[Agriculture-health interface in the field of epidemiology of vector-borne diseases and the control of vectors].

This paper is a review of the interactions between agriculture and vector borne diseases. Rain forest clearing makes possible the development of heliophilous species of anophelines and snails leading to an increase of malaria and schistosomiasis in Africa. But in Asia, clearing is a control method against Anopheles balabacensis, an important malaria vector. Clearing of forest galleries is followed by the disappearance of shore-dwelling tsetse flies. Woodcutters and pioneer farmers are contaminated with arbovirus and leishmaniasis when entering in natural sylvatic foci of these diseases. Management of drinking water reduces guinea worm as well as cholera and other diarrhoeal diseases. More over when piped water becomes available people are no more obliged to store drinking water in containers where vectors use to breed. Reservoirs of dams offer large possibilities for the development of mosquitoes including anophelines vectors of malaria and filariasis and of snails hosts of schistosomiasis. The medical importance of these man-made breeding sites depends of the local epidemiological features of the diseases. Dam spillways provide breeding for blackflies and man-made foci of onchocerciasis have been described in West Africa. Irrigation channels mainly when non cleared of vegetation are good breeding places for anophelines and snails. Irrigated surfaces like rice fields are highly productive in anophelines and other dangerous species of Culicinae. Insecticides used in agriculture, mainly to control cotton and rice pests, have been at the origin of insecticide resistance of several anopheline species. On an other hand, sometimes rice pests control lead to the control of rice field mosquitoes until they become resistant, e.g. for Culex tritaeniorhynchus the vector of Japanese encephalitis in South Korea. Many international organizations have emphasized the role of intersectorial collaboration to control man-made vector borne diseases foci. Good planning of the infrastructures (e.g. twin spillways) and adequate maintenance are essential. Vector control in rice field is a puzzling question. Wet irrigation was a hope but it cannot be done everywhere. Biological control methods have not been proven to be very efficient. Even Bacillus thuringiensis H14 and B. sphaericus have severe limitation. New tools for intersectorial activities should be a goal for scientists imagination.