Rabies
DISEASE NAME- Rabies
ANIMALS AFFECTED- All warm blooded animals. Dog, opossum, skunks, wolves, foxes,
monkeys etc.
ABOUT DISEASE- An acute, viral encephalitis that affects all warm blooded animals. The
mortality rate is close to 100%. Although rabies occurs throughout the world, a few
countries are free of the disease due to successful eradication programs, or by virtue of
there island status or enforcing rigorous quarantine regulations.
Rabies virus replicates by budding from the host cell membranes, and viral nucleocapsid
develops in the cytoplasm. Complete viral particles may be formed at the cell surface, but,
more commonly, they from intracytoplasmic membranes. Free virus particles infect new or
adjacent cells by fusing their envelopes with the host cell membrane, which allows direct
entry of viral genetic material.
Rabies is found in two forms ‘furious’ and ‘dumb’.
CAUSE- Rabies virus is the prototype of the genus Lyssavirus in the family Rhabdoviridae.
The agents are enveloped bullet shaped RNA viryses that usually measure 75-180nm. The
single strand of non- segmented RNA (negative sense) encodes five structural proteins, a
nucleocapsid (N) protein, a phosphoprotein (P), a matrix (M) protein, a glycoprotein (G),
and a RNA dependent RNA polymerase (L). These viruses have been isolates worldwide
and were originally considered to belong to one common antigenic type. However,
techiques using monoclonal antibodies (MABS) produced against viral proteins and gene
sequencing techniques have provided evidence for antigenic and genetic differences
(variants) among various isolates from major wild life and domestic animal hosts within a
given geographic region. Of the 4 lyssavirus serotypes currently recognized, serotype 1 is
responsible for classical terrestrial animal rabies. Serotypes 2,3 and 4 are rabies related
viruses that have antigenic and epidemiological differences from rabies proper. Rabies
virus recently identified in European bats are currently classified as serotype 4.
Symptoms- Rabid animals often:
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Are fully or partially paralyzed
Experience a loss of appetite
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Exhibit strange behaviors, such as snapping at the air or turning in circles
Are nocturnal animals who wander during the day -- or diurnal animals who start
going out at night
Drool excessively
Are wild animals who show no fear of humans
Exhibit symptoms of pica (eating substances that aren't food, such as rocks, dirt or
wood)
Have sporadic changes in mood or behavior
Appear to be restless or aggressive
Are disoriented.
Acquire a change in voice (a change in the pitch and tone of the dog's bark, for
example)
CONTROL AND MANAGEMENTPREEXPOSURE VACCINATION AND MANAGEMENT: Parenteral animal rabies vaccines
should be administered only by or under the direct supervision of a licensed veterinarian
on premises. Rabies vaccinations may also be administered under the supervision of a
licensed veterinarian to animals held in animal control shelters before release. The
veterinarian signing a rabies vaccination certificate must ensure that the person
administering vaccine is identified on the certificate and is appropriately trained in vaccine
storage, handling, administration, and in the management of adverse events. This practice
assures that a qualified and responsible person can be held accountable for properly
vaccinating the animal. Within
28 days after initial vaccination, a peak rabies virus antibody titer is reached, and the
animal can be considered immunized (29,31-33). An animal is currently vaccinated and is
considered immunized if the initial vaccination was administered at least 28 days
previously or booster vaccinations have been administered in accordance with this
compendium.
Regardless of the age of the animal at initial vaccination, a booster vaccination should be
administered 1 year later (see Parts II and III for vaccines and procedures). No laboratory
or epidemiologic data exist to support the annual or biennial administration of 3- or 4-year
vaccines after the initial series. Because a rapid anamnestic response is expected, an animal
is considered currently vaccinated immediately after a booster vaccination (34).
a) DOGS, CATS AND FERRETS
All dogs, cats, and ferrets should be vaccinated against rabies and revaccinated. If a
previously vaccinated animal is overdue for a booster, it should be revaccinated.
Immediately after the booster, the animal is considered currently vaccinated and should be
placed on a booster schedule, depending on the labeled duration of the vaccine used.
b) LIVESTOCK
All horses should be vaccinated against rabies. Livestock, including species for which
licensed vaccines are not available, that have frequent contact with humans (e.g., in petting
zoos,
fairs, and other public exhibitions) should be vaccinated against rabies. Consideration
should also be given to vaccinating livestock that are particularly valuable.
c) STRAY ANIMALS
Stray dogs, cats, and ferrets should be removed from the community. Local health
departments and animal control officials can enforce the removal of strays more effectively
if owned animals are required to have identification and are confined or kept on leash.
Occurrence- The predominant animal species in which rabies is maintained varies in
different parts of the world. Dog rabies predominates in Africa, Asia, Latin America, and the
Middle East. In North America and Europe, where rabies has been effectively controlled,
the disease is maintained in wild life species. In North America, skunk, raccoon, and fox
rabies are each found in fairly distinct geographic regions, although some overlap in
distribution occurs. These distribution differences can also be detected as differences in
viral strains by monoclonal antibody typing. Bat in rabies is distributed throughout the
U.S.A., and monoclonal antibody typing can differentiate rabies viruses of bat origin from
those of terrestrial wildlife origin. In Europe fox rabies predominates. The vampire bat s an
important reservoir in Mexico, Central and South America, and parts of the Carribean , and
is the source of outbreak in cattle. Other wildlife species may species may play an
important role in the maintenance of rabies in certain areas, including mongoose in the
Carribean and Southern Africa, jackals in certain parts of Africa, and wolves in parts of
Northern Europe.
Source - Merck’s Veterinary Manual