NO. I0 COCKROACHES—ROTH AND WILLIS 7 
tainly potential vectors of viruses. The experimental transmission of 
poliomyelitis virus from naturally infected cockroaches to susceptible 
hosts has been a particularly significant finding (Syverton et al., 
1952). These workers isolated four strains of poliomyelitis virus 
from four lots of cockroaches captured in two States on the premises 
of paralytic poliomyelitis patients. The cockroaches were the common 
domiciliary species: Blattella germanica, Supella supellectilium, and 
Periplaneta americana. This is apparently the first time cockroaches 
have been found contaminated with a virus in nature. 
Insect vectors apparently are only accessory to the general mode of 
spread of poliomyelitis, which is still unknown (Howe in Rivers, 
1948, 1952). The virus has frequently been recovered from house 
flies and filth flies during epidemics, but epidemics have built up and 
run their course during fly-control programs (Howe in Rivers, 1952). 
Epidemics continue into cold weather beyond the fly season, and peo- 
ple in clean suburbs with well-screened homes suffer to the same degree 
as those in slums (Howe im Rivers, 1948). Paffenbarger and Watt 
(1953) reported that fly-control measures which reduced the inci- 
dence of dysentery did not reduce the number of cases of poliomyelitis 
or affect the duration of an epidemic in Texas. They concluded that 
the major role in the spread of the epidemic was person-to-person 
contact between paralytic cases and susceptible hosts, directly or 
through an intermediary. Sabin (1951) concluded that the most im- 
portant route in poliomyelitis infection is the spread from person to 
person by the fecal-oral route and that contaminated food or drink, 
whether by humans or flies, is an important mode of entry. Theo- 
retically, transmittal of poliomyelitis virus by contaminated cock- 
roaches could fit into all of these situations, perhaps better than 
house flies. 
Cockroaches, being less obvious and less feared than flies, rarely 
are subjected to widespread eradication as have been flies. Cock- 
roaches are no respecters of homes and may be brought into the 
cleanest with groceries, in cases of beer, or may enter by migration. 
Cockroaches, unlike flies, breed indoors the year around, a fact that 
makes them potential vectors in winter when flies are dormant. Obvi- 
ously, much more work remains to be done before the role of cock- 
roaches as possible vectors of poliomyelitis can be ascertained. Yet 
the finding of poliomyelitis virus in three species of wild-caught cock- 
roaches (as opposed to laboratory-inoculated) suggests that a more 
concerted effort should be made to control cockroaches, as well as to 
determine their relation to this disease. 
The Coxsackie virus may retain its virulence in the American 
