CONCERNS IN BRAZIL FOR FUTURE URBAN YELLO W-FEVER OUTBREAKS TRANSMITTED BY VECTORS OF DENGUE - AEDES-AEGYPTI AND AEDES-ALBOPICTUS

Urban yellow fever (YF) epidemics have disappeared from Brazil since a bout 50 years, but a selvatic cycle still exist. In many States, cases are more or less numerous each year. Ae. aegypti was eradicated in 19 54, re-appeared temporarily in 1967, and then definitively in 1976-197 7. Ae. aegypti is a vector of yellow few (YF), but also of dengue, den gue, whose first cases were reported in 1982. Today, dengue is endemic in many regions. A second Flavivirus vector Aedes albopictus is prese nt since about ten years in some States from which Sao Paulo. The anal ysis of the YF cases between 1972 and 1994 allowed us to determine the epidemiologic regions. In the first region, the endemic area, the YF virus is circulating a silently,, among monkeys, and the emergence of human cases is rare. In the second region, the epidemic area, some epi zootics occur in a move or less cyclic way, and human. cases cart be n umerous. Nevertheless, these outbreaks are considered <<selvatic>> epi demics, as long as Ae. aegypti is not concerned From the Amazonian reg ion, the virus moves forward along the forest galleries of the Amazone tributaries, from North to South. Actually dengue epidemics appear in quite all Stares, and reflect the geographical distribution of Ae. ae gypti. Recently, Ae. aegypti was found in the southern part of the Par a State, in the Caraja's region considered to be the source of the mai n YF epidemics. In another hand, Ae. albopictus is now increasing its distribution area specially in the suburban zones. The ecology of this potential vector, which seems to have a great adaptative capacity, gi ve this vector art intermediate position between the forest galleries, where the YF virus circulates, and the agglomerations infested with A e. aegypti. Since a few years, the possibility of urban YF is threaten ing Brazil, it is more and more predictable and we must survey very ca refully the epidemiological situation in some regions of the country.