Analytical study of a Rift Valley fever epidemic.

Three epidemiological investigations were carried out during and after the 1987 Rift Valley fever (RVF) epidemic in South Mauritania: a case control study, a cross-sectional study in the town of Rosso and a cross-sectional study of villages and encampments around Rosso. The case control study showed an association between epizootic and epidemic outbreaks. The study in Rosso town showed housing and district effects. Also, a medical survey of hospital staff showed the absence of interhuman contamination. The cross-sectional study of villages and encampments around Rosso showed heterogeneity corresponding to a village and ethnic effect. The human epidemic was linked to epizootic disease, but the "vectors" of the disease are not as yet known.