Yellow fever

Abstract

Yellow fever remains as an important threat in sub-Saharan Africa and South America, the regions where it is endemic; the yellow fever virus has periodically stricken human and nonhuman primates’ population, its urban and jungle hosts, when epidemics and/or epizootics are registered, respectively. These periodic expansions and retractions in both endemic regions are not completely understood, but several factors play a role including a heavy rainy season, the number of vectors, and the level of immunity coverage conferred by 17D vaccine use. The mosquito vectors are different for urban and jungle cycles for Africa and South America, and several sylvatic Aedes and Haemagogus species are its vectors, respectively. In urban settings the only vector is the peri-domestic Aedes aegypti. Nonetheless, only in Africa a third intermediate (rural) cycle is vectored by Aedes simpsoni. The diagnostic of yellow fever is made by molecular approaches (RT-PCR and real-time RT-PCR), virus isolation (cell culture), serology (IgMELISA), and immunohistochemical assay on tissue of fatal cases. Treatment is only supportive, and the prevention should be focused on vaccination of people living in or moving to endemic areas. These aspects are discussed in this chapter. Although several taxonomic modifications have been proposed on Culicidae genera, mostly splitting Aedes mosquitoes into different genera, this taxonomy putting all Aedes in a single genus has been used in the yellow fever chapter. To facilitate utilization by health personnel, all new aedine genera can be considered Aedes (CBM).