|
|
|
POXVIRUS What
is feline poxvirus and what diseases does it cause? Feline
poxvirus is a member of the Orthopoxvirus group, which also includes vaccinia virus, the virus used as a
vaccine in the successful eradication of smallpox. The virus cannot be distinguished from cowpox virus, which
causes a rare infection on the teats and udders of cattle in this country.
In cats, the first sign of infection with feline poxvirus is the presence
of a single skin lesion, usually on the head, neck or forelimb.
This primary lesion can be anything from a small scabby ulcer to a large
abscess and may be itchy, causing the cat to aggravate it by biting and licking.
Within a few days to weeks of the appearance of the primary lesion,
widespread secondary skin lesions appear. These
start as small nodules which develop into ulcers which rapidly scab over and
heal, leaving small patches of bald skin. The
hair rapidly regrows and cats are usually normal six to eight weeks after the
primary lesion developed. In cats
with underlying immunodeficiency, such as that associated with feline leukaemia
virus or feline immunodeficiency virus infection, generalised infection with
feline poxvirus is likely, leading to progressively worsening lesions and
ultimately, death. Is
there any treatment for cats with feline poxvirus infection? There
are no antiviral drugs available that will alter the course of feline poxvirus
infection in cats. Corticosteroids
are positively out of the question since they exacerbate the disease, leading to
generalised infection and death. Antibiotics
may be useful to reduce the likelihood of delayed healing of lesions due to
secondary infection by bacteria. Euthanasia is recommended in cats showing progressive,
generalised infection Is
there a vaccine available? No
vaccine is available for use in cats. The
use of vaccinia virus as a vaccine is now strictly controlled since the
eradication of smallpox, because vaccinia virus itself is pathogenic for man.
In cattle and man, vaccinia virus does not give good protection against
cowpox virus, and it may also be ineffective in cats.
Development of a specific vaccine against feline poxvirus is unlikely at
present because the infection is still very rare in cats. Can
the virus be spread to other cats or humans? Cat
to cat transmission under natural conditions has not been proven, but is a
possibility. It is believed that
cats become infected with feline poxvirus after being bitten by a rodent
carrying the infection. The rodent
reservoir in the UK. has not been
positively identified, but there is some evidence that certain species of vole
and mouse are the natural hosts. Feline
poxvirus infection is more common in hunting cats, and the primary lesion often
appears at the site of a bite. Moreover,
the incidence of cases peaks in late summer and autumn when rodent populations
are at their peak, and are very rare in the depths of winter when rodents are
hibernating. Man
is susceptible to infection with feline poxvirus, and about half of all human
cases can be attributed to contact with an infected cat.
In man the disease usually consists of a single lesion on the hand or
face, sometimes with other symptoms such as fever or headache.
Feline poxvirus infects through cuts and abrasions on the skin, but is
not highly infectious, so the risk of human infection can be greatly reduced by
taking basic hygiene precautions like wearing gloves when handling infected
cats. Cats are infectious until the
scabs have dropped off. |