Summary of the activities of the PET unit: briefing paper document for EAC 22, June 2001

SUMMARY OF THE ACTIVITIES OF THE PET UNIT Briefing Paper Document for EAC 22, J:u;rte 2001 This document gives an outline of the activities which were caried out in the PET Unit in 2000 and the first quarter of 2001 . 1. Epidemiological evaluations 1.1 In the original Programme area: Epidemiological evaluations were undertaken in more than 88 villages of the different river basins among which were the Alibori and M6krou basins in Benin, the Bougouriba, Como6, Leraba, Mouhoun (Black Volta), Sissili, Koulpeologo, Nakambe (White Volta), Nazinon (Red Volta) and Oti-Pendjari basins in Burkina Faso; the Bandama, Baoule, Comoe, Marahou6, N'Zi, Sassandra and Black Volta basins in C6te d'Ivoire; the Black Volta (Bui) basin in Ghana, the Diamangou, Niger and Sirba basins in Niger in the original Programme area where vector control was stopped more than 10 years ago. The results remain satisfactory and excellent in the majority of the basins under epidemiological surveillance with a prevalence around )oh in the majority of the villages. In the N'Zi basin in Cdte d'Ivoire, the incidence of infection of more than 1olo observed in two villages is being investigated by the national team. In certain basins of the original Programme area (Sissili in Ghana and Oti and its tributaries in Benin, Togo and Ghana), whose communities are under treatment with ivermectin, the unsatisfactory epidemiological results deserve regular monitoring and a special study of the situation. I.2 Epidemiological evaluations in the extension areas: More than242 villages were evaluated in the extension areas in Benin, Ghana, Guinea, Mali, Senegal and Togo in the basins under combined larviciding and ivermectin treatment or ivermectin distribution alone. In the basins where vector control will be stopped at the end of 200I, like the Sankarani, Dion, Milo and Kaba basins in Guinea; Amou, Anie, Asukawkaw I Dayi, Mono basins in Togo, and the tributaries of Lake Volta East (Dayi and Asukawkaw) in Ghana, the results are excellent on the whole with a good epidemiological trend. Evaluation of the epidemiological situation as well as specific studies are underway in all these basins. In the zones of the westem extension where the only control method is ivermectin treatment, some evaluations were carried out in the basins of the Bafing, Gambia, Bakoye and Koulountou in Guinea, Baoul6 and Falem6 in Mali, and Falem6, Gambia and Koila-Kabe in Senegal. The results are satisfactory in all these basins with more than 40o/o reduction of the prevalence rates of the infection which were 80o% in the worst villages before the large scale ivermectin distribution. Table 1 recapitulates these results. 1.3 Ophthalmological evaluations: For the purpose of studies of the long-term impact of vector control in the original Programme area, some ophthalmological evaluations were carried out in seven villages in Burkina Faso, three villages in C6te d'Ivoire and three villages in Ghana. The preliminary results show a total absence of microfilariae and ocular lesions in the majority of the villages but special attention must be given to the villages of Mouvielo in the basin of the Bougouriba in Burkina Faso and Kayoro in the basin of the Sissili in Ghana where new ocular lesions were detected. In the extension areas in the basins Niger and Milo in Guinea, Niger (Bamako) in Mali and Pru in Ghana, the ophthalmological evaluations showed that there are no more new evolutionary lesions except in the villages of Asubende on the Pru and Kayoro on the Sissili. A detailed analysis will be presented at the meeting. 2. Ivermectin treatment Community Directed Treatment with Ivermectin (CDTI) continued during 2000 and ended in six countries (Benin, Burkina Faso, Guinea, Mali, Senegal and Togo) out of ten at the end of December 2000 thus covering approximately 6.4 million people treated out of 8.3 million registered. Thus, more than 18,647 villages were covered in these six countries with an average village coverage rate of 97oh. The average therapeutic coverage of the population was77.3oh. Ghana began its treatment at the end of 2000 and during the first quarter of 2001 while a few treatments were carried out in C6te d'Ivoire during 2000. The training and treatment of the communities were carried out in the south of Sierra Leone thanks to tl-re financial support of OCP and the NGDO SSI. Some epidemiological evaluations have been planned in Guinea Bissau in order to decide on the advisability of a resumption of CDTI after more than three year 2suspension of ivermectin treatment in the basins of tlie Rio Geba and Rio Corubal for reasons ol insecurity. All the countries except Guinea Bissau and Niger ordered the Mectizan tablets necessary for their treatment themselves. Emphasis is now laid on the reinforcement of CDTI monitoring in the areas where the transmission remains unacceptable and on the possibility of stopping ivermectin treatnrent itl certain basins where the epidemiological situation is excellent. The results of the extemal evaluations of CDTI carried out in four countries (Benin, Ghana, Guinea and Mali) will be presented as well as the progress report of the 2001 treatments in the countries. 3. Diagnosis The rapid test for the detection of the IgG4 antibodies of Onclrccerca volvulus was caried ottt iu some selected villages in the areas where the transmission has been intemrpted like in Niger and in those areas where it has resumed such as in Burkina Faso, as well as in the endemic forest zone in COte d'Ivoire. The results of this test carried out in twelve villages of six countries will be discussed during the meeting. 4. Epidemiological modelling The integrated analysis of the entomological and epidemiological data of OCP was continued in collaboration with the department of public health of the Erasmus University of Rotterdam in order to improve the epidemiological predictions using the epidemiological model ONCHOSIM. The major chillenge remains the effective use of this model by the countries. The integrated analysis usin.o ONCHOSIM continues in order to study the real impact of long-term treatment with ivermectin on transmission. 5. Training and transfer of the data to the countries The countries expressed great interest in the process of transfer of the data to the peripheral level and the effective take over of onchocerciasis control activities by their own structures. Thus, the retraining of field personnel was reinforced during the epidemiological evaluations and the planning of these activities made with their collaboration. Nevertheless, efforts remain to be made at all levels. Tabte 1: Recapitulation of the epidemiological results of the villages evaluated by country between Fe 2000 and 2001 Range (min. - max) Preval. (7o) Max CmflIntervention Nb of villages Evaluated Countrv 0 4.73 0.04 (o - 0.6) (o - 46.6)(t.r - 2.1) Ivermectin Larviciding * Iverm. Surveillance 2 l3 2 Benin 0.95 0.08 6 20 (o - 17.3) (0 - 4.s)IvermectinSurveillance Burkina Faso (0.6 - 20.s) (0 - 8.8)(0 - 9.2\ 0.47 0.45 0.56 4 8 28 C6te d'Ivoire Ivermectin Larviciding + Iverm. Surveillance (1 - 18.8)(0 - e.e) L06 0.38 l3 2t Ghana Ivermectin Larviciding + Iverm. (0 - 2r.l) (o - 19.3) 1.07 I 39 84 Guinea Ivermectin Larviciding + Iverm. (0 - 13.5) 0.552tMali Ivermectin (0 - 0.8) 0t4Niger Surveillance (0 - 8.e) 0.7720Senegal Ivermectin (t.s - 26.4) (0 - s3.5) 0.28 0.91 1 69 Togo Ivermecttn Larvrcrding + Ivemr.