Main lines of devolution activities related to onchocerciasis in the original OCP area and the southern extension in Côte d'Ivoire

WORLD HEALTH ORGANIZATION ORGANISATION MONDIALE DE LA SANTE ONCHOCERCIASIS CONTROL PROGRAMME IN WEST AFRICA PROGRAMME DE LUTrE CONTRE L'ONCHOCERCOSE EN AFRIQUE DE L'OUEST EXPERT ADVISORY COMMITTEE Thirteenth session Ouaeadoueou. 8-12 June 1992 ocP/EAcl3.8(oCP/DEVO/ng/W/92) MAIN LINES OF DEVOLUTION ACTIVITIES RELATED TO ONCHOCERCIASIS IN THE ORIGINAL OCP AREA AND THE SOUTHERN EXTENSION IN COTE D'IVOIRE AS/an WORLD HEALTH ORGANIZATION ONCHOCERCIASIS CONTROL PROGRAMME rN wEsr AFRTCA (ocP) Original: French REV. I IVIAIN LINES OF DEVOLUTION ACTTVITIES RET.AIED TO ONCHOCERCIASIS IN THE ORIGINAL OCP AREA AND THE SOTJTHERN E}MENSION IN COTE D'TVOIRE oCP/DEVO / n9/DOC|92 MARCH 1992 MAIN LINES OF DEVOLUTION ACTIVITIES REI.-ATED TO ONCHOCERCIASIS IN THE ORIGINAL OCP AREA AND THE SOUTHERN EXTENSION IN COTE D'IVOIRE 1. GENERAL CONSIDERATIONS The original Programme area and the southern extension in C6te d'lvoire cover an area of 764,000 square kilometres which stretch over Benin, Burkina Faso, C6te d'Ivoire, Ghana, Mali, Niger and Togo. It was in this part of the programme area that vector control, the only available means for the control of onchocerciasis, was started benreen 1975 and 1979, depending on the area (Annex 1.). Today, discussing devolution i.e. the taking over by the Participating Countries of the activities which wilt help maintain and strengthen OCP's achievements, it is normal to consider first the part of the Programme which has already benefitted from 12 to 15 years of larvicide spraying operations. It is there that OCP can progressively hand over to the beneficiary countries the full responsibility for carrying out the residual activities related to the control of the disease. It should be noted that, today transmission of the disease has been definitively interrupted in approximately 80Vo of the Programme area. In this area excellent epidemiological results have been recorded. The prevalence of onchocerciasis is less than SVo almosteverywhere and there is no risk of onchocercal blindness anyrhere. The advent of Mectizan in the Programme in 1988 has provided the beneficiary countries with an effective tool for the control of river blindness, which is clearly within their technical, financial and human resources and which should be easier for them to handle than the large-scale vector control. Armed with these achievements and the fact that the new drug makes it possible from now on to address the devolution process in real operational terms, OCP has stopped larvicide applications in70-80%o of its initial area. The blackflies are therefore returning, as foreseen initially. Today, the bites of these flies can, at best, only be a source of nuisance and not of onchocerciasis. In fact, the number of blackflies that carry the parasite responsible for river blindness is practically nil. It should, however be noted that up to 1989 the western and south-western fringes of the original Programme area in Mali and Cdte d'Ivoire had been invaded by blackflies coming mainly from Guinea and Sierra l*one. Although this reinvasion has been completely brought under control since 1990, the entomo-epidemiological results are not yet quite satisfactory in these areas which had been infested by the reinvading blackflies for too long. A similar reinvasion phenomenon prevails also in the south-eastern part of the original programme area, in Togo and Benin. The problem has been partly solved by the southern extension of the Programme but blackfly migration from Nigeria still persists. Furthermore, there is a small localized focus in Burkina Faso, Pendie focus, where the epidemiological trends, though satisfactory from the public health viewpoint, are out of phase with the rest of the country by about ten years (slower decrease in prevalence). This is due to the fact that a residual transmission which was not detected in time continued and even intensified between 1980 and 1985. It is noteworthy that even though the prevalence in this focus is still relatively high (around 8Vo) compared to those recorded in the rest of -2- the country, the risk of blindness is nil because of the large-scale distribution of Mectizan that has been going on there since 1988. In the southern extension area in C0te d'Ivoire and in certain localized zones in the original Programme area, problems were encountered with larviciding operations as a result of the exceptional complexity of certain breeding sites of the vector ai well as the resistance of some blackfly species to the insecticides, orginophosphorus compounds, that have so farbeen the easiest and the most effective insectiiiae io ur". Conr.quintly, while the entomo- epidemiological results in these zones are still acceptable from the iiandpoint of publichealth, they are not as satisfactory as those recorded in the greater part of the oiiginalProgramme area. Finally, it should be pointed out that there is an occurrence of considerable movements of migrants with onchocerciasis into certain river basins where transmission ofO. volvulus has been completely interrupted and where OCP has stopped vector control, asfor example in the Banifing IV basin in Mali. These migratory movements deserve thereforeto be monitored very closely and appropriate ,neairr"s in the form of treatment ofimmigrant patients need to be taken. fn fe light of the above, it is easy to understand that, during the fourth FinancialPhase (1992'1997), OCP will have to coniinue the larviciding operatiSns in 20 to 3OVo of its original area and in the whole of the southern extension in COte d'Ivoire. The vector control w_ill be strengthened where necessary, by the treatment of the population with Mectizan. However what will attract particular attention during this period, *iit U. the activities which the countries concerned will carry out themselves in the ireed zones as part of devolution as a proof of their determination to protect and strengthen OCP', u.hi.r.ments. These activities are defined in the devolution plans prepared by the seven countries in the originalProgramme area and which have alreaay trlen approved by the Joint prograilme Committee, the Programme's supreme decision-making body. Th.r. devolution pians lay emphasis on the pressing need to integrate onchocerciasis control into other ongoing health activities in the countries. For the specific case of onchocerciasis which directly concerns us here, the overall strategy for the control.or more appropriately for the maintenance and strengthening of ocP's achievements will be based on the above-mentioned basic data. 2. STRATECY FOR THE MATNTENANCE AND STRENGTHENING OF OCP'SACHIEVEMENTS IN THE ORIGINAL PROGRAMME AREA lt has been demonstrated that after 14 years of complete interruption of transmission of the onchocerciasis parasite, the risk of recrudescence of ihe disease becomes very low and even negligible. This period corresponds to the maximum life-span of the adult worm in man. The risk of recrudescence after the cessation of vector control operations depends, among other factors, on the existence of a residual parasite reservoir, the density ^of tn.biting female vecror and the immigration of infected individuals. -3- The Participating Countries should therefore be vigilant and, as part of the devolution, take steps aimed at preventing any serious recrudescence of onchocerciasis to prevent any intense and generalized resumption of transmission which may result in high rates of incidence of the disease and which may finally bring about new cases of onchocercal blindness. The strategy to be adopted for the attainment of this objective is based on four main principles lines : Informatiorl Education and Communication (I.E.C) ; epidemiological surveillance ; Mectizan treatment of migrant onchocerciasis-patients ; Mectizan treatment of populations found to be at risk of recrudescence of the disease. The implementation of this strategy would require an adequate training of staff at all levels. 2.L. Information. Education. Communication (I.E.C) Activities to raise awareness to be carried out through informatiorl education and communication with the authorities and the population are fundamental to devolution. First of all, the governments of the Participating Countries wilt have to be made aware of the importance of the maintenance of onchocerciasis control which should be included in their main public health priorities. Once the political will of the governments has been aroused, education and community mobilization efforts will have to be initiated since the control of the disease will be increasingly dependent on epidemiological surveillance and Mectizan treatment. Studies on the knowledge, attitudes and practices will enable the identification of gaps in the knowledge on onchocerciasis and the attitude towards the disease and the return of the blackfly after the cessation of larviciding. Such studies will enable the definitive identification of the appropriate means applicable for the dissemination of public health messages. 2.2. Epidemiological surveillance In the areas where larvicide sprayings have been carried out successfully for many years, an active epidemiological surveillance by mobile teams will be the most appropriate means for early detection of any possible recrudescence of infection. However, passive epidemiological surveillance by fixed health centres or by the rural communities themselves should not be neglected because it can also provide important epidemiological information (suspected onchocerciasis-patients, immigrant onchocerciasis-patients, etc.). Active epidemiological surveillance will consist of parasitological surveys based on skin snips in communities at high risk, living close to the vector's breeding sites. -4- Villages in which this epidemiological surveillance is carried out are called "surveillance" villages or "sentinel" villages. During these epidemiological surveillance surveys, particular attention should be paid to the presence of immigrants and to the identification of their places of origin. Besides, special studies on human migration should be organized on a larger scale to gather further information on this important phenomenon which can be an important factor in the resumption of transmission among the local populations in certain zones with high blackfly densities. 2.3. Mectizan treatment of infected immigrants All immigrants found to be positive by skin snip test or highly suspected to have onchocerciasis during epidemiological surveillance or special migration studies, should be treated with Mectizan. Of course, the presence of immigrant onchocerciasis-patients in an area is not synonymous with recrudescence of the disease but their treatment with Mectizan is undoubtedly a measure to prevent it. 2.4. Mectizan treatment of population found to be at risk of recrudescence If, after an active epidemiological surveillance, it is proved that there is recrudescence in an area, large-scale Mectizan treatment will be undertaken. At present, it is recommended to give this treatment once per year for a relatively long period (about 15 years). N.B.: The strategy defined above fully applies today to the freed zones in the original Programme area. On the contrary, in the southern extension in Cdte d'Ivoire and the zones in the original Programme area where entomo-epidemiological results are not yet quite satisfactory, epidemiological surveillance cannot be instituted at the moment for detection of recrudescence of the disease. Furthermore, in these zones, Mectizan rreatmenr should be seen as a complement to vector control with a view to controlling onchocerciasis more effectively. 53. EPIDEMIOLOGICAL SURVEILI-ANCE AND MECTIZAN TREATMENT ZONES IN THE ORIGINAL PROGRAMME AREA AND THE SOUTHERN EXTENSION IN COTE D'IVOIRE IN 1992 To facilitate the coordination of the actions of the different partners concerned with devolution activities in the field (Participating Countries, OCP, NGOs, etc.), it seems appropriate, after the account that has just been made on the overall strategy, to define clearly the zones which will be subjected to epidemiological surveillance and those eligible for Mectizan treatment in the original Programme area and southern extension in Cdte d'Ivoire. It goes without saylng that the information, education and communication activities will cover all the zones, with special emphasis on those where the risk of recrudescence is presumed to be greatest. Since larviciding is still being continued in 20-30Vo of the original Programme area and in the southern extension in COte d'Ivoire, it should be foreseen that changes would occur in the delimitation of zones as the insecticide sprayings come to an end. The zones presented below therefore relate to 1992 only. Annex 2 shows, among other things, the zones of the initial Programme area where preparations are being made towards the cessation of vector control operations. The collection of parasitological dat4 which wilt enable decision-making as regards the stopping of these larvicide treatments, is therefore necessary in this part of the OCP area. Consequently, for the moment, these zones will not be subjected to Mectizan treatment. 3.1. Epidemiolosical surveillance zones See Annex 2 for the location of the zones and Annex 3 for the entomo- epidemiological criteria for their delimitation. As can be observed, these zones in 1992 are mainly in Burkina Faso and Niger. Furthermore, it should be noted that the river basins in which this epidemiological surveillance will be undertaken are no longer subjected to larviciding operations. The epidemiological surveillance surveys in these zones come under the full responsibility of the Participating Countries concerned. OCP will, of course, continue to play its role of adviser and a catalyst. 3.2. Zones elisible for Mectizan treatment Annex 2 shows also the zones where it is justified to make large-scale Mectizan treatments. As shown in Annex 3, they are zones where the entomo-epidemiological results are not yet fully satisfactory. The general considerations presented earlier give the main reasons for these partially satisfactory results : reinvasion by blackflies from untreated areas, larviciding difficulties due to the complexity of certain breeding sites, resistance of the blackflies to the organophosphorus compounds, residual transmission that went unnoticed for a long time, relatively late start of larviciding and influx of infected immigrants. -6- With the exception of the Banifing IV basin in Mali, all the other basins concerned with this Mectizan treatment will continue to be treated with larvicides by OCp. As in the western and south-eastern extension areas, the onchocerciasis control strategy in these zones will therefore be based on vector control and Mectizan distribution under the direct responsibility of OCP during the fourth Financial Phase. However, the national teams of the Participating Countries will remain the main actors in the Mectizan treatment of the populations in these zones. As regards Mectizan treatment of infected immigrants in the Banifing IV basin, it will, with the technical support of the Programme, be the full responsibility of Mali since OCP has ceased larviciding in this basin after having completely attained its objectives there. 3.3. In all the other zones outside those mentioned above, the prevalence of onchocerciasis is negligible and likewise the possibility of its transmission. -Consequently, only passive epidemiological surveillance will be undertaken in the course of routine riedicai examinations at fixed health centres. As regards active surveillance, it will be conducted only exceptionally on the basis of an indication of new local infections revealed by passive surveillance. Mectizan treatment will be instituted for possible immigrants who are infected or when there is a confirmation of recrudescence. */.\ tU(o b a E = oo oOao I I / \ a o o UJ i,aaa t' I C) E o aa I JI. E l.'\ola ,a o \ t ? GDo(, foo t 3 oat a aaaoao I F. 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