Aujeszky’s Disease
Pseudorabies
Other names |
Pseudorabies. PRV.
ADV. Suid herpesvirus (SHVI). Aujesky’s Disease |
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Causal agent |
Virus. Herpes DNA
virus. Enveloped |
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Age group |
All age groups |
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The disease is notifiable and a class B disease OIE. Several countries are free of Aujesky’s
Disease. |
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Clinical signs |
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Naive herds |
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Neonatal pigs |
Present with a range of severe
central nervous signs from fitting to
severe Incoordination. The piglets
may present as sitting like a dog due to posterior paralysis. Mortality
is high |
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Weaned pigs |
Central nervous signs may be reduced and an increase in respiratory signs |
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Respiratory diseases often associated with secondary
infections |
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Animals can waste and suffer ill thrift and are often
stunted |
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Growing pigs |
The CNS signs reduce and the respiratory signs
increase. The degree of respiratory disease
depends on secondary infections |
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Adults |
Reproductive signs predominate. Sows may abort and animals infected close to term give
birth to stillborn or weak piglets |
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On established herds |
May be few clinical signs |
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In other species |
The pig is the natural host for Pseudorabies |
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In other animals the disease either causes no problems or
is invariably fatal |
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In cats, rats and
mice the disease kills rapidly and this can
be important in diagnosis |
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Dogs present with a rabid signs, hence Pseudorabies |
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Cattle and sheep and rarely horses present with a mad-itch |
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Pseudorabies does not affect man |
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Dead finishing
pigs from an acute Pseudorabies outbreak |
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Weaned pig showing signs of severe depression. The animal also presented with pneumonia
and head pressing |
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Infectivity |
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Transmission within a herd is nose to nose, through mating
both natural and AI and transplacental |
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The virus can survive short periods in the air, up to 7
hours with the RH higher than 55% |
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The virus is rapidly inactivated when exposed to drying |
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Infection of wild animals also help to spread the disease |
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The disease can spread up to 2 km by air under the correct
conditions |
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Transmission can occur between trucks in transport and
tailgating of trucks should be avoided.
Also parking next to other pig trucks at service stations |
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Incubation period |
2 to 4 days |
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Post-mortem Lesions |
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Gross lesions are often absent or minimal |
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A serous to fibrinous rhinitis is common and a necrotic
tonsillitis. This does require
detailed examination of the head |
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Respiratory lesions of complicated pneumonia often present |
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The liver and spleen typically have yellow-white necrotic
foci (2-3 mm) |
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A necrotic placentitis and endometritis may be
observed. In aborted piglets there
may be necrotic lesions in the lungs, liver, spleen and tonsils |
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Post-mortem findings |
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Normal tonsils at the back of the pigs mouth |
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Necrotic debris in the nasal passageways and tonsils in a
pig with Pseudorabies |
Diagnosis |
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Clinical signs and virus isolation |
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Serology is of limited use in acute cases as it can take
7-10 days to produce antibodies |
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Diagnosis confused by maternal antibodies which may
persist for up to 4 months |
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Differential serology may be used to differentiate
vaccinated from field infected pigs |
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Treatment |
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None |
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Prevention |
Vaccination. Use
of a variety of modified live vaccines have been developed. The vaccine reduces
shedding and latency, but does not remove it. |
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Vaccines have been made from genetically modified
virus. These viruses have a variety
of nonessential proteins missing from their genome |
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In Northern Ireland, the vaccine uses a g1 deleted vaccine
strain. In other countries gIII, gX
and gp63 have been used. It is
important not to mix vaccine strains as they can recombine. The gX vaccine helped eliminate the
disease in the USA. |
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Control |
Good biosecurity. Purchase
only from Pseudorabies Free Herds. |
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Eradication |
Vaccination and elimination leads to Pseudorabies disease
free farms and areas |
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Depopulation followed by 30 day no pigs is recommended |
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Countrywide eradication programmes are successful but very
expensive. |
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Common differentials |
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Streptococcal diseases can produce similar necrotic
lesions in the liver and spleen.
Other causes of neurological, respiratory and reproductive diseases. |