Malaria and urbanization in central Africa: the example of Brazzaville. Part I: Description of the town and review of previous surveys.

For a growing number of citizens, the upheavals caused by rapid urban development completely transform malaria epidemiology in tropical Africa. This paper is the first of a series on this phenomenon in Brazzaville, capital of the Congo Republic, where a third of the country's population is already concentrated. After describing the main human and physical geographical aspects of the town, the most significant results of the previous studies of this town and the surrounding rural area are reviewed. They show the existence, until the beginning of the 1950s of a stable, holoendemic situation characterized by a malaria prevalence approaching 90% in children in both urban and rural areas. Since then the intensive development of anti-malaria campaigns in urban areas over about ten years led temporarily to a considerable decrease in the level of endemicity, while in rural areas it remained unchanged. In the 1960s, the vector control and systematic chemoprophylactic measures gradually stopped, permitting the study of a new malaria dynamic related only to the evolving particularities of a changing urban ecosystem.