Impact of combined large-scale ivermectin distribution and vector control on transmission of Onchocerca volvulus in the Niger basin, Guinea.

As part of the WHO Onchocerciasis Control Programme in West Africa (OCP), the attack phase of operations in the Niger basin in Guinea began in 1989 with the simultaneous use of ivermectin and vector control. Larvicide applications coupled with annual large-scale ivermectin distribution have greatly reduced blackfly infectivity (by 78.8% for the number of infective larvae per 1000 parous flies). The combination of vector control and ivermectin has permitted excellent control of transmission. In the original OCP area, it took 6-8 years of vector control alone to obtain an equivalent decrease in blackfly infectivity. For the same number of flies caught, transmission was much higher in areas where ivermectin had not been distributed. The combined use of ivermectin and vector control has opened up new prospects for carrying out OCP operations with, notably, the possibility of reducing larviciding operations

Trente ans de lutte contre l’onchocercose en Afrique de l’Ouest. Traitements larvicides et protection de l’environnement

La lutte contre l'onchocercose, ou cécité des rivières, une maladie parasitaire endémique, fut entreprise en Afrique de l'Ouest dans une perspective do développement durable. Tous les moyens technologiques disponibles ont de ce fait été mobilisés pour le contrôle du vecteur, une simulie, puis du parasite responsables de cette maladie, par le Programme de Lutte contre l’Onchocercose en Afrique de l'Ouest (OCP). La lutte antivectorielle consistant en épandages d’insecticides chimiques sur les sites de développement de la simulie dans les rivières, il est apparu indispensable d’assurer la sauvegarde de l’environnement aquatique qui fournit aux communautés riveraines eau et ressources biologiques. Les technologies les plus modernes ont été mises en œuvre dès leur mise au point, pour combattre la maladie, contribuant ainsi à la protection de ce milieu. Le programme de surveillance écologique des rivières traitées par des larvicides anti-simulies a été mis en place dès le lancement d’OCP. et assuré par des spécialistes de I' hydrobiologie des pays africains participants du Programme, sous la supervision d’un groupe international d’experts indépendants, le Groupe Écologique. OCP est incontestablement un succès aussi bien pour ce qui est du contrôle de la maladie que de la protection de l'environnement. Il est l'exemple unique au monde d’un programme de santé publique de longue durée qui depuis son origine a mis en œuvre tout ce qui était possible pour harmoniser les enjeux de l’amélioration de la santé et ceux de la protection de l’environnement. Il s'est achevé avec la satisfaction de laisser aux générations montantes un environnement non dégradé et des vallées libérées de l’onchocercose, qui permettront d’accroître la productivité agricole des pays africains.The control of onchocerciasis, or river blindness, an endemic parasitic disease, was implemented in West Africa in the perspective of sustainable development AH the available technological means to fight this disease, by way of the control of its blackfly vector, then its parasite, were therefore implemented by the Onchocerciasis Control Programme in West Africa (OCP). Vector control being achieved through applications of chemicals on its river breeding sites, it was necessary, at the same time, to fight for the preservation of the aquatic environment, which supplies the communities that live along the rivers with water and biological resources. This was the spirit in which the OCP was set up and implemented, and the most modem technologies were used as they become available to fight the disease, thus facilitating the preservation of the aquatic environment. This Programme has indisputably been a success as regards the control of the disease as also from the point of view of the preservation of the environment The aquatic monitoring programme of the rivers under treatment with anti-simulid larvicides was set up right from the very beginning, and performed by national experts of the Participating Countries of the Programme, under the aegis of a group of international independent experts, the Ecological Croup The Onchocerciasis Control Programme in West Africa is an unique example in the world of a long-term public health programme which has made every effort possible from its inception to adequately combine health and environment issues. It ended with the satisfaction of bequeathing to the coming generations a non degraded environment and valleys freed from onchocerciasis which would increase the agricultural productivity of the countries