970 
ANIMAL DISEASES 
mental inoculation but there is no evidence 
that SV41 causes disease under natural condi- 
tions. 
NONSIMIAN VIRUSES IN SIMIANS 
Following are a number of nonsimian vi- 
ruses capable of infecting simians : 
Arboviruses — Several arboviruses are known 
to produce infection and/or death in monkeys 
and apes: yellow fever, Kyasanur forest and 
dengue. Of questionable concern is the fact 
that monkeys and apes all come from areas 
known to be endemic arbovirus areas. It is sur- 
prising that there has not been a greater recog- 
nized involvement of these animals with arbo- 
viruses. All these viruses are vector borne and 
antibody surveys ^^-^^ certainly indicate that in- 
fection of nonhuman primates (and probably 
disease) results from many arboviruses. Yet 
actual knowledge regarding the infectivity of 
arboviruses for simians has been limited. 
Yellow fever virus is highly lethal for man 
and monkey alike. Jungle yellow fever is de- 
pendent upon involvement of monkeys in the 
infectious cycle. Here the disease is undoubtedly 
enzootic in monkeys (probably other forest ani- 
mals as well) and is transmitted and maintained 
from one animal to another by forest dwelling 
mosquitoes. Different species of monkeys are 
involved in the various endemic areas. In man 
and monkeys, yellow fever infection is usually 
inapparent. Epidemics occur with irregular fre- 
quency and may result in high attack and mor- 
tality rates in both the human and simian 
populations. It is conceivable, although Public 
Health regulations are designed to prevent this, 
that infected animals might be imported. Vac- 
cination or appropriate mosquito-proof housing 
is effective but frequently both mechanisms may 
break down. The available vaccines are effective 
but the chick embryo preparation is highly labile 
and prevention of its deterioration is essential 
to maintain its efficacy.^^ 
Work et al.^" isolated a virus from a dead 
langur monkey found in the Kyasanur forest in 
South India. Infection of both man and monkeys 
with this agent results from a tick (Haemaphy- 
salis) bite. Shah''^ has shown the presence of 
virus in experimentally lactating monkeys and 
infection has been transmitted to a baby mon- 
key by breast feeding. Antibody surveys have 
determined that survivors among the different 
monkey species do occur. Because of lack of vec- 
tors, this disease probably would not spread in 
the U.S. but again it is possible to import in- 
fected animals. However, this disease is similar 
to other tick-borne virus encephalitides and the 
epidemiology of this group is in need of 
clarification. 
The status of the numerous other arboviruses 
is still not clear. Serologic studies suggest that 
many viruses very probably cause infection 
and/or disease in primates. The extent to which 
this happens is still unknown. It is fairly cer- 
tain that disease outbreaks are infrequent or 
more would have been detected. It is also pos- 
sible that lack of interest and study has con- 
tributed to the limited knowledge concerning 
infection and/or deaths of monkeys and apes 
in nature. In this regard it is interesting to 
note that a true simian arbovirus has yet to be 
described. 
Hepatitis — In 1961, Hillis reported an out- 
break of hepatitis in Air Force personnel han- 
dling chimpanzees. This finding of a chimpan- 
zee-human relationship has now been well 
documented with numerous reports demonstrat- 
ing the occurrence of hepatitis in individuals 
closely associated with this species — usually 
young, newly imported animals. The epidemiol- 
ogy of this disease is not clear and it is possible 
that the chimpanzee becomes infected as a con- 
sequence of associating with humans (or their 
products) in their natural habitat. Experi- 
mental infection of other species of simians, 
for example patas monkeys ^^"^^ and marmo- 
sets,®*-^^ has also been reported but needs fur- 
ther study. 
The recent description of an agent (Australia 
antigen) by Blumberg et al.'^^ that appears to be 
closely related to if not the same as this virus 
has also precipitated studies in monkeys and 
apes. Serologic investigations of sera from lim- 
ited numbers of nonhuman primates suggest 
with fair certainty that the apes (chimpanzees, 
orangutans, and gibbons) have circulating an- 
tigen and perhaps antibody. The status of mon- 
keys is not as clear, but in general they do not 
appear to have antibody. Deinhardt®^ has re- 
