Cyclic passages of jungle yellow fever virus strains were successfully made by using Metachirus nudicaudatus and Marmosa cinerea as animal hosts and Aedes aegypti as the insect vector.
One jungle yellow fever strain which was isolated from a marmoset captured in a region where the disease is endemic was found to be better adapted to passage through metachirus than was a strain obtained from a human infection during a transient outbreak of jungle yellow fever. After repeated passage, by means of mosquitoes, through marmosets and metachirus, this latter strain apparently became more suited to passage through metachirus and was thereafter maintained in cyclic passage through metachirus without difficulty.
While these marsupials are easily infected with yellow fever virus through the bite of the infected mosquito vector, they do not so readily or so consistently infect normal mosquitoes as do two species of marmosets which were previously studied.
The epidemiological implications of these observations are discussed.