Abstract

River blindness (onchocerciasis) is one of the most debilitating diseases of Africa. While the application of pesticides has successfully reduced the density of the insect vector in the savannas of West Africa, the approach is not considered to be practical in the populated forest zones, which are of enormous importance to agriculture. This project will attempt to break the cycle of insect vector - parasite - human host infection through mass treatment with a new drug, Invermectin. Researchers will assess the drug's effectiveness in reducing the transmission of onchocerciasis in the forested and small river abundant Danane region of Côte d'Ivoire. Specifically, it will evaluate the distribution (i.e. prevalence and density) of microfilaria before treatment and at different intervals after treatment. It will also estimate the costs of a treatment campaign using Invermectin. The results of the project will enable the government to implement new strategies to reduce the risk of onchocerciasis, and open up new regions for agriculture.

Post-Project Summary

The study was carried out by a multidisciplinary team of entomologists, assisted by statisticians, a demographer, a cartographer and an economist. Of the 2 703 people surveyed, 2 355 had blood-free skin snips. Parasitological examination of these revealed 1 416 positive snips. These data indicated that for the whole zone, the presentation rate was 87.12%. Microfilaria infestation was slightly higher in men (53.76%) than in women (46.33%), and higher in adults (61.06%) than in children (38.94%). Of the 2 554 individuals who underwent pretreatment examination, after applying the exclusion criteria, only 1 848 actually took Ivermectine (150 mcg/kg single dose). The presentation rate for treatment was 94.48% for the whole zone, but 97.72% in the village most severely affected, which shows that mass treatment was well received by the public. An epidemiological control evaluation of the entire population was carried out 6 months after treatment. Of 1 759 biopsies, 621 were positive. Follow-up of 30 onchocerciasis victims showed that the microfilarial load had dropped 3 months after treatment, but had risen slightly at 6 months and at 12 months. The effect of treatment on transmission was also apparent. The average percentage of females infected was 20 to 25% before and 11.38% after treatment. The mass treatment made it possible to determine the average cost of the various components of a treatment campaign. The project offered an opportunity for the Côte d'Ivoire ministries of health, and education and scientific research, and the Organization for Coordination and Cooperation in the Control of Major Endemic Diseases (OCCGE) to pool their efforts in the search for a solution to the problem of forest onchocerciasis in West Africa.

Recipient Institution(s)