Infective larvae of Brugia: escape from mosquitoes into water and subsequent oral infectivity in jirds.

Published work showed that third-stage larvae (L-3s) escape into water from dead or dying, Brugia pahangi-infected, Aedes aegypti. The present study revealed the same escape phenomenon among B. pahangi-infected Armigeres subalbatus, Anopheles quadrimaculatus, and Aedes togoi, and among Brugia malayi-infected Ae. aegypti and Ae. togoi. L-3s maintained in water or in Lum's solution for 3 hours retained infectivity when tested in orally or subcutaneously exposed jirds; furthermore, L-3s recovered from mosquitoes dead for 24 to 48 hours were also infective by either portal of entry in jirds. Since L-3s may escape and remain infective in the field, it is conceivable that natural filarial infections might thus be acquired orally by definitive hosts.