[Aedes albopictus (S) in the region of São José do Rio Preto, SP, Brazil: a study of its infestation in an area where Aedes aegypti was already established and a discussion of its role as a possible vector of dengue and yellow fever].

The objectives of this survey were to study the evolution of Aedes albopictus infestation in São José do Rio Preto region, SP, an area already occupied by Aedes aegypti and also to discuss its role in transmitting diseases. Analyzing data from urban mosquito larval density surveys of the region's municipalities, year and site of the occurrence, composition and location of larval samples, breeding containers and Breteau indices were studied. By May 2001, the vector was found in 96 of 100 municipalities. Aedes albopictus compared with Aedes aegypti was found in greater proportions close to dwellings and presented greater degrees of association in natural and discarded containers. Endemic behavior of dengue, occurrences of local cases of sylvatic yellow fever and recognized competence of the vector's transmission of these diseases suggest the necessity to consider its possible participation in the transmission of dengue and the re-urbanization of yellow fever.