Leptospirosis
Other names |
In man infection with L.
icterohaemorrhagica is called Weil's Disease |
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Causal agent |
A very large family of bacteria present in all parts of
the world. They belong to the
spirochaete type of bacteria There are five serovars and groups which are important to
the pig: pomona, australis (bratislava) and tarassovi together with canicola,
icterohaemorrhagicae and grippotyphosa |
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L. pomona |
The most clinically important Leptosposis is L. pomona. However, L. pomona
is not present in all countries. |
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Age group |
Mainly the adults are affected with clinical signs. Note that non pig specific leptospira can
infect any age group. For example jaundice due to L. icterohaemorrhagica can affect weaners as well as adults |
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Clinical signs |
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Acute |
Anorexia, pyrexia and listlessness. Therefore very non-specific and tends to
only affect individuals, on majority of farms these signs are missed. |
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With L.
icterohaemorrhagica the animals can be very ill and jaundiced |
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Chronic |
Abortions, stillbirths an the birth of weak pigs and other vague reproductive problems
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Aborted piglets but note there are many causes of abortion
in the pig |
Interstitial nephritis – commonly associated the L. pomona | Normal and jaundiced pig – yellow. | |
Infectivity |
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The organism cannot withstand drying, but will live for a
long time in wet conditions. Rodents
can carry many leptospiral diseases |
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Post-mortem Lesions |
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Acute cases |
The pathological findings can be very limited |
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Chronic |
Mainly confined to the kidneys and consist of scattered
small grey foci of a focal interstitial nephritis. Note many other diseases can cause identical findings and
leptospira can be isolated from kidneys with no pathological damage |
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Diagnosis |
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Can be difficult |
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Serology |
Antibody positive titres can be very transient, lasting
less than a month. Many serological tests are inconclusive at 1/100 |
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Demonstration |
The demonstration of Leptospiras in tissues can be
achieved but is not easy |
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Culture |
Difficult and time consuming. Leptospira are also normal in healthy animals |
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Treatment |
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Individuals |
Streptomycin at 25mg/kg is effective |
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Group |
In-feed medication with 800g of chlortetracycline per
tonne of feed for 6 weeks. |
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Vaccines |
Vaccine only protective for 3 months. Vaccines are not available in all
coutries. |
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Control |
Rodent control and biosecurity |
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Manage wallows to allow the wallow to dry out during the
summer. Disinfect water supplies |
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Routine treatment of boars especially at AI studs |
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Common differentials |
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Other reproductive problems. Poor stockmanship and breeding routines |
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Zoonotic |
Various leptospiral species cause problems in humans. Some are potentially fatal. |
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