Biology Reference
In-Depth Information
This virus has gained notoriety over the past few decades, and is often greatly
misunderstood by the general public as well as by veterinarians, physicians
and animal managers (Abbott,
2008
; CDR,
2000
; Ritz
et al
.,
2009
). B virus,
which is enzootic in macaques, is a close relative of the Herpes Simplex Virus
endemic in human populations. In macaques, B virus can cause intermittent
eruption of mucosal ulcers but otherwise typically remains latent in dorsal root
and trigeminal ganglia of infected animals (Eberle and Hilliard,
1995
). Within
macaque populations, B virus is thought to be transmitted horizontally through
bites, sexual contact, and mucosal contact with infectious body fluids (Hilliard
and Ward,
1999
).
There are very few studies of B virus seroprevalence in macaques outside
of a laboratory setting. Among pet macaques in Asia, the prevalence appears
to be much lower than that seen in temple or free-ranging populations (Jones-
Engel
et al
.,
2006c
). The low seroprevalence rate we observed among the pet
macaques is likely attributable to the young age at which pets are typically
taken from the wild. These very young animals typically do not engage in
aggressive and sexual behaviors that are likely to lead to infection with B virus.
Weigler and colleagues detected antibodies to B virus in only 22 percent of
laboratory macaques < 2.5 years of age, but in 97 percent of the macaques
older than 2.5 years of age (Weigler
et al
.,
1993
). This same pattern of increas-
ing seroprevalence with age has been seen among populations of free-ranging
macaques (Engel
et al
.,
2002
; Jones-Engel
et al
.,
2006a
; Kessler
et al
.,
1989
).
Importantly, although infection rates are high as determined by the presence
of antibodies, rates of viral shedding are very low (Weigler
et al
.,
1993
; Weir
et al
.,
1993
). In laboratory settings it is estimated that 2-3 percent of animals in
a group may be shedding the virus at any one time (Elmore and Eberle,
2008
;
Huff
et al
.,
2003
). It is hypothesized that stress associated with captivity and/
or the breeding season (e.g., rhesus and Japanese macaques (
M. fuscata
) may
increase the likelihood of shedding in an animal) (Elmore and Eberle,
2008
;
Mitsunaga
et al
.,
2007
). We have performed viral culture on mucosal speci-
mens from hundreds of long-tailed macaques from free ranging populations
in Asia and have yet to find evidence of active viral shedding (Eberle
et al
.,
unpublished data).
B virus' notoriety as a human pathogen can be traced to its identification
as the etologic agent of more than 40 documented cases of severe menin-
goencephalitis, 70 percent of which resulted in death, among workers at
primate laboratories and/or zoos (Huff and Barry,
2003
). The most recent
reported case of human Herpes B infection occurred in 1996 and involved a
laboratory researcher who developed severe disease and died after acciden-
tal mucosal contact with body fluids of a rhesus macaque. Previous cases of
human herpes B infection have been attributed to contact with long-tailed
and rhesus macaques, though it should be noted that in all cases of human
