Vectors and Natural Reservoirs of Oropouche Virus in the Amazon Region

In 1977 a program of field and laboratory studies was initiated to study Oropouche virus in the Amazon region of Brazil. This virus is a frequent cause of urban epidemics of a febrile disease in this region and Culicoides paraensis has been incriminated as the vector. This research program includes (1) surveillance of forest vertebrates and invertebrates near Santarem, Brazil to detect the natural reservoirs and vector(s); (2) studies on the biology and population dynamics of C. paraensis in the urban environments of Belem, Brazil, (3) laboratory studies at the Evandro Chagas Institute to evaluate vector potential of various hematophagous insects in transmission tests, and (4) efforts to colonize the various potential vector species with emphasis on C. paraensis. The C. paraensis have efficiently transmitted virus in the laboratory. The other candidate vector Culex quinquefasciatus were not efficient vectors under laboratory conditions. Observations have been made on the biology of the midges in the field and laboratory. The field surveillance program was established and antibodies to the virus have been found in one monkey.