Attempts to Transmit the Virus of Acute Anterior Poliomyelitis Through Aedes aegypti

Abstract

In experiments performed at the Army Medical School, Kelser has shown that Borna disease, or epidemic equine encephalomyelitis, can be transmitted by the mosquito Aedes aegypti. This suggested the advisability of reconsidering the abandoned theory of insect transmission in poliomyelitis, using mosquitoes of the genus Aedes or other insects not previously considered. Poliomyelitis presents certain epidemiological features which have suggested insect transmission: (1) it is claimed that all outbreaks, even those that extend into the winter months, begin during the summer; (2) relatively few cases can be traced to previous cases or carriers, and the incidence of infection among contacts is low; (3) the rural distribution of the disease usually equals or exceeds urban incidence; and (4) many outbreaks occur in the neighborhood of water or water systems. Arguments advanced against this possibility include: (1) the virus has not been demonstrated in the blood of human patients, and only in small amounts in the blood of monkeys; (2) large amounts of virus have been required to infect monkeys injected by the intravenous route; (3) with one exception virus has not been demonstrated in filtered saline suspensions of insects previously fed on infected human beings or monkeys; and (4) such transmission experiments as have been reported indicate that biological transmission does not occur. In experiments based on the inoculation into normal monkeys of filtered saline extracts of insects which had previously fed on materials containing virus, it has been shown that the virus survived in Musca domestica as long as 48 hours (Flexner and Clark; Howard and Clark; that adult Musca domestica and Calliphora vomitoria developed from larvae grown on infected tissues gave negative results (Noguchi and Kudo); and that virus was not demonstrable in Culex pipiens, C. sollicitans, or C. cantator (Howard and Clark).