Attempts to Determine the Amount of Yellow Fever Virus Injected by the Bite of a Single Infected Stegomyia Mosquito

Summary and Conclusions 1. Stegomyia mosquitoes infected with yellow fever virus were induced to feed upon new-born white mice. The latter were immediately killed and extracted. The extracts were injected in graded doses into rhesus monkeys. 2. In two experiments the titrations indicated that each mosquito injected during the act of feeding at least 100 infective doses of virus. 3. Mosquitoes from one lot, which was later used in a feeding experiment on a mouse, were titrated immediately following the infective blood meal and again after ten days. A decrease in titer during the interval confirmed previous observations. Yellow fever virus within the mosquito body appears not to increase, but rather to diminish in quantity. 4. From a comparison of the amounts of virus in the whole insects and in the baby mouse after being fed upon by mosquitoes from the same lot, it is shown that probably about 1 per cent of the total virus content was injected at the time of biting.