of relations with collaborating instiEutions. Starting of the preliminary studies in the phase I area. Selection, training and recruitxoent of phase II personnel. Settlement of two sectors and eight sub-sectors in the phase II area. - Coqletion of the preliminary studies in the phase I area. - Starting of the preliminary studies in the phase II area. - Selection, training and recruitment of phase III (possibly IV) personnel. - Settlernent of tsro sectors (possibly 3) and eighr (12) sub-secEors in Ehe phase III(possibly IV) area(s). - PIan of operation for the phase I area. - Preparation of the control caryaign in the phase I area. - Starting of the phase I operations. - CompleEion of the preliminary studies in the phase II area. - Starting of the prelininary studies in the phase III (possibly IV) area(s). 4.5 Proposed support from institut ions outside the Proqrame (see Annex 2) The following insEitutions are expected to provide support to different phases (preliminary studies, control caryaign). the Programne during the 4.5.1 Nigerian Institutions - NITR: Research (entomology, parasitology) Collection of data (epidemiology) - TTD: Aerial operations expertise - Ahrnadu Bel1o University: Training (ophthalmology) - Jos University: Training (entonology) Research (entoruology) - Ife University: Hydrobiology Hydrology - Ibadan University (NISER): Socioeconomics - Water boards: Hydrology vBcf78 .6 page 10 4.5.2 tlorld Health Organization - WHO, Vector Biology and Control Research Unit (IGduna). Although this unit will continue its studies on the bio-ecology of vectors (i.e. malaria) its staff has been trained and a specialist in cytotaxonomy has been recruited in order to provide the best possible scientific and technical suPPort to the Progranme: - cytotaxonomy (distribution of the different cytosPe cies of the S. damnosum corrylex); - insecticide trials (including suscePtibility tests); - distribution of breeding siEes; - vectors populations dynamics; - transmission dynamics. - WnOfltufESq/OOl (Kaduna). This unit could provide support in the field of ophthalmology. - OCP (see 4.2: Training). 4.6 Requirements Annexes 3 and 4 show the respective requirements for 4.6.L Personnel (Annex 3) necessary in headquarEers and for phase I for the two main techni-- cal units (VCU and EPI). Personnel of the Directorrs office and staff required for the economic development and administrative units (whose structure w111 be decided upon by the Nigerian Government) will be in addition Eo the VCU and EPI staff. As more sectors and sub- sectors are incorporated in the prograllme (phases II, III and IV) additional staff will be required as shown in columns 3 and 4 (sector) or columns 5 Lo 12 (sub-sector) of Annex 3. AparE from the Chief of the Unit, the staff requirement for EPI will be doubled for phases II, III and IV operat.ions. 4.6.2 Equipment (Annex 4) necessary for the direction and Ehe administrati-ve and technical units for headquarters and for phase I. As more sectors and sub-sectors are incorporated in the progranme (phases II, III and IV) additional equipment will be required as shown in columns 3 and 4 (sector) or coluons 5 to L2(sub-sector) of Annex 4. Fifteen Ehousand litres of Temephos (Simulium formulation) have already been purchased and will be used for experimental treatments carried out in the phase I area during the first three-year period. l'l vBcf||.6 Page 11 ANNEX 1 REFERENCES Austen, E. E. (1909) Illus trations of African blood-suckine flies other than mosquitoes and tsetse-f1ies, British Museum, London , xv + 221 pp. Bradley, A. K. (L972) The effect of disease on rural economy, social structure and sett.leoent.; A case study of onchocerciasis in the Hawal va1ley, Nigeria. Unpublished mimeographed documenr wHo/oNcHo/7z.93, l1 pp. Bradley, A. K. (1976) Effects of onchocerciasis on setElement in the middle Hawal valley, r. Soc. trop. Me{. Hyg., 79, 225-229Nige ria, Trans. Budden, F. H. (1955) Incidence of human infecEion with onchocerciasis in different cmunities 39, 32L-332in relation to Ehe incidence and type of the ocular lesi.ons, Br. J. Ophthal. Budden, F. H. (1956) The epidemiology of onchocerciasis in Northern Nigeria, Trans. r. Soc. rrop. Med. Hyg. , 50, 366-378 Budden, F. H. (I957) NaEural history of onchocerciasis, Br. J. Ophthal. , 4L, 2L4-227 Budden, F. H Trans. (1963a) Comparative study of ocular onchocerciasis ln savannah and rain forest, r. Soc. trop. Med. Hyg. , 57, 64-70 Budden, F. H. re lati on endemic, Crosskey, R. med. J. (1963b) The incidence of microfilariae in the eye and of ocular lesions to the age and sex of persons living in conrmunities where onchocerciasis Trans. R. Soc. trop. Med. Hyg., 57, 7L-75 W. (1954a) Onchocerciasis in the Galma va1ley area, Northern Nigeria, I.I. Afr.(n.s.),8,75-79 1n 1S Crosskey, R. W. (1954b) Infection of Simuliun damnosum with Onchocerca volvulus during the wet season in Northern Nigeria, Ann. trop. Med. Parasit. , 48, L52-L59 Crosskey, R. W. (1955) Observations on the bionomics of adult Simulium damnosum Theobald(Diptera, Simuliidae) in Northern Nigeria, Ann. trop. Med. Parasit. , 49, L42-L53 Crosskey, R. W. (1956) The distribut Trans. r. Soc. trop. Med. Hyg ion of Simulium damnosum Theobald in Northern Nigeria, 50, 379-392 Crosskey, R. W. (1957a) Man-biting behaviour and infection with developing filariae, in Simuliun bovis de Meillon in Northern Nigeria, Ann. tro d. Parasit., 51, 8O-86 Crosskey, R. W. (1957b) Further observations on infection of Simuliurn damnosun with Onchocerca volvulus in Northern Nigeria, Trans. r. Soc. trop. Med. Hye 51,541-548 Crosskey, R. W. (1958a) The body weight in unfed Simulium damnosum Theobald, and its relation Eo the Eime of biting, the fat-body and age, Ann. trop. Med. Parasit.,52,149-L57 Crosskey, R. w. (1958b) First results in the control of Simulitrm dannosum Theobald (Di Ptera,Simuliidae) in Northern Nigeria, Bu11. ent. Res., 49, 715-735 Crosskey, R. I.I. (1960) Distribution records of the black-flies (Diptera: Sinuliidae) of Nigeria and the Sout.hern Cameroons, with a key for their identification in the pupal s tage, Jl W Afr. S9i. Ass., 6, 27-46 vBcfl8.6 Page 12 Annex 1 Crosskey, R. W. (1962) Observations on the uptake of h 'man blood by Simulium damnosum: the engorgement time and size of the blood-meal, Ann. trop. Med. Parasit. , 56, 141-148 Crosskey, R. W. & Crosskey, M. E. (1958) Filarial infection in Simulium griseicolle Becker Nature Lond. , ]11, 713 E. (1959) A quantitative survey of onchocerciasisCrosskey, R. W. & Crosskey, M. under twenty years of age Parasit. , 53, LO-24 in an endemic area in Northern Nige ria, Ann. trop. in persons Med. Davies, J. B. (1963a) Further distribution records of the black-flies (Diptera: Simuliidae) of Nigeria wit.h notes on the occurrence of Simulium damnosum Theo. in abnormal situations, JI W. Afr. Sci. Ass., 7, L34-L37 Davies, J. B. (1963b) An assessment of the insecticidal control of Simulir:m d:mnosum Theobald in Abuja Enirate, Northern Nigeria, from 1955 to 1960. I. The effecr on the prevalence of onchocerciasis in the human population, 161-181 Ann. trop. Med. Parasit. ,57, Davies, J. B. (1965) An assessment of the insecEicidal control of Simulium damnosum Theobald in Abuja EmiraEe, Northern Nigeria, from 1955 to 1960. II. The effect on the incidence of Onchocerca larvae in the vector, Ann. trop. I'led. Parasit , 59, 43-46 Davies, J. B. (1966) A report on the Simulium Control Scheme at Abuja, Northern Nigeria and its effect on the prevalence of onchocerciasis in the area. Unpublished mimeographed documenr wuo/oNcHo/66.54 Rev.l (.trn/oncn/11 Rev.I), 29 pp. Davies, J. B. (1968) The Simulium Control Scheme at Abuja, NorEhern Nigeria, and its effect on the prevalence of onchocerciasis in the area, Bull. Wld Hlth Org , 39, L87-2O7 Davies, J. B., Crosskey, R. W., Johnston, M. R. L. & Crosskey, M. E. (L962) The control of Simulium damnosum at Abuja, Northern Nigeria, 1955-60, BulI. WId Hlth Or .r 27, 491-510 Duke, B. O. L. (1968) Studies on facEors influencing the transmission of onchocerciasis. IV. The biting cycles, infective biting density and transmission potential ofItforesttr Simulium damnosum Ann. trop. Med. Parasit. , 62, 95-106 Dyce Sharp, N. A. (L926) A contribution Eo the sEudy some observations on its prevalence in Nigeria, 3 73- 388 of Onchocerca volvulus Leuckart, \.rith Trans. r. Soc. Erop. Med. Hyg ,T, Grenier, P., Mouchet, Cameroun, Bu11. J., Rageau, J. & Adam Soc. PaEh 54 Ikejiani, O. (1959) A laboratory epidemiological study of certain infectious diseases in Nigeria, ht Afr med J. (n. s. ), g, 37-42 txoe , J. P. (1961) Simulies de la R6publique du 1131-1143 vBcf7|.6 Page 13 Annex 1 Lewis, D Ann J. (i958) Observations on Simulium damnosum Theobald at Lokoj in Northern Nigeria, tro . Med. Parasit., 52, 2L6-231 Nnochiri, E. (1964) Studies on Ehe epidemioloSy of onchocerciasis in Ehe Ibadan area of western Nigeria, W. Afr. med. J. (n.s.), 13, 139- 150 Nwokolo, C. (1950) SEudies in onchocerciasis (A review of Eastern Nigeria), Trans. r. Soc. trop Med. Hye , 43, lOO cases from Enugu District of 493-501 the distribution of Simulium Unpublished mimeographed document parsons, A.C. (1909) Filaria volvulus Leuckart, ils distribution, structure and pathological effecrs, p"r.ritoliGilI6EJ359-368. ffni" paper has been wrongly d.ated by most auEhors as 1908. It appears in Ehe journal part nominally-for December 1908 but not issued until 11 March 1909 as stated on the original covetJ Philippon, B., S6chan, Y. & Bernadou, J. (1969) Map showing damnosum in West Africa (situation in October 1968). wno/ollcno/6g.73, 5 + viii pp. Rodger, F. C. (1973) The Simulium Control Scheme at Abuja, North Nigeria, and its effect on Ehe prevalence of ocular onchocerciasis, Trans. r. Soc. trop. Med. Hyg. , 67, 225-237 Simpson, J. J. (1912) Entomological research in British West Africa. II. Northern Nigeria, Bu11. ent. Res. , 2, 3OL-356 Vajime, C. G. & Dunbar, R. W. (L975) Chromosomal identification of eight sPecies of the subgenus Edwardsellum near and including Simulium (Edwardsellum) damnosun Theobald(Diptera: Simuliidae), Tropenmed. ParasiE., 4, 111-138 Walsh, J. F. (1968) "Fifty years of applied entouology in Nigeriarr. The Simuliidae and'their control with special reference to the Kainji control scheme. PP. 101-106 in Fifty years applied entomology in Nigeria , pt II (being the Proceedings of a conference of the EnEomological SocieEy of Nigeria held at the Nigerian Institute for Trypanosomiasis Research, Kaduna, 25-28 March 1968) Walsh, J. F. (1970) The conErol of Simulium damnosum in the river Niger and its tribuEaries in L969.relation Eo the Kainji Lake Research Project, covering the period 1961 to Unpublished mimeographed documer^t eOf7O,4, 33 pp. w tt, 65 ya G. B. (1971) Onchocerciasis in Ibarapa, Western State, Nigeria, , 5L3-523 Ann. trop. Med. Parasit. vRc/78.6 paSe 14 ANNEX 2 m o op! t ;d o o ! o!E dH z I o c o F ca I o H o o ;r o 6 ! o ol <HI Hl I I u@oo ooEEoo Xtriul o o .rlvv ol!l s!ol c o >l .r L .al t ddl .d of,l d al!oal? dot rl rr I o o o E d .Ea o o d .i d HH I d !d o 4 ! o 6B I o E o o = I (( qx om o ooI .t.eo !E!ood ooo il.ioiQdl a ooF{l cd ovHI zltr I aHQHHZa5 &c) ozd,4&H 2fi,40H€fir()JHOzo o o o o o o I H o H I @ o o !5 I ts H z E o oHEozooH lDe = oo .io o 6od.rq o Qq o o oq .i o4S o Jio ittt zoH H frtr Hz H Eo Qo!trooo tr o.il QO la a o 6 ac! c rs o.i I ! lttt E! o t o I So H :iH oH tu H @r o o o.i Orq600 lqa ! ! cq ad oq o oo 6 lttt H H H H H o 6 A ioo m.r oo s.i< oqoJqEOO 6.i oEaaudo -c k trqQ6 0qo ao d tttt f o o lo o6 ,Eda d H o E c H a EI =E d o c A O d d ( o 6 @ GO .io KJ!oo ode oOuoldu 1 2 A 6qu !e d E ,la t 4 0E u ! ( ol o d .r uo q c.i ul o,i o o! il d u olr o o oS I !.i Ol O.i 6 6o E ^ o c ol E co ..d! lo! . 6q u o 4 0 Hl dlu ci Fq ,-q q +4 o I trlc odq o-i oo€u ol ql oua6 J o r ri gl Eli$ro 'iirttAl tl ts o o i qo !! o Hl oHluHlu>Hl o Hl o i lolo ol o ol o o ol ol6l N dl N 6Et ,Et cAlrtulrtu z() H =d JocHzoo q Hq socItloI ozo z H dEoHz H H ts E& Po5dH AHq A &tu x E o oioootol d .n oOl .n!oOl tr H o'.io.r dau ,HXO oErH@ 6 d t2 3tolxlual o6ladl o -!EHliHl d zlE .4Nc) o 6 o E"q gr > H 6 -! Et eo or o d 6O Er O Et u o i..i .q dr ! Et o c o kV !-r O dt O 6 u . 9l o 6 0r E 4 0 0 "al [i Ji gi .1 E 8dx\ r.d(! rr 40 .i@o()l Ol ! r I G * o ! .d.dal ol q, it .r 6 > G E p>l .Cl o g dr o , o; 6 g sl .ii b,5i u3i3.E3El Hr ! o .rt o >, o i tr3l ,r o . !r o o @ tu u Hdr O.i 'it tot >v €t o I I I I . 6l Ot CrHtt<to trH z oaz@Hqu o<tudoodatu< OFrEO3(J YBc/?8.6 Page 15 ANNEX 3 6! H illld-6dl6NdioooioN@onoo+NoI Q in N ,jg H$ @-4 Nts $l NN a66b NJJd F I4 -;6o'fs! .\Y N oJ I o o a NN cd ,E a d E 0 o Nr u6 o,on q NJilH N J6 6 a - u o{ @ NF Hq'O.-!oUIoo4il ir rd \l'dd-rdtNt Bcu,Ji dl rd .t'li\tHdNi alr o Fq, ao I!qt ot tlJlooJihNriidrJlN.+li6tNNd o c c o6k o tu k oo HEqo ot tr -o kv !\ d ko9kudo .r u.d o d.r u.dE O OO.r ! X o !5r oq @ r.i-dodq.dda-\ !q E o o o xo ooi!ooo-u'io0d.d@(!tr-\E& tq.d o, 'rl (! ord oO ! G a . o !-C > H oH .r! H C.O k O O.i 6 OA{ .d Ad 0, G 5i O H J otsI oOF.oFlzo=a(J= o >! o q,EdoEAKooro El o!>I O }\! u od u! ho o>F t!uEa!o.H-t6!6oo.rdr!-\uo .r.dCi!i€'o.i oou!6.ioco-\-E .io !ooc.lxQdooo oh cJrr6oJoE .do @u ooo!.i(! 6!CEtd-\ tee@c o!o6 0 JEooo.i.c.dqu!.>.F9op ! ! 4 olEl 6 o o o.r E o 6 Oo c c o o d d ! o o o ltr 5 0 > Ertd<ErFlda>E<o<(J()E I N o 6 .t o 6 A ! 6 ! o! !(n aq !d o q FH 2 >f 3 oJo rA Ao oz FIod tizoO &IoItl &ok udH g & dzz od E] Oi N I d o H odos o'iEdoota o6o d< .io HKo!sd .io z<) ( u o ts oo-t+o o\+o@r o oNrrd J oNJ i o o\t\too NJJJO4Q ON O\tr i$ @-@ -t :qo _;H --a \' od66 -\< a -1 -'d *i s oqoo\\v { dt d(! dI o q i -+ U6 oa \<q 6 c = o @ $ G oI J H o o o @ d k oo H6 o .E ooNdo rN-t$r oON J -Ni J o 8 o JNdI N NNNidiINilNNN -$i ri J \j.i ri J ilO6\t tEU: o= rb;ri9t *1 U c o ao ad H Hd ol o Ll d x dl d ol .iLlo o ol o a ol o cl o dl o o cl ! o ol o .r !l i cl d .o .il! u !E 6l d - El o u!tr .loa O^ ^ O E ^ r ^^ OH O d A A =l O 6 d 6 d O O!l@ ! H I O ' >l .r .i o I ji E .i .dEl t d O o d vl O -d El ! oE ,Colou Eh o o I o o d ul .6N o 6 o o "Eld H O C . ! ul O 6 -C^ CIO o . . Elo 6 G d oold o Goi o o cl 0 E o\t alo uio old e 6 u .ilE f O v.d !, ol o ! H EIO^ ovv .il.i N o o ,lvv o o E o o El o o o s o I o c o ulE tr s o0 rot 6 a 6 N O Al O lr N ! tr i ! .ilo o . o 6l o .J c c > - JolooloE!!otr .dlroo6.i!o 51600k !l 6h.n .rko olE E g tr o d o (! ,l o.r o I ! 6 Hr ol-\ E o ul E o! u o p -cil(,drJ!J!r oloEko6u6v olroo! ol o6 Gcf(!lri6Hdrqi ol ooqsi!! lvo-od .rl Mor oo! o(ol r r E H o r o Io o I .i , o o o ol 6 I F 6 cl E o a .4.A.A d .if!!!(dooou .l HHokoaaE alo\oo ! .il.ruoot!c .i Of{JO.OO'dCr.d qtl.iuOOd dO .ild !6O O dl>!ddrua 4 =fooorzooat .rlEoado (Jk rqlE o9 H <lr.tuo@a@tu h EOko o 'io.r(!k 6t.l6J i 6!qv(oo €€ > oo.duHo5 H k (!Oo .El O^o .r c @ ara o )4 o o od.i! o E tr No ! r o 6 tr'dv.d &.E H O o €c, ro tx E .J I xv H i Ok o o.! ! oJ .il uada Hoad Eo doo, E d >-l (JkFtE @ d q k n,q) N vRcf78.6 page 16 ANNEX 4 @ N FIzo AH =o E I H E6 flA A2 @&HHd q A4 rd :d z 4 P{5 Flo&H v o q Hq HodEoo o4 7co(, Hz a N I JiNdNNN vBcf7l.6 MAP 1 Page 17 The geographical distribution of known breeding sites of Simulium domnosum s. L in the river systems of Nigeria. (From data available to 1977). Rivers that normally flow only in the wet season are shown with broken lines. See text for further explanation of the symbols used. The dotted line around the Jos Plateau represents the 1000 metre contour. Ouery marks indicate improspected rivers in which breeding is expected to be found or near known onchocerciasis foci. I fz ! i,:-. ,..";. -,'.Lrj --\ ,-lgrsef ' J od ',.;o. G) ")r--- '. I lI oItu N * 67.t .:6 oLO --t .:o o! -sE -Eo: -UoBo9fo.=c-E =-c)E T.E cgrri .Era'ET.a:EE9 -oEt!o!.o =l =J il 4U 9 z E *r*r, I \.-- r' '---:--'- ''l a ,r_.n I t vBcf7} .6 Page 18 MAP 2 The geographical distribution of breeding sites, and of capture sites of adult females other than at known breeding sites, of Simulium domnosum s. l. in Nigeria in relation to simplified basic geology. (From data available to 1977). Sedimentary/alluvial areas unshaded and contrasted with precambrian basement complex that has not been inundated by the sea. 100 km Sedimcntaries ^ Adult f lies found man-biting at srtes other than known brecding sites o Natural breeding sites O Man-made breeding sitesPrccambrian (volcanrcs included) wHo 7E846 t o & a \ I 6p o@ a 0 a a wcf78.6 Page 19 I i MAP 3 The geographical distribution of human onchocerciasis in Nigeria, with an approximate indication of prevalences and outlines of the major endemic zones (From data available to 1977) F.C.T. : Federal Capital Territory. tw 100 km o 0nchocerciasis not found (Budden, 1956) o Low prevalences . Moderate prevalences lD High prevalences (with scrious onchocercal blindnes) '...'.."' 0utlines of main cndemic zones State boundaries WHO 7EE1E t 1 GONGOLA c+4 "'i "" a. o EAUCHI,I PLATEAU ... F C.T. a o o o BORNO o 3 'l o 2 o a a aiOj aI. o o ? ,ur ''s o o KANO o o I I I oo o /. o oo 't tri -i, o o o o N IGER '' aa o d / KADUNA a;'.-.. .......... oo /d r-O(OO O:. , -6', .J \ .lo o o O6 - soKoTo I ) 95. '.- .1 XWARA 5 a OGUN BE NOE L a ? a oNoo \1 -o ^tt a ^/ ,t ,t I at ANAMBRA ) t\ - - i t'- - t 'l- a o oa a i cRoss RIVER -r IMO I i- -r nrvens ) EENUE a I a I vBcf7}.6 Page 20 MAP 4 DISTRiBUTION OF PRELIMINARY STUDIES AND CONTROL AREAS N t oItu ! i6(,g EE@'= E!-',EtE8EEiocfIuJt ffist a ) o G -c CL o lJ- a eUI z o Y otr\ !1 \ G , ( f f'".o\'Y, o GE o . i./lll ".i.. 6) (o I * B t E \.1. '4 \,b q, ag 4i, 6, ""t a) ,(6 ,lge ,r";i,.--.-- I II I o\ "rl'-- '+d c GI Or -tl -31 \ .: I E >=M*r,