Infection of pigeons by airborne Venezuelan equine encephalitis virus.

The experiments described were designed to provide information on the infectivity of Venezuelan equine encephalitis (VEE) virus for birds by the respiratory route. Laboratory studies by Chamberlain (2) showed that wild birds, including pigeons, could be infected with VEE virus by mosquito bite or by subcutaneous (sc) injection of virus. Overt signs of disease were absent in avian hosts, but viremia was produced for periods of 1 or 2 days, followed by the appearance of specific serum-neutralizing (SN) antibodies. The respiratory route of infection with VEE virus has been suggested previously. In noting that virus occurs in the nasopharyngeal washings of infected humans, Olitsky and Casals (10) recognized a potential for epidemics without insect vectors. Perhaps the most striking evidence of invasiveness of VEE virus by the respiratory route was provided by Slepushkin (11), who reported on infections in a large group of laboratory personnel after exposure to aerosols produced by breakage of a vial of virus. The susceptibility of birds to infections by the respiratory route had not been investigated. However, the possibility that the respiratory route was involved with arboviruses in nature was suggested by Holden (6) in studies with pheasants and eastern equine encephalitis (EEE) virus. Other cases of contact infection among birds by EEE and western equine encephalitis viruses were reviewed by Bourke (1).