TRENDS, PRIORITIES AND POLICY DIRECTIONS IN THE CONTROL OF VECTOR-BORNE DISEASES IN URBAN ENVIRONMENTS

The habitats available in urban environments tend to be rather lacking in diversity compared to those in the countryside, and relatively few species are able to exploit them. Those that can, however, often find themselves relatively well provided with food and places to live, and relatively free of competitors and predators. This applies not only t o such well-known species as the house-sparrow, but also to most of th e important mosquito vectors of human disease in urban areas. Human ci ty dwellers thus tend to be exposed to a different spectrum of disease than their rural counterparts. This review describes how the physical and social changes associated with urbanization have altered the tran smission of vector-borne disease. It concentrates on the important mos quito-borne infections: malaria, dengue and filariasis. Dengue virus v ectors breed in relatively clean water in man-made containers, while u rban filariasis vectors breed in highly polluted water, and these mosq uitoes have now been spread by man's activities to almost every tropic al city. With important exceptions, anopheline malaria vectors have no t generally succeeded in adapting to urban life, but malaria can still be a problem where there are rural pockets in the middle of town. Eac h of these problems requires control using different technologies and timing. The following policy implications are stressed. The areas of r esponsibility between different sectors of the local services (health, water supply, sanitation), and between these and the public, need to be clearly defined. Due to the biological complexities of vector-borne disease, decentralized primary health care systems are generally inca pable of ensuring that control efforts are adequately targeted in time and space. Community support is essential but specialized technical s kills are also required.