1.Mosquitoes, ticks, houseflies, and probably human body lice were found to be susceptible to parenteral infection with West Nile virus. Chicken mites, bedbugs, rat fleas, hippoboscid flies, and cockroaches proved to be refractory.
2.Culex univittatus, C. antennatus, and C. pipiens were infected readily when blood having a virus titer of 4.5 was ingested. A titer of 2.5 was sufficient to infect many individuals.
3.C. pipiens and C. univittatus became infected and were capable of transmitting the virus when kept at mean daily temperatures of 12–23°C.
4.C. univittatus transmitted the virus as soon as 5 days after the infective blood meal and for at least 33 days thereafter at 28–32°C.
5.The tick Ornithodoros savignyi, when infected parenterally, transmitted the virus while biting infant mice, and the virus was isolated from the coxal fluid. This tick was also infected by feeding on the blood of infected mice, but failed to transmit the virus when infected in this manner. Ornithodoros erraticus and Argas persicus showed evidence of infection but did not transmit the virus.
Namru 3, Department of Entomology, c/o American Embassy, Cairo, Egypt.