Evaluation of enemas for exposing Aedes aegypti to suspensions of dengue-2 virus.

To determine if enemas could be used to simulate oral exposure of Aedes aegypti to dengue-2 virus, we compared infection rates of mosquitoes administered an enema of a blood suspension containing dengue-2 virus to infection rates in mosquitoes that imbibed the same suspension from a drop of blood. In 1 of 4 experiments infection rates were significantly different. More importantly, during 2 of the 4 trials, 100% of the mosquitoes in the enema treatment group were infected. We speculate that the capillary tube used to administer the enemas abraded the hindgut of mosquitoes in the groups with 100% infection rates and, therefore, virus was inoculated directly into the mosquitoes' hemocoel. We conclude that the method we used for administering enemas cannot be used to simulate oral exposure of Ae. aegypti to dengue-2 virus.