[Current situation of yellow fever in Latin America]

Yellow fever endemicity is currently stabilized in South America: an average of 115 cases has officially been notified each year since 25 years (between 12 and 304 annual cases). These figures are underevaluated but no epidemic has been observed since 1983. Only sporadic or limited grouped cases have been reported. All declared cases correspond to people who have been infected within sylvatic areas, mainly adult forestmen. Within the last years, the majority of cases have occurred in Peru and Bolivia; the other cases have been observed in Brazil, in Columbia, in Ecuador and in French Guiana (imported strains from Surinam). This apparently low virus circulation may be due to massive campaigns of vaccination and to mosquito vector control. But this situation could suddenly reverse as observed in the past with yellow fever and the spring of the urban Aedes aegypti vector. Genetic and immunochemical heterogeneity has been demonstrated between South American and African yellow fever strains, which may reveal evolutionary divergence due to different ecological environment between the two continents. Yellow fever definitely remains a topical disease which requires a constant surveillance.