Feasibility of an onchocerchiasis control campaign in the Senegal river basin area (Republics of Guinea, Mali, Senegal)

JOINT COORDINATING COMMITTEE Onchocerciasis Control Programmg in the Volta River Basin Area Ofice of the Independent Chairman c/o World Health Organization l2ll Geneva 27, Switzerland Tcl. 3.t6061 TclcrL( 27821 J.C.C..C.C.C. COMITE CONJOINT DE COORDTNATION Programme de Lutte Coutre I'Onchoccrcose dans la Rdgion du Bassin de la Volta Bureau du Prdsident Indlpendant c/o Organisation Mondiale dc la Sant6 l2ll GenCvc 27, Suisse T.l 34@61 T.lex)Ciltt5 27821 JCC5. 9JOINT COORDINATING COMMITTEE Fifth session Lom6, 5-8 December l-978 22 November Ig78 Provisional agenda item 12 The Independent Chalrman submits for the consideration of the Joint Coordinating Committee, at tts fifth session, the document "Feasibj.J.i.ty of an onchocerciasis control campaign in the Senegal River Basin Area (Republics of Guj.nea, I\lali and Senegal-)". This document has been reviewed by the Steering Committee which has made the following conments ttI If the study is to examine the justification of establishing a new control programme, it should examine, in addition to the matters referred to in the Plan of Actj-on: a) significance of onchocerciasis relative to other causes of morbidrty and mortality in the area; b) current health prograrunes rncluding level of expenditure and type of service; national health strategies of the Partici,pating Countrj-es, including prrority to be grven to the control of onchocerciasis; c) in terms of the economic development benefi.ts, the significance,role and priority of increasing the availabillty of land in the context of national development strategies; d) the advantages and disadvantages of establishing a separate programme from the OCP including possible economies of scale, duplication of management structures and possible dilution of scarce expert]-se. II As to the programmes's possible effect on the OCP, the Steerrng Committee considers that this should be examined further inc 1ud j.ng : a) Ii.kely effect of level of larviciding needed in the OCP; b) likely financial implications of the new programme for the OCP; c) possible alternative ways of supportj.ng OCP (e.g., adulticrding, partial extension to the West)." WORLD HEALTH ORGANIZATION ORGANISATION MONDIALE DE LA SANTE wcf ta.s Jcc 5.3 Ce document ne constrtue pas une publrcatron ll ne dort farre I'oblet d'aucun compte rendu ou r6sumd nr d'aucune crtation sans l'autorrsatton de l'Organrsatron Mondrale de la Sant6. Les oprnrons exprrmdes dans les artrcles srgn6s n'engagent que leurs auteurs. FEASIBILITY OF AN ONCHOCERCIASIS COMROL CAMPAIGN IN THE SENEGAL RIVER BASIN AREA (REPUBLICS OF GT,INEA, MALI, SENEGAL) The rssue of thrs document does not constrtute formal publrcatron. lt should not be revrewed. abstracted or quoted wrthout the agreement of the World Health Organrzatron. Authors alone are responsrble for vrews expressed rn srgned artrcles vBcf 78.5 Page 2 1. INTRODUCTION The Republics of Guinea, Mali and Senegal have, for many years and on many occasions, requested that Ehe Onchocerciasis Control Prograrrne at Present being implemented in seven countries of West Africa should be extended to the areas of these countries where onchocerciasis is knor,rn to be as serious a health problem as it is in the OCP zone. The last official request was made at the 4th session of the Joint Coordinating Conmittee of the OCP (Kuwait, December L977) where Senegal and Guinea were invited as observer, Mali being already one of the OCPrs seven countries for its south-eastern foci.l The decision of the JCC was (Independant Chairmanrs report, p. 13): 6.26: "WHO should be asked to conduct joint studies in Guinea, Senegal and additional areas in Mali not included in the OCP report. The JCC noted with satisfaction the Regional Directorrs offer to carry out these joint studies and expressed the hope that WHO would find the necessary funds as soon as possible. In thaE way, the necessary information would be available for the JCC rs next session and no time would have been wasted.rr . 6.27: 'rThe JCC accepted this proposal." 6.28 "The UniEed States representative said that if WHO wlshed to carry out the joint studies in the Senegal River Basin, his GovernmenL would be willing, entirely outside the Programne, to consider making a contribution in the form of consultants or other assistance that might be needed". Since December L977, i.n accordance with the instructions of the JCC, WHO has undertaken the following actions: - The Regional Director made available $ 150 OO0 from his Development Fund for supporring activities in 1978. This sum is in addition to $ 3O OOO contributed by the Director-General. - Creation of a comrittee, composed of Regional 0ffice and headquarters specialists, in charge of the preliminary studies and planning. - Creation of a field team, composed of an epidemiologist and an entomologist in charge of collecting the existing data and organizing some preliminary surveys. - Misslons of specialists from headquarters and Regional Office for discussions with the national authorities and coordination of the activities. - Interviews of candidates in the countries and organizaLion of their training in the different disciplines and at different leve1s (12 Guineans, 3 Senegalese). - Recruitmeng of a temporary adviser in charge of producing a synthesis of the available entomological and medical data in Senegal and Mali. - Recruitment of a temporary adviser in charge of producing a synthesis of the socio- economic data available in the three countries. Orgar.izati-on and implementation (September 1978) of aerial surveys of the entire areas of western Mali and Senegal. 1 ' During the last World Healch Assembly, the Republic of Guinea-Bissau officially requested to be included in this Progranrne. wcf ta.s page 3 2. ONCHOCERCIASIS IN SENEGAL, WESTERN },IALI, GUINEA AND GIJINEA-BISSAU The studies already made in these countries, if far from being sufficient for a control campaign to be planned and implemented, give a clear indication that onchocerciasis is, in the savannah areas (see map 1) as serious a health problem as it is in Ehe OCP area. The prevalence of the disease reaches its hyperendemic level (more than 60%) along all the main rivers and cributaries except on the Senegal s.s. (Kayes area), the lower-Bafing and the lower-Bakoye which represent the northern limit of distribution of the disease and its vector in this region of West Africa. Ocular lesions and blindness due to onchocerciasis are thus widely distributed in the hyperendemic areas. In his synthesis for Senegal, Dr Philippon writes (p. L2): 'rIn practice, the entire population (more than 90%) more than 15 years old carries 0. volvulus microfilariae . The first cases of blindness due to Onchocerciasis appear after the age of 15 years and affect one person in five in the adult. population. In the Gambia Basin, the maximum rate of blindness reaches 11% . . .". The transmission levels can be extremely high in the hyperendemic area and, to give an example, the maximum transmissi.on potential known in West Africa (including that of the OCp.r) has been found on the Niokolo Koba, a tributary of the river Gambia, where, in one month, the transmission reached 3ooo larvae (tolerable level: 1oo larvae per year.r). Our knowledge of the distribuEion of the breeding-places of S damnosum (mainly obtained during the recent aerial surveys implemented by OCCGE and WIIO in September 1978), although i.ncomplete, shows that these places are widely distributed on the m:in rivers and on most of the permanent or non-permanent (rainy season) tributaries. In the savannah area, the cytospecies involved in the transmission are the same as those in the OCP zones ( S. damnosum s. s. ; S. sirbanum). With the exception of the northern zone in Mali (Kayes), where a high Percentage of the flj.es are zoophilic, the dynamics of fIy populations shows no difference from what is already knovm from other savannah areas, including the OCp. One aspect of the vectorst population dynamics has to be emphasized: the problem of re ].nvas 10n. rn the ocP area, the periodic reinvasion of some of the treated areas, principally the \,restern and south-western zones in I'Iali and Ivory Coast, has been the main technical problem from the beginning of the Progranrre and the mein concern of the recipient and donor countries. The extension of treatrnents in lvory Coast has greatly reduced this problem but some of the newly treated areas are still reinvaded during the rainy season, thefIies, belonging to savannah cytospecies, coming from non-treated savannah zones located westward or southward, i.e. in Guinea and possibly western Mali. For the new zone presenEly under consideration, this problem will not exist as the area will have to be designed so as toinclude the entire zone where S. damnosum savannah cytospecies are breeding; (the western, south-western and southern limits of the proposed areas are presently under study but they canbe expected, from already available data, to be as shown on the maps attached). This zone will present the following advantages (see maps 1 and 2): (i) The northern limit of the vector and disease distribution is well known, as it wasfor the OCP; (ii) The prograrrne will be contiguous with OCp, rhen - ocP will be protected from reinvasion from the west and south-west; - This Programne will also be protected from possible reinvasion from the east; (ii-i) This progrartrne area will not be subjected to reinvasi.on from the west, south-west and south for the reason already described. This progranrne will thus be very isolated from any reinvasion and will, the results obtained in the western areas of the OCp. moreover, improve wcf ta.s page 4 Socioeconomics: Mr N. Prescott, WHOrs temporary adviser, who made an analysis of the documents so far available writes (see also Annex 2): "The proposed control programre will bring benefits both to the participating countries and to the countries threatened by vector reinvasion on the western border of OCP. These benefits will be of three kinds: Aggregate health benefits; aggregate income benefits, resulting from an increase in the quantity and quality of labour and land resources; and d-istributional benefits reflecting the fact that the Progranmers beneficiaries are among the worldts poorest. A framework for analysing these benefits is given in Annex 2. In the following section and in Ehe Annex 2, insufficient information is presently available to provide a basis for evaluating, even crudely, the size of the potential benefits of the proposed prograrrme, and no attempt will be made to do so here. Reco'nmendations for collection and analysis of relevant data are included. The only information available for each of the three participating countries relates to the prograluners possible impac! on the development of land resources. Eastern Senegal A list of four development projects, including two settlement schemes, planned for implementation in areas of known onchocerciasis transmission. The exEent to which the viability of these projects is endangered is not known. Western MaIi A list of agricultural and oEher development projects planned or in progress in the programme area. The extent to which onchocerciasis mPY affect the productivity of any of these investmenEs is not knom. Guinea The relative unoccupation of some of the river valleys in Upper Guinea has been attributed to the presence of the disease vector. The size and potential productivity of this underuEilized area is not knoum." 3. STRATEGY AND TACTICS TO BE APPLIED IN THIS PROGRAMME J 1 General strategy Despite its isolation, this Prograrrne will have to adapt the strategy on which the OCP is based (Le Berre et al. , L978, p. 72)z "The extent of flight of the female vector makes it necessary to treat fairly large areas". In the present situation, the northern and eastern limits being known (see above), the first objective is to determine the other Iimits in Senegal, Guinea, Guinea-Bissau, possibly the Gambia (no onchocerciasis focus is presently known in this country) and Sierra Leone (northern region), in order to cover the entire distribution area of the savannah cytospecies of S. damnosum. Three counEries (Guinea, Mali, Senegal) have already agreed, at the highest level, on the principle of joint acEion. "The longevity of the parasite in man (15 to 20 years) and the lack of therapeutic means of control make it necessary to pursue an entomological control campaign over a very long period". wcf ta.s page 5 Two questions can be raised about those principles being applied to this new area, viz is described as "isolaEed", why not. aim at the "eradication" of considerably reduce the period of treatmenE and definitely solve (i) Since the area the fly which would the problem? Unfortunately, it is not realistic to exPect that all S. damnosum savannah cytospecies foci in this difficult area could be discovered and correctly treated during the first phase of the campaign. Thus, those who will be in charge of this proSrame will have to have at Eheir disposal the means of facing any difficult control situation during a sufficiently long period. (ii) What will happen after 15 or 20 years? This question, already raised after the first four-year period of the ocP, can be answered this way: The isolation of this area and its contiguity with the ocP will certainly lead to an extreme reduction of the parasite in the human population as well as suppress Ehe problem of circulation of parasiEes due to fly migration between the treated areas of the ocP and the western zones under consideration. 3.2 Relations with the OCP Despite its contiguiEy with the OCP, this programne cannot, for simple logistic reasons' be envisaged as an extension of this first project: - The oCP has already, with the southern extensions implemented or planned in Ivory Coast, Ghana, fogo, Benin, reached its maximum possible size as far as circulation of data, technical and adminisErative instructions, Personnel, etc., is concerned' - The OCP has already reached its maintenance phase, the phase III area having been treated for two Years. However, iE can be expected thaE the experience gained in the OCP will be transferred to the new prograrme (Eraining already underway, new methods and techniques, expertise of different kinds, exchange of data, eEc.). 3.3 Tactics The structures of the OCP, the methods and techniques used in this progranrne could be adapted to the new areas as they have proven to be valid, especially as concerns: - Direction and technical units; - iulethods of treatment (aerial applications); - Insecticide selection and efficacy; - Methods and structures of evaluation; - Entomology: Sectors, sub-sectors, radio-cormnunications, etc. ; - Epidemiology: Simple and detailed evaluation; - Hydrobiology. 4, PI,AN OF ACTION The following plan is envisaged: assistance mission Eo the goverrunenEs will be organized with the following4.1 A preparatory terms of reference: wcf ta.s page 6 (i) Collection of existing data in the different fields of activities: - Entomology; - Epidemiology;(for these two disciplines, data collection already well advanced) - Socioeconomics; - Hydrology. (ii) Analysis of Ehese data. From the socioeconomic viewpoint, this analysis will concern existing and planned development programmes with their actual relation with onchocerciasis (see Annex 2). (iii) Initiation or completion of actions in the following fields of activiEy: ( a) Entomology: - Exact delimitation of the prograrrne boundaries in the west, south-west, south (distribution areas of cytospecies); - Aerial surveys of unknor,m areas for locating the breeding-places of the vectors at the different seasons; - Estimation of the transmission dynamics in Ehe more possible points. (b) EpidemiologY: - Assessment of the levels of endemicity and of the severity of the disease in selected villages; - Delimitation of the prograrrners boundaries in the west, south-west and south (see entomologY). ( c) HydrologY: - Planification for improvement of the number of the stations and the quality of the data. ( d) Hydrobiology: - Collection of basic data in the different basins; - Selection of the monitoring points. ( e, I rarnlnS: - Organization of training in the differenE fields. (iv) Planification of the control campaign, including a preliminary period of seLtlement and completion of studies. 4.2 The duration of this PAG Mission is estimated at two-and-a-half years. The cost per year is estimated (see Annex 1) at: - lst year US$ 49O OOO - 2nd year US$ 363 7OO - 3rd year US$ 17O 3OO Total ,r$ ,. OrO O* wcf ta.s page 7 4.3 The structures of Ehis PAGmission can be envisaged as follows Personne 1: A team comprising - A project leader; - An administrator;(1 medical officer and I operation officer are already composing the WIIO international staff) - Staff ( c lerks , drivers, etc. ) ; - National teams, working under national status, in order to collect further data (1 team in each country)i - Consultants. Equipment 5 cars; Provision for flying time; Provision for medical and entomological equipment. Maintenance: - Travel for staff and headquarters and Regional Office experts. 4.4 The best site for the headquarEers of this PAG mission would appear to be Bamako from where liaison inside and outside the prograrnne (including the OCP, the OCCGE/ORSTOM training centre, etc.) appears to be the best. 1vBcf 78.5 Page 8 ANNEX 1 TOTAL 1 Rent Government. BUDGET FOR THE PAG MISSION PERSONNEL - 1 project leader (entomologist) - 1 administrator - LocaI staff (clerk, EyPist, driver) - Consultants: (n/months x $ 45OO) - Entomology - Epidemiology - Socioeconomics - Hydrology - Ilydrobiology DUTY TRAVEL - Inter-country - Visits outside or from outside TRAINING (UltoP to be contacted) AERIAL SURVEYS ($ 4OO per hour) SUPPLIES 1 - Cars 3 smal1 cars (504 type) 2 four-wheel drive (L. Rover tYPb 3 VW camping-cars - Lab. + field equipment (including maps) - Office (equipment) MAIMENANCE - Cars (8 x 25 @O km x O.25) - Office - Lab. + field equipment REPORTS 8. PROGRAMME SUPPORT COSTS + L4"L 2 J 4 5 6 7 Year 2 t-tf zYear ToEa IYear 1 50 000 44 000 10 000 3 m/months US$ I 4 6 2 tl 2 uy'nonths US$ 25 000 22 000 5 000 il il ll I J 1 31 500 4 000 5 000 7 500 27 500 2 700 8 200 11 000 125 000 Ilo 000 25 000 166 500 25 000 37 500 lo4 000 23 LOO 24 200 24 800 t3 200 5 500 137 s00 13 700 4L 2@ 22 000 US$ 67 500 40 000 55 000 5 500 16 500 5 500 10 000 15 000 4 m/nonths US$ 67 500 60 000 ll il il 4 4 1 2 50 000 44 000 10 000 10 000 15 000 23 100 24 200 24 800 13 200 5 500 55 000 5 500 16 500 5 500 L49 400 20 900 898 200 125 800 429 8@ 60 200 319 000 44 700 1 024 000170 300490 000 363 700 of the premises, electricity, telephone, water, watchman to be paid by the il wcf ta.s page 9 ANMX 2 ECONOMIC APPRAISAL OF THE ONCHOCERCIASIS COMROL PROGRAMME IN THE SENEGAL RIVER BASIN AREA by Nicholas M. Prescott Magdalen College University of Oxford Eng land WIIO ConsulEant 1. INIRODUCTION This Annex first sets out the basic framework for economic appraisal of the control programne. It then makes recormrendaEions concerning the collection and analysis of relevant data. 2. THE FRA}IEWORK The purpose of the economic appraisal is to evaluate Ehe contribution made by the control progranme to the major objectives of the participating countries. The basic approach is to estimate and compare the time stream of benefits and costs occurring in future Periods that are associated with implementation of the project. 2.L The benefits The proposed prograrrne will yield benefits not only internal to, but also external to, the progrartrne area. The latter benefits will result from the reduced risk of continued transmission of onchocerciasis in some 1O% of the OCP area due to vector reinvasion from its western border. These benefits will be of three main kinds; aggregate health benefits, aggregate income benefits and disEributional benefits. The size of these benefits will depend fundamentally on the prevalence and severity of onchocerciasis which would occur in future periods without the control prograrrne, the extent of the reduction in prevalence and severity through time which will occur with the programne, and the speed with which chis reduction in morbidity occurs. 2.1.1 Aggregate health benefits These represent the future reduction in morbidity of varying degrees of clinical severity occurring in individuals of all age-groups as a resulE of onchocerciasis. These benefits may be expressed broadly in terms of the reduction in the number of people suffering blindness, visual impairment or infection without ocular involvement in each future year as a result of the control programne. These benefits contribute governmen! objectives to improve health status and are valuable independently of the programmefs contribution Eo other objectives. Their value will depend on the relative priority given to health improvement in each of the participating countries and may differ between Ehem. 2.1.2 Aggregate income benefits These will be of two types, refLecting the effect of the Programme on future availability of productive factors in the participating counEries: those resulEing from an increase in the effective supply of labour resources, and those due to an increase in the effective supply of land resources. (a) The effecEive increa se in labour supply. This benefit arises from vBcf 78.5 Page 10 Annex 2 (i) the future increase in the quantity of labour resulting from the reduction in complete disablement due to onchocercal blindness in working individuals; and (ii) the future i-ncrease in the quality of labour due to improved working efficiency resulting from the reduction in visual impairment or infection without ocular involvement in working individuals. This benefit may be expressed in terms of the reduction in the number of workers suffering blindness, visual impairment or debilitation withouE ocular involvement in each future year. Its value will depend partly on the marginal product of labour, and on the unknown but varying extent to which visual impairment or infection without ocular involvement impairs working effieiency. It is worth emphasizing that the benefits due to increased labour supply simply reflect the proportion of aggregate health benefits occurring in lndividuals of working age, and that the estimntion of both classes of benefit rests on a cormon epidemiological basis. (b) The effective increase in supply of land. This benefit rePresents the value of ,,ti1izingpot.'.ti.@dwhosedevelopmentiScontainedbythethreatof onchocerciasis posed by the presence of the disease vector in the areas concerned. The nature of this constraint may be of three kinds. It may be an absolute constrainE, such that local populaEions refuse to settle in the affected breas for fear of onchocerciasis, perhaps because of historical experience with settlement and eventual abandonment. Or it may be a relati-ve constraint, when the presence of the vector is not sufficient to deter seErlement initially but threaEens its long run viability with the potentia-l development of hyperendemic onchocerciasis. In other circumstances the vectorrs presence in unpopulated areas may be only one of several obstacles, aIl of which would have to be overcome Eo ensure successful exploitation of the land; examples of such constraints include lack of infrastructure (roads, schools and health services), flooding of river va1leys, and the presence of other disease vectors, notably of trypanosomiasis and schistosomiasis. The important point to recognize is that control of the onchocerciasis vector will rarely be a sufficient condition of viable settlement of new land, alEhough it may be one of several necessary conditions. The potential outPut benefits of new land use are likely to depend not only on their basic agroeconomic potenEial, but also on the extent to which vector control is integrated into a more general programle of rural developmenE involving additional costs, particularly of investment in essential infrastructure. They will also depend significantly on the rate at which the potentially available land will be developed. 2.t.3 Distributiona 1 bene f its These reflect the welfare premium attached to the health and income benefits accruing to the rural poor who will be the direct beneficiaries of the control prograurne. Two of the participating countries, Mali and Guinea, are among the twenty poorest countries in the worId, with per capita incomes of USg 10O and $ 15O respectivefy (1976). Senegalrs per. capita i.,come is higher, about $ 39O (L976), but average income in Ehe EasLern region is only half the country average. The beneficiaries of the programle are at the centre of contemporary concern with meeting the basic needs of the r';orldts poor. 2.2 The costs The costs of the control programne represent the value of the resources used by the progragme in each year during its operation. The bulk of these costs will be accounted for by foreign exchange inputs vBcf 78.5 Page 1l Annex 2 3. RECOMMENDATIONS An economic appraisal component of the feasibility study mission should be formed to evaluate the benefits and costs expected to occur during each year of the control PrograflEne. The component will be ted by a development economist and assisted by consultants in agronomy, human geography, sociology and agricultural economics. He will work in close cooPeration with the epidemiological and entomological survey comPonents of the missi-on. 3.1 Evaluation of benefits 3.1.1 Aggregate health be Baseline epidemiological data in the progrartrne area should be used to project the number of age-and sex-specific cases of morbidity of different degrees of severity that will be averted during each year of the control programne. This will require projection of: (i) the number of cases of onchocerciasis that would have occurred in each future year without the control prograrune, distributed by age-, sex and class of clinical severit.y; and (ii) the number of cases of onchocerciasis, distribuEed by the same categories, that will occur in each future year with the control progranme. 3.1.2 Aggregate income benef!ts Increase in the effective supplv of labour Data should be collected on age-and sex-specific parEicipation rates in the progranme area. These should be used in conjunction with the projection of age-and sex-specific aggregate health benefits to project the expected increase in Ehe quantity and quality of labour resulting from the control programe in each fuEure year. An attetrpE should be made to evaluate the extent of the impairment of working efficiency resulting from non-disabling onchocerciasis of varying degrees of clinical severiEy in order to provide a realistic basis for estimating the increase in the quality of labour due to the control prograrrne. Data should be collected on the level and likely rate of growth of the narginal product of uninfected labour in the relevant parts of the progranme area in order to estimate the probable increase in output generated by the projected increase in effective labour supply due to onchocerciasis control. Increase in the effective supply of land Detailed maps of population densiEy, land use and soil-agroeconomic characteristics in the prograflme area should be prepared and analysed in order to assess the quantity and quality of unutilized land which may be made available for development by onchocerciasis contro 1. Analysis of onchocerciasis transmission potential on the basis of annual biting rates in the unutilized areas should be undertaken in order to evaluate wheEher and Eo what exEent onchocerciasis is likeIy to represent a serious constraint on the developmenE potential of those areas. Analysis should be undertaken of constraints other than onchocerciasis which may hinder the development of areas in which onchocerciasis is idenrified as one possible constraint. Other consErainEs include lack of infrastructure (road, education and health services), transmission of other diseases, notably trypanosomiasis and schistosomiasis, flooding of river valleys and problems associated with the allocation of land tenure rights. vBcf 78.s Page 12 Annex 2 Detailed evaluation should be undertaken, in close cooperation with the relevant planning agencies in the participating countries, of the value of output generated in each future year by the development of land whose successful exploitation can be reaIisEically expecEed to be wholly or partly dependent on effective vector control, net of the cost of complementary resources used to overcome constraints additional to onchocerciasis. 3. 1. 3 Dis Eributional benefits estimated manpower requirements are: development economist (team leader) : agronomist: human geographer: agricultural economist : sociologist: An attempt shoulo be made, in tight of stated government objectives and observed policies in each of the participating countries, Eo assess the relative interregional and interpersonal distributional weight attached to the aggregate health and income benefits which will accrue to the beneficiaries of the control prograrmne. 3.2 Evaluation of costs Detailed evaluation of the expected costs of the control Progralrne occurring in each future year should be undertaken when the plan of operations is completed. 3 3 Resources required The economic appraisal team will undertake the collection and analysis of the necessary data during the second year of the feasibility sEudy phase, after the preliminary epidemiological and entomological surveys have been completed. The -1 -1 -1 -1 -1 5 man 2 man 2 man 2 man 2 man monEhs months months months months vBcf 78.s Page 13 MAP 1 THE SENEGAL RIVER BASIN AREA 5 l! )! a F J o cc UJ E o o ) F ,o () or_( : ,...} { -'\ h'/ - C 1 o d e I t o :u' l:r." a I a;rt L- - z ; I o ---a ) o E 1r I I t: , a J# I z f C o G i a, o .J1 -r rr., 1'. -i. ?llI tb.:- I !t ul I ,!)- \:. \ - ,a o 16I o I I I o UJI ot a o l a 2 lrJ =l o \i t\o I , o a E- eIiE -a9oE-E ;E2 40= <oJ iti t .ri I \ z ! 1r :i ; = (J i i, 1,,' o c C 0 I cc J o tr, 5S /I / I I l. t\ u / I vBcf 78.5 Page 14 ) i\ ( E(i z ) ) t I \ fl':; .-r- , d '.1 z g (J 9 2 JE t,\ ,l J G 92I I [q o \---r------ z ,^i 2 --;...rt \ev-t a E? z , f r,! E. q O ci LU t F -L = F :)(, l-z o(J LrJ =F oZ = -U) N L o )I <\\ lI l-_=" t l I I t \ 2 0 ) \+ n.r. .---\ ,l-'r 9 _r-. t o E -E .4t= ) t , _-l --. ^t I )\-.\{ , I\( t - \,tj'- ,.:f I ao o c J -\ i. -. :l:{ c:\ ;L tt -.\ I \ q. !-\a". IE*-{6,/.,' lvl\.\ - .,1 '?( \-r ittt ' ltl t .l J (, @ z TEis cc cEJ< <z oa; :s IJJ ./t -4.t'ul/-rj" TI I I I I I e G It t E I ( , € 0 )l .!1 '/ =z E I ; _at no -o i" t zo) =fo/ EE 6r -'L x \-r E I I I I I I i la, ?42 :)r @0 6-, U\ u r-Z2 =ioo \\ Jc \(- I _\- t J