Natural rabies virus
infection in hamsters (and in rodents in general) are highly exceptional.
Rodents in general do not develop rabies because they do not survive the
effects of the bite from the rabid dog or cat that gave it to them. Small
rodents (such as squirrels, rats, mice, hamsters, guinea pigs, gerbils,
and chipmunks) and lagomorphs (such as rabbits and hares) are almost never
found to be infected with rabies and have not been known to cause rabies
among humans in the United States. Bites by these animals are usually not
considered a risk of rabies, unless the animal was sick or behaving in
any unusual manner, and rabies is widespread in your area. However, from
1985 through 1994, woodchucks accounted for 86 percent of the 368 cases
of rabies among rodents reported to CDC. Woodchucks or groundhogs (Marmota
monax) are the only rodents that may be frequently submitted to state
health departments because of a suspicion of rabies. In all cases involving
rodents, the state or local health department should be consulted before
a decision is made to initiate post exposure prophylaxis (PEP). Refraining
from PEP of persons allegedly bitten by rodents might lead to tragic consequences,
as shown, for example, in a 1996 case in which a 20 year old man became
ill 5 weeks after being bitten while asleep outdoors in Northern Israel
by an unidentified small animal, which, according to his description, was
a rat or a mouse. Since injuries by these rodents do not require antirabies
treatment, no antirabies PEP was given. The patient subsequently died of
rabiesref.
Later, it was concluded, on the basis of homologic results of nucleotide
sequences from the patient and from animals in the same region, that a
reservoir for rabies in foxes was responsible for infectionref.
It was assumed that the fatal bite was carried out by a small nocturnal
carnivore which might have been mistaken by the patient for a rat or a
mouse, such as a stone-marten (Martes foina syriaca), or even a
small catref.
Rabies in palm rats (Rattus palmarum) was reported from Sri Lanka
and India. One incident was described in Slovakia in 1984. 2 epidemics
occurred in Voronej (Russia), the last in 2004ref.
On 24 Oct 1997, one of 2 domestic rabbits kept together within a petting
zoo in northern Israel was found dead with severe bite wounds. A small
hole was found in the fence, large enough for a mongoose or fox to enter.
3 weeks later, the 2nd rabbit died, after exhibiting signs of central nervous
system damage. Laboratory investigation confirmed rabies, presumably contracted
when bitten by the same unidentified rabid intruder. The rabies virus molecular
characterization revealed the same antigenic pattern demonstrated in wild
carnivores within the surrounding area. Over the last 10 years Tufts Wildlife
Clinic has seen a number of large native wild rodents (mostly woodchucks,
but also porcupines and beavers) with neurologic signs that have tested
positive for rabies. It has been our assumption that these species are
(a) because of their habits, fairly likely to come into contact with rabid
native carnivores (raccoons, skunks, etc.), and (b) large enough to survive
a bite wound and come down with the disease.
Other nontransmissible diseases : Mycoplasma
haemomuris(a.k.a. Haemobartonella muris) : a common parasite
transmitted by the mite Echinolaelaps echidninus found in the liver
cells of the laboratory rat, in which the infection is activated by splenectomy.
Rattus
rattus (black rat, house rat, roof rat) : Angiostrongylus
cantonensis,
Yersinia
pestis,
Seoul
virus,
SARS
coronavirus,
Novy's
rat disease (a viral disease discovered by Novy in his stock of experimental
rats), sialodacryoadenitis (severe inflammation of the salivary
and lacrimal glands in rats, caused by a coronavirus. Characteristics include
exophthalmos, facial swelling, and redness around the eyes. It is usually
self-limiting, but severe forms can lead to blindness).
Other nontransmissible diseases : Litomosoides
: a genus of filarial nematodes. L. carinii is found in the pleural
and peritoneal cavities of the cotton rat, Sigmodon hispidus, and
is widely used in studies of filariasis
squirrel pox virus : squirrel pox, or squirrel fibroma, is a viral
disease which produces multiple tumors on the skin of gray and fox squirrels.
It belongs to the pox group of viruses which produce rabbit fibromatosis,
rabbit myxomatosis, hare fibromatosis, and some deer fibromas. These tumors
are presumably all caused by a virus. Although the natural history of the
virus is not known, both Aedes aegypti and Anopheles quadrimaculatus
mosquitoes have transmitted it from squirrel to squirrel in the laboratory.
It is probably transmitted by insects in nature as well.The tumors develop
at the site where the insects feed on the animal. The tumors may be scattered
over all the body and range in size from a few mm to 25mm in diameter.
Metastasis to the lungs, liver, kidney, and lymph nodes has been reported.
In general, there are no obvious signs of illness
in naturally infected squirrels except for the presence of the tumors
over the skin. In severe cases, when vision is obstructed or the skin becomes
secondarily infected, the animal may be less active, weak, and eventually
die. The microscopic lesions of squirrel pox virus in the gray squirrel
are similar to those reported from Shope's rabbit fibroma virus in the
cottontail. Confirmation of the disease is either by histologic examination
of tissues for intracytoplasmic viral inclusion bodies or by virus isolation.
There is no known treatment; presumably a vaccine could be developed. But
it would not be logistically or economically feasible to treat free-living
wild animals. In cases where the disease is not severe, the lesions probably
regress and the animal recovers completelyref.
Squirrel pox virus has decimated red squirrel populations in the south
Cumbria area has jumped across the Scottish Border near Kershopefoot and
now threatens the UK stronghold of the species. Although grey squirrels
are immune to squirrel pox, they carry the virus and transmit it to the
native reds, sending populations into freefall. It causes skin ulcers,
lesions and scabs, with swelling and discharge around the eyes, mouth,
feet and genitalia of the reds. They then become increasingly lethargic,
losing weight rapidly. In all known cases, the virus is fatal in red squirrels
within 15 days. The Merseyside red squirrel population lives in Sefton,
an area stretching along the Lancashire coast from Southport down to Bootle.There
are thought to be < 600-1,000 red squirrels in the area. In 1995 a nearby
colony living around the town of Ormskirk was also affected by parapox,
and hardly any red squirrels are left there 75% of the 160,000 UK population
of red squirrels live in Scotland. The disease was first confirmed in grey
squirrels in East Anglia in the 1980s. Red squirrels were once widespread
throughout the British Isles, but now there are only about 160,000, most
in Scotland. The number in England isabout 30 000, most of those in the
north. There are around 10,000 on the Welsh island of Anglesey, and some
on the Isle of Wight and Brownsea Island in the south of England. Their
decline is blamed on disease, the loss and fragmentation of woodlands,
and competition by the greys, which now number > 2.5 million. They can
exploit deciduous woodlands better than the reds, and their breeding prospects
and adult survival rates are better there. It is believed that where grey
squirrels are carrying antibodies to this virus that they replace red squirrels
20 times faster than they would do normally have been the result of death
caused by infection with a parapoxvirusrelated to orf virus. Orf (contagious
ecthyma) is a universally-spread disease, prevalent in all sheep-raising
countries, which causes proliferative lesions on the skin of sheep, goats
and humans. It poses a major health and welfare problem in sheep, particularly
in neonatal lambs and nursing ewes and leads to significant economic losses
for the farmer. The orf virus is an epitheliotropic double-stranded DNA
poxvirus of the genus Parapoxvirus (PPV) which also includes the closely
related bovine papular stomatitis virus, pseudocowpox virus and a PPV that
infects deer. Tentative members of the genus include a sealpox virus and
viruses that infect red squirrels and camels. Research into the PPV disease
in UK squirrels has been undertaken by researchers of the Moredun foundation.
The initial studies were summarised by Colin McInnesref:
"An assay which measures antibody to the virus revealed that 61% of apparently
healthy grey squirrels have been exposed to the virus. In contrast, only
3% of red squirrels were found to have antibody to the virus, with 75%
of these animals showing clinical signs of squirrel poxvirus-associated
disease. These findings are consistent with the suggestion that the virus
causes little or no disease in the grey squirrels, but is highly pathogenic
for the reds. In addition, we found an apparent correlation between the
geographical distribution of grey squirrels with antibody to the virus
and the locations where squirrelpoxvirus disease is known to, or thought
to, have occurred, further supporting the hypothesis that the grey squirrel
may act as a reservoir host for the virus. Future studies at the Moredun
will concentrate on the characterisation of the virus itself". The said
article includes a map pertaining to the distribution of the disease in
the UK. Moredun Research Institute identified several immunodominant orf
virus antigens by monoclonal antibodies. Reportedly, these Mabs can be
used to differentiate different parapoxviruses from sheep, cattle, a seal
and a red squirrelref.
Instructions for the collection and dispatch of samples from sick squirrels
for laboratory investigations, published by the "Red Squirrels In South
Scotland Project"ref
infection in hamsters (and in rodents in general) are highly exceptional.
Rodents in general do not develop rabies because they do not survive the
effects of the bite from the rabid dog or cat that gave it to them. Small
rodents (such as squirrels, rats, mice, hamsters, guinea pigs, gerbils,
and chipmunks) and lagomorphs (such as rabbits and hares) are almost never
found to be infected with rabies and have not been known to cause rabies
among humans in the United States. Bites by these animals are usually not
considered a risk of rabies, unless the animal was sick or behaving in
any unusual manner, and rabies is widespread in your area. However, from
1985 through 1994, woodchucks accounted for 86 percent of the 368 cases
of rabies among rodents reported to CDC. Woodchucks or groundhogs (Marmota
monax) are the only rodents that may be frequently submitted to state
health departments because of a suspicion of rabies. In all cases involving
rodents, the state or local health department should be consulted before
a decision is made to initiate post exposure prophylaxis (PEP). Refraining
from PEP of persons allegedly bitten by rodents might lead to tragic consequences,
as shown, for example, in a 1996 case in which a 20 year old man became
ill 5 weeks after being bitten while asleep outdoors in Northern Israel
by an unidentified small animal, which, according to his description, was
a rat or a mouse. Since injuries by these rodents do not require antirabies
treatment, no antirabies PEP was given. The patient subsequently died of
rabiesref.
Later, it was concluded, on the basis of homologic results of nucleotide
sequences from the patient and from animals in the same region, that a
reservoir for rabies in foxes was responsible for infectionref.
It was assumed that the fatal bite was carried out by a small nocturnal
carnivore which might have been mistaken by the patient for a rat or a
mouse, such as a stone-marten (Martes foina syriaca), or even a
small catref.
Rabies in palm rats (Rattus palmarum) was reported from Sri Lanka
and India. One incident was described in Slovakia in 1984. 2 epidemics
occurred in Voronej (Russia), the last in 2004ref.
On 24 Oct 1997, one of 2 domestic rabbits kept together within a petting
zoo in northern Israel was found dead with severe bite wounds. A small
hole was found in the fence, large enough for a mongoose or fox to enter.
3 weeks later, the 2nd rabbit died, after exhibiting signs of central nervous
system damage. Laboratory investigation confirmed rabies, presumably contracted
when bitten by the same unidentified rabid intruder. The rabies virus molecular
characterization revealed the same antigenic pattern demonstrated in wild
carnivores within the surrounding area. Over the last 10 years Tufts Wildlife
Clinic has seen a number of large native wild rodents (mostly woodchucks,
but also porcupines and beavers) with neurologic signs that have tested
positive for rabies. It has been our assumption that these species are
(a) because of their habits, fairly likely to come into contact with rabid
native carnivores (raccoons, skunks, etc.), and (b) large enough to survive
a bite wound and come down with the disease.
