18 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 134 
cockroach for 15 days after being ingested (Fischer and Syverton, 
1951a). The “C” viruses have been recovered in feces and from 
sewage in cities where Coxsackie infections had occurred, which sug- 
gests that cockroaches might be vectors as they have ample opportunity 
to acquire the virus in sewers. 
Although Findlay and MacCallum (1939) reported that yellow- 
fever virus retained its activity when injected into the abdomen of 
Blattella germanica, they did not suggest that cockroaches necessarily 
play any part in the epidemiology of yellow fever. However, they 
point out that monkeys supplement their diets with insects and suggest 
that it would be of considerable interest to determine the natural 
animal foods of monkeys in yellow-fever areas. It would also be of 
interest to determine whether these monkeys could be infected with 
yellow fever by eating cockroaches that had been injected with the 
virus ; this experiment apparently was not run. 
We have found several records (e.g., see section on helminths, 
pp. 27, 95, 105) of monkeys feeding on cockroaches, but only the 
following reference indicates how cockroaches might acquire the 
yellow-fever virus in nature. Whitfield (1940) stated “. . . cock- 
roaches are omnivorous, and no considerable employment of the 
imagination is necessary to see a possible connection between dead 
mosquitoes, excreta from other sick monkeys, and general detritus, 
etc., infected with the virus; scavenging cockroaches, and monkeys 
catching the cockroaches. The possibilities of such a cycle of infection 
are not confined to the laboratory, and it is reasonable to suppose that 
infection via the alimentary canal may possibly be a contributory 
cause of jungle or rural yellow fever.” 
Yellow fever is basically an infection of the hemapoietic system ; 
during the first 3 days of fever, the virus is readily available to certain 
blood-sucking mosquitoes in which it must multiply for about 12 days 
before the mosquito can transmit it by bite. (Theiler im Rivers, 1948; 
Herms, 1939). Cockroaches have been known to bite man (see 
pp. 30-32), yet we do not know definitely whether they imbibe blood. 
Cockroaches have been known to gnaw on the extremities of dead 
and dying humans (Drury, 1782), but the virus has only once been 
isolated from a man dead of yellow fever (Theiler im Rivers, 1948). 
Cockroaches are known to feed on dejecta, but it has been conclusively 
shown that dejecta from yellow-fever patients are not factors in the 
epidemiology of yellow fever (Herms, 1939). There remains, of 
course, the unanswered question, can cockroaches be infected with 
yellow fever perorally? There would seem to be no other way in 
which they could become infected in nature. Findlay and MacCallum 
injected the virus into their cockroaches parenterally. 
