Onchocerciasis control in Guinea-Bissau: achievements and Prospects after OCP

ONCHOCERCIASIS CONTROL IN GUINEA-BISSAU Achievements and Prospects after OCP 2002 I INTRODUCTION Onchocerciasis in West Africa before OCP . Onchocerciasis prevails in Africa, America and in the Arabian peninsula. . It was estimated that in the world: Approximately 122,9 million people were 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, C6te 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 I 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 rvorm) known as Onchocerca volvulus. The adult worm 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 govemments and WHO defined the limits, the objectives, the of consultative structures and management of the Prograrnme as well as the modalities for control operations and evaluation procedures. After approval of the missiou report of the "support Programme to Governlrlellts" itl January 1974, the budget necessary for the implementation of the oncliocerciasis control programme in tlie Volta basin rvas voted. \\rHO was then designated as the Executing Agency. In a fit of international solidanly, 22 countries and institutions financed the activities of OCP for nearly three decades. 1.1 I I I 2 n 1.2. Control Strateeies used The main strategy used is vector control to which ivermectin treatment was added in 1987. In certain areas, vector control was the method used and in others ivermectin treatment only. In some others on the other hand, the two strategies were combined. 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. 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 17 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 GUINEA-BISSAU BEFORE OCP In 1958, two very significant points of onchocerciasis were found at the border with the Republic of Senegal, close to Kolda and Kedougou. Other cases were also confirmed on the frontier area with the Republic of Guinea Conakry, on the basin of the Rio Corubal, in the villages of Cabuca and Fulamory. The first cases of onchocerciasis described in Guinea Bissau date back to 1965 in the villages around the town of Sonaco. The Onchocerciasis Control Programme began its activities in Guinea-Bissau in1989 Epiderliological prevalence levels varied from 0 to 73 o/o on the Rio Corubal basin and 0 to 30 %o on the Rio Geba. The Cornmunity Microfilarial Load (CMFL) reached 30 on the Rio Corubal, as against 4 microfilaria per biopsy on the Rio Geba. The rates of blindness went fronr 0 to 3 oh on the Rio Corubal, and from 0 to 5 % on Rio Geba. On the entomological level, the Annr.ral Transmission Potential (ATP) rvas 36 and the Annual Biting Rate (ABR) ri'as 1.210. J III. CONTROL STRATEGIES 3.1. Treatment with Ivermectin It is the only control strategy used in the Programme in Guinea Bissau. Ivermectin was introduced for mass treatment in 1990, but distribution was derailed by the social and political disturbances that year. Currently the training of the various actors will make it possible for the distribution of ivermectin to resume (through the Community Directed Treatment with Ivermectin or CDTI). 3.2. Training To ensure the maintenance of control gains by the Participating Countries, OCP undertook the training of nationals, as well in the academic domain, as on-the-job, especially in control strategies. 3.3. Other strategies Information, Education and Communication (IEC), epidemiological and entomological monitoring also constitute strategies for the control of the disease IV. 2OO2 RESULTS IN GUINEA-BISSAU 4.1. - On the loeical level The epidemiological evaluation carried out in June 2001 made it possible to visit 37 villages, that is to say twelve (12) in the Rio Geba area and twenty-five (25) in the Rio Corubal area, and gave the following results: The prevalence rate, the CMFL and the rate of blindness are nil in almost the entire evaluated villages. It should be noted that the rare positive cases were found in villages of the Rio Corubal basin (Gabu area). - On the entomolosical level From June to September 2001, 1 120 blackflies were caught. All of them were of the savannah species. The total number of flies witli L3 in the head rvas 41. All the flies with L3 in the head rvere found ir.r the basin of the Rio Corubal, at the Cabuca catching point. 4 aV. OBSERVATION Strensths: Results are satisfactory: decrease in the prevalence, incidence and CMFL. The staff were trained to undertake oncho control activities (epidemiological and entomological evaluation). Weaknesses: CDTI could not be implemented due to insufficient financial and material resources. Guinea-Bissau is yet to order ivermectin directly from MDP. VI. CONDITIONS TO SUSTAIN AND IMPROVE ACHIEVEMENTS Have sufficient ivermectin supply for the implementation of CDTI. Have a I00% geographic coverage. Reach 85% therapeutic coverage. Make a census of the population to be treated. Locate and treat absentees. Have the necessary means to undertake activities. Continue IEC activities at the community level. Undertake epidemiological and entomological activities at regular intervals -5