An overview of arbovirology in Brazil and neighbouring countries

The main aspects of the clinical manifestations and epidemiological data regarding human arboviruses in the Brazilian Amazon region are reviewed. Thirty-six arboviruses and other viruses of vertebrates have been associated with human disease among over 200 isolates made in Brazil. Five of them are important in public health and are involved in epidemics, they are the Dengue (DEN), Mayaro (MAY), Oropouche (ORO), Rocio (ROC) and Yellow Fever (YF) viruses. ORO and DEN are associated with epidemics of human disease in urban areas, while MAY, ROC and YF have been responsible for epidemics in rural areas. Usually, ORO causes a febrile disease, sometimes accompanied by aseptic meningitis. MAY and DEN are associated with febrile disease and rash, while YF produces a hemorrhagic fever and ROC is an agent responsible for encephalitis. Thirty-one other arboviruses are involved in rare and sporadic cases of febrile illness. All arboviruses (with the exception of DEN and arenaviruses) are maintained by a slyvatic cycle in the forest, where several species of hematophagous insects act as vectors and wild vertebrates are involved as hosts. DEN has a cycle in which the #Aedes aegypti$ mosquitoes are the vectors and man the vertebrate host. Arenaviruses are transmitted directly to man by rodents. With the exception of the five viruses associated with epidemics which are of great economical and social impact, and may be responsible for deaths, (e.g. of DEN,; ROC and YF), the exact involvement of these viruses as systematic agents of human disease is unknown. Further studies are needed to clarify aspects of their epidemiology. Arenaviruses are directly transmitted to man by way of the excreta of infected rodents which are the reservoir-hosts of these viruses. Appropriate safety measures should be adopted when handling these viruses as they can be transmitted via the respiratory tract (droplet infection). (Résumé d'auteur