Onchocerciasis control in Guinea: achievements and prospects after OCP

ONCHOCERCIASIS CONTROL IN GUINEA Achievements and Prospects after OCP 2002 1 II. Ir ? 1.1. Onclroc. Africa be Onchocercia:; ,;revails in Africa, America and in the Arabian peninsula. It was estimated that in the world: Approximately 122,9 million people are exposed to onchocerciasis. More than 17,7 million people were infected with the disease. More than 270 000 people were blind and at least 500,000 had visual impairment cased by onchocerciasis. Africa is the continent most affected, with more than 16.9 million (95%) victims. West Africa was not only particularly affected but most of all it had the most significant foci of the most serious form of the disease. These foci were located particularly in the northern parts of Benin, Togo, C0te d'Ivoire, Ghana, east of Mali, the south of Niger and were disseminated in the whole of Burkina Faso. It is in these areas known as the original area, covering 654,000km2 that the Onchocerciasis Control Programme in West Africa (OCP) was started. The Programme then extended to the foci south of C6te d'Ivoire, Benin, Togo and Ghana, then to the west of Mali, Guinea, Guinea-Bissau, Senegal and Sierra Leone. Today, the whole of the Programme area covers 1 235 000 km2 with almost 40 million people. Before the beginning of the control operations, there existed more than 3 million onchocercal patients out of which approximately 135,000 were blind. Onchocerciasis is a parasitic disease. It is caused by a filarial (a worm) known as Onchocerca volvulus. The adult wonn which develops only in man produces microfilariae which is transmitted to other men by the bite of a tiny fly commonly called "simulie", the vector of the disease. Onchocerciasis prevails only in rural areas, in the settlements located along the rivers with fast flowing current. The simulie reproduces in these rivers, hence the name "river blindness" which is still interchanged with the name onchocerciasis. The most exposed communities are those located approximately ten kilometres on both sides of the rivers. Blindness, the nuissance and other consequences of onchocerciasis are factors for the deterioration of the living conditions of these communities and the cause of the abandonment of the fertile riverain lands by the villagers. An agreement signed in 1973 between the participating governments and WHo defined the limits, the objectives, the of consultative structures and management of the Programme as rvell as the modalities for control operations and evaluation procedures. After approval of the mission report of the "support Programme to Governments" in January 1974, the budget necessary for the implementation of the onchocerciasis control prograrnme in the Volta basin was voted. WHO was then designated as the Executing Agency. In a fit of international solidaity, 22 countries and institutions financed the activities of OCP for nearly three decades. I 2 a 1.2. Control Strateeies used The rnain strategy used is vector control to which ivermectin tre. In certain areas, vector control was the method used and in others iverr, some others on the other hand, the two strategies were combined. { )a9% 1.3. Results obtained in the OCP area Onchocerciasis is now eliminated as a problem of public health in all the OCP area. In some limited foci however, there is the need to improve on the results achieved. r Nearly 40 million people are protected today from onchocerciasis and more than 18 million children born since the beginning of the Programme have escaped the risk of onchocercal blindness. 600,000 cases ofblindness have been prevented Presently, more than 25 million hectares of riverain lands have been redeemed and is being re-populated and developed. This will enable about l7 million people to be nourished. It is to be noted however that, at some points, the results need to be improved. These are the tributaries of the Oti in Togo, the Ou6m6 in Benin, the Pru in Ghana, the Mafou and the Tinkisso in Guinea. II. ONCHOCERCIASIS IN THE REPUBLIC OF GUINEA BEFORE OCP The republic of Guinea is considered as the water reservoir of West Africa, and is also a vast onchocerciasis territory. The disease covers about 218,000 sq km (about 85% of the total area. At the outset of control, more than 2 million Guineans were directly exposed to the disease, with 560,000 of them being carriers of microfilariae and 20,000 blind. The prevalence of the disease was over 80% in some villages, and the Community Microfilarial Load was 45o/o, with a blindness rate of about 10%. The Annual Transmission Potential (ATP) was between 0 and 2075, while the Annual Biting Rate/man (ABR) varied between 1290 and25,767. III. CONTROL STRATEGIES The Onchocerciasis Control Programme is based on two main strategies: vector control (larviciding, used in rotation on watercourses), which was, and remains the main onchocerciasis control strategy. The programme had a second control strategy, when ivermectin (microfilaricide) came on board in 1987. J In Guinea, the combination of the two strategies (vector control and treatment with ivennectin) on the field actually started in 1989. The evaluation of vector control started by the establishment of an administrative and Eeclinical structure, made up of sectors and operational bases, charged with entomological surveillance in I I river basins. Beginning 1991, two sectors: Kankan and Faranah supervised the entomological evaluation activities of nine operational bases in eight river basins. Upon the cessation of larviciding in the basins of the upper Sassandra, Sankarani, Milo, Mongo Kaba and the Kolente, the operational bases of Beyla, Kerouane and Mamou were closed in December 2001. Currently, larviciding is carried out only on the basins of the Niandan, Upper Niger, Mafou and the Tinkisso. Treatment of the populations with ivermectin actually started beginning 1989, with mobile OCP/national teams. Treatment is now carried out by the communities themselves, through the Community-Directed Treatment with Ivermectin (CDTI) approach, thanks to village volunteers called community distributors (CDs). To ensure the maintenance of control gains by the Participating Countries, OCP undertook the training of nationals, as well in the academic domain, as onthe-job, especially in control strategies. Information, Education and Communication (IEC), the epidemiological and entomological rnonitoring also constitute strategies for control of the disease NGO support, such as that of OPC and SSI are critical for the post-OCP period IV. RESULTS IN 2OO2 Entomoloeical level The main indicator is the Annual Transmission Potential (ATP). As of 31 December 2001, this potential varied over the entire basins between, 0 and 56 infecting larvae/man/year, whereas the standard should be lower than 100. Epidemioloeical level The onchocerciasis prevalence, which was between 43Yo and 8802, prior to treatment, is now reduced to 10o/o, and even OYo in some cases, due to the combined strategy of vector control and ivermectin treatment. 4 Ivermectin treatment In2002,7320 villages were treated out of the planned 7478 (98% of geographical coverage), and out of 2,455,457 persons registered, 1,989,850 were treated(81% of therapeutic coverage) These results are relatively good, given the fact that the main CDTI objective is to have IO0% geographical coverage, and at least 65Yo of therapeutic coverage. Trainins On the whole, 350 doctors, nurses and heads of health centres, as well as 14,453 community distributors were trained in OCP control strategies. Besides, 16 prefecture epidemiological surveillance teams were identified and trained in the prefecture health directorates. Eighty-five Guineans benefited from OCP training scholarships, of which forty-one were in entomology, nine in epidemiology, five in parasitology, ten in hydrobiology, five in public health, three in ophthalmology, nine in health service management, etc. V. OBSERVATION Strengths Vector control, the basic strategy of onchocerciasis control, has enabled the transmission of the disease to be reduced in a remarkable way in the OCP area. At the present stage of control, the disease is no longer a public health concern, neither is it an obstacle to socio-economic development. There is a national decentralized health system, and a national will to ensure integration. CDTI, which is less onerous, has given rise to quite high geographical and therapeutic coverage rates. There is a qualified national staff on the field to continue control activities. Partnership exists between NGOs such as OPC, Sight Savers International and HKI. Weaknesses The services of community distributors are offered free of charge; this compromises the sustainability of the strategy, with the continuous claim for incentives by the distributors. Low level of involvement of local representatives in the CDTI process. VI. CONDITIONS TO SUSTAIN AND IMPROVE ACHIEVEMENTS AFTER 2OO2 Arrive a|100%o geographical coverage, and at least 65Yo therapeutic coverage in each village under CDTI, at each treatment session. In the southern part of Guinea, undertake a complete census, on a periodic basis, in the refugee camps to ensure management under CDTI. The prefecture epidemiological surveillance teams must have adequate equipment for detecting new onchocerciasis cases among the population. There must be required training for village catchers in entomological monitoring. 5 Continuation of the epidemiological and entomological surveillance. Ground treatment in the areas of socio-economic interest, has proved to be against blackfly nuisance on 12 points. Need to develop advocacy with new donors, for mobilizing needed resources for the maintenance and improvement of gains. Making available to the national onchocerciasis control programme a staff that is already trained on strategies. Need to renew and"/or beef up vehicle fleet, as well as field technical equipment (for skin snip test and catches/dissection) 6