Vesicular stomatitis is an acute viral vesicular disease of
cattle, horses, deer and pigs (and occasionally humans). The etiologic
agent, vesicular stomatitis virus (VSV), is a rhabdovirus. There
are 2 serotypes of VSV, New Jersey and Indiana. Infection with
one serotype is not cross-protective for the second serotype.
VSV versus the other vesicular disease viruses of livestock:
Vesicular stomatitis virus infection resembles foot-and-mouth
disease when it occurs in cattle, and the other viral vesicular
diseases when it occurs in pigs. However, VSV is the only one
of the
"Big 4" viral vesicular diseases of livestock
(foot and mouth disease virus [FMDV], swine vesicular disease
virus [SVDV], vesicular exanthema of swine virus [VESV] and VSV)
that infects horses (inoculation of a horse's tongue was historically
used to differentiate VSV from the others). VSV is also the most
important of these 4 viruses as a zoonotic agent for humans.
- Most experts agree that humans can harbor FMDV in their pharynx
for 24-36 hours, and possibly as long as 5 days. In addition,
there are a very small number of documented cases (40 cases between
1921-1969) of actual human infection with FMDV, associated with
mild flu- like illness and mild vesicular lesions. Infected people
may shed virus for up to 14 days and may serve as a source for
infection of other animals, but the risk of such biological transmission
is considered "negligible" by the USDA.
- FMD is NOT the same as hand, foot, and mouth disease in human
children. Hand, foot, and mouth disease is, like FMD, caused
by infection with a picornaviruses, but picornaviruses distinct
from FMDV (such as the Coxsackie viruses and enterovirus 71).
- SVDV can cause a mild flu-like illness in humans.
- VESV and related viruses from marine mammals have been reported
to cause vesicular lesions on the hands and feet in humans.
Vesicular stomatitis virus is primarily viewed as an arbovirus.
- Phlebotomine sandflies are confirmed biological vectors of
VSV.
- The virus has also been found to replicate in Culicoides
midges and Simulium blackflies.
- However, VSV can also be spread by direct contact among infected
pigs. (See Stallknecht et al. 1999)
Although often treated as an
"exotic" disease
to the U.S., there is one enzootic focus of VSV in the country
(Ossabaw Island just off the Georgia coast), and outbreaks of
VSV infection occur periodically in the western U.S.
- Outbreaks in the U.S. are thought to originate with the movement
of animals and/or insect vectors from Mexico.
- Major outbreaks have occurred repeatedly in the U.S. over
~10 year cycles, with disease occurring for 2-3 years and then
disappearing again for ~10 years.
- In 1995, 367 VSV (+) premises were reported in the southwestern
U.S. and there were cases of VSV infection in horses in the southwestern
U.S. again in 1997 and 1998.
VS in horses, cattle and swine:
- fever 24-48 hours after infection
- oral
vesicles and inflammatory lesions at the coronary band
- Rupture of the oral vesicles leads to pain, excessive salivation
and inappetance.
- The coronary band lesions lead to lameness.
Diagnosis in livestock:
- virus isolation from vesicular fluid
- serology
Control of outbreaks is dependent upon rapid recognition of
initial cases, quarantine and restriction of movement of infected
and in-contact animals, and insect control. There are no commercially-available
VSV vaccines in the U.S., but an autologous vaccine was made in
1995 to help control that outbreak. Several inactivated vaccines
containing both the Indiana and New Jersey serotypes are used
in Central and South America.
VS in humans:
- flu-like symptoms
- less commonly, oral vesicles and cervical lymphadenopathy