REPORT of OCP ACTIVITIES and the ENTOMOLOGICAL RESULTS in the OUEME Basrn (1978-2001)

1 WORLD HEALTH ORGANIZATION ORGANISATION TVIONDIALE DE LA SANTE AFRICAN REGION 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, Burkrna Faso Télégr . ONCHO OUAGADOUGOU Tél : 34 29 53 - 34 29 59 - 3429 60 Télex. ONCHO 5241 BF Fax' 34 2875 Original. English REPORT OF OCP ACTIVITIES AND THE ENTOMOLOGICAL RESULTS IN THE OUEME BASrN (1978-2001) By Samuel A. SOWAH* and Hyacinthe AGOUA* Under contractual service agreement with WHO/OCP The first version of this report was written by Mr S.A. Sowah for the period 1978-1998. The document was reviewed and updated by Dr. Hyacinthe AGOUA until2001, with the collaboration of the Programme Director and the Chiefs of Units. N" 123|02NCUTEC/3.9 *Medical Entomologists. Previously WHO-Oncho control Programme staff members Ouagadougou, June 2002 30-07 -02 2 CONTENTS I. INTRODUCTION 2. OVERVIEW OF THE ONCHOCERCIASIS CONTROL PROGRAMME IN WEST AFRICA -) DESCRIPTION OF THE OUEME BASIN AREA 4 ENTOMOLOGICAL ACTIVITIES (EVALUATION AND VECTOR CONTROL) 4.1. Entomologicalsurveillance. 4.1.1. Breeding sites. 4.1.2. Catching points. 4.1.3. Entomological prospections. 4.2. History on larviciding. 4.2.1. Aerial larviciding. 4.2.2. Ground larviciding. 4.2.3. Insecticides used (Insecticides rotation) 4.3. Entomological results. 4.3.1 Vectors concerned. 4.3.2 Parasites concerned. 4.3.3 Transmission. 4.3.4 Special studies on S. soubrense Beffa form. 4.3.5 Entomological results on 3 1 -12-2001. 5. SURVEILLANCE OF AQUATIC FAUNA 6. EPIDEMIOLOGICAL EVALUATIONS 6.1. Epidemiological results before vector control. 6.2. Epidemiological results during vector control. 6.3. Latestepidemiologicalresults. 6.4. Recent ophthalmological evaluation. 7 IVERMECTIN DISTRIBUTION. 8 SOCIOLOGICAL INVESTIGATIONS. 9. POPULATIONS SENSITIZATION AND MOBILIZATION ACTIVITIES 10. DISCUSSIONS. I1. CONCLUSION 3 1. INTRODUCTION This report is written as a result of contractual service agreement entered into by OCP with the authors. The aim of this report is to give a consolidated account of OCP activities in the Oueme river basin as well as the results obtained from the beginning of OCP activities to date. 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 clistribution. sociological investigations if any, sensitisation carried out by OCP field staff. and any other relevant inforrnation available. 2. OVERVIBW 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, Côte 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 tlre Programme activities in Côte d'Ivoire in 1978-lg7g, the Programme area covered 764,000km2, which represents about 18,000 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, Côte d'Ivoire, Ghana, Guinea, Guinea-Bisau. Mali. Niger, Senegal, Sierra Leone and Togo) and covers 1,300,000 t<m'z 1fig. t;. The Prograrnme 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 ls 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 (Eastem 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 Bandiagata, 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 (LINDP) and the World Bank. 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 3l December 2002. 4 3. DESCRIPTION OF THE OUEME BASIN AREA The entire Oueme basin lies in the Republic of Benin. It stretches from latitude 10 degree North and enters into the Gulf of Benin at the coast of the Republic of Benin (fig. l), in a woody Savannah area known as the Dahomey Gap, where the Savannah type of vegetation stretches from the North of Benin right to the coast. There are two types of climatic conditions, giving two types of seasons, namely the rainy season and the dry season. The rainy season starts in the South around late March and in the North between mid May to mid June. The rainy season ends around rnid or end of October. This ushers in the Harmattan, which marks the beginning of the dry season. The principal tributaries of the Oueme are: the Alpouro, the Yerou Maro, the Wewe and the Terou in the North. In the middle portion are the Odola, the Beffa, and the Adjiro. In the South are the Okpara and the Zou. Hydrolog.v Generally, the main river and its tributaries flow mainly in the rainy season, namely from late .lune to the middle of October, with the peak around the month of September. From late October to the middle of November most of the tributaries stop flowing. The main river, however, continues to flow up to the middle of January. The discharge of the Oueme can be more than 1000 cubic metres per second. This was recorded in week 36 in 1998 at Atchakpa(frg.2). On the tributaries the discharge can be around 500 cubic metres per second. This was recorded at Atcherigbe on the Zou in 1999 in week 35 (fig. a). In the dry season, the entire basin dries up with no flow at all from the North to the area around Zagnanado where minor flow can be observed. Eventually these flows also stop a month or two before the onset of the rainy season. The Oueme river and its tributaries are devided into several stretches, according to the -OU irnportance of the tributaries and the discharge, 100, OU 400...etc. (fig. 8). 4. ENTOMOLOGTCAL ACTTVTTTES (EVALUATTON AND VECTOR CONTROL) 4.1 Entomological surveillance 4.1.1. Breedins points . ln order to make the work easer for the Aerial Operations team, nver sfrefches are coded by taking into account, the name of the river basin and adding a number from 100 to 900. For example : OU 100 and OU 400 means: Oueme nver, stretches : 100 and 400. 5 Oueme The S. damnosum s.l. breeding points on the Oueme itself begins from lat. 9 degrees 40 minutes north, a little bit downstream from Affon catching point. From this breeding point to the confluence of the Yerou Maro, six other important breeding points can be found (fig. 6). Eleven other major breeding points are found from Beterou (lat. 9 degrees 13 minutes North) to the confluence of the Odola (lat. 8 degrees 46 minutes north). Note that these points are identified only in latitudes because of the fact that the Oueme flows virtually from North to South, hence, the latitudes pinpoint to a particular point on the river. From the confluence of the Odola to the Atchakpa breeding point, eleven other major breeding points can be identified. The main complex breeding points on the Oueme are found between Atchakpa catching point and Aguigadji catching point. At this stretch (from lat. 8 degrees north to lat. 7 degrees 29 minutes north), the breeding points are virtually joined together with very few pools in-between. Below the Atchakpa-Aguigadji stretch apart from the complex breeding point at Tamiedji (lat. 7 degrees 25 minutes north). there are, practically, no natural breeding points. On the other hand occasionally man made fish traps can be found here and there (fig. 6). Alpouro Very few breeding points are found on the Alpouro, which are not important for S.damnosum s.l. breeding. Yerou Maro On the Yerou Maro also very few S. damnosum s.l. breeding points are found. The only important breeding point is found near its confluence with the Oueme. Wewe The breeding points on the Wewe are not many and are not important for S. damnosum s.l breeding. Terou There are very few breeding points on the upper stretches of the Terou, where the river flows from North to South. The important breeding sites are located frorn the confluence of the Aguimo to the confluence of the Terou with the Oueme. Odola One important breeding point on the Odola is situated near its confluence with the Oueme. Other minor breeding points are found upstream but these do not play important role in S. damnosum s.l breeding because of the short duration of flow of this tributary.

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