Leptospirosis

Leptospirosis is a disease caused by a bacterium that has affinity for kidneys and genital tracts. Can also cause reproductive problems.

Alternative names: Leptospira interrogans, Leptospira borgpetersenii, pomona, icterohaemorrhagiae, canicola, bratislava, serjoe, tarassovi

Leptospira are bacteria with a long and slender spiral shape, present in most mammalian species. Over 260 serotypes are known, usually called serovars, and some species cause cross-reactions. Each serotype has one or more hosts (usually only two or three) that multiply and keep the bacteria. A serotype can remain infective all its life in its host reservoir.

In pigs, the important leptospires includes 2 species and various serotypes. They are Leptospira interrogans (serotypes pomona, icterohaemorrhagiae, canicola, and Bratislava) and Leptospira borgpetersenii (serjoe and tarassovi serotypes). It can be infected by other serotypes from urine of other animals, for example L. canicola of dogs and L. hardjo from cows but infections are subclinical and usually do not cause disease. The pig is then a fortuitous host, it is to say, it does not perpetuate the infection and it is only responsible for a minimum dissemination. It is believed that some wild animals act as reservoir hosts.

Once these organisms are introduced into pig farms they become carriers and produce kidney infections and intermittent excretion of the organism in urine. The disease is rare in nursing piglets and infects only individual animals.

Remember that this disease is zoonotic.

Sows

In acute outbreaks:

• Loss of appetite.
• Fever.
• Depression.
• Abortions during late pregnancy.
• Stillbirths.
• Increment of mummified piglets.
• Increase of weak, nonviable piglets.
• Increment of premature piglets.
• Increment of stillbirths.
• Increment of returns in breeding sows.

Lactating piglets

• Not as frequent.
• Loss of appetite.
• Jaundice.
• Blood in urine.
• Seriously ill pigs die.

Nursery and fattening

• Acute jaundice.
• Hemorrhage.
• Sudden death.
• Pale animals.

The infection can enter the farm in one of the following three ways:

1. Introduction of infected gilts and boars.
2. The infection can be introduced into the farm by other animals; rats, mice and dogs that can serve as reservoirs of the infection.
3. The farm has been exposed to indirect sources of contamination, for example contaminated water, dirty floors that are poorly maintained allowing urine to accumulate. It is transmitted through urine.

It is not an easy task but it could be very useful to:

• Study the percentage of abortions, returns, stillbirths, weak piglets and at what age it takes place in sows and gilts.
• Take blood samples from suspect animals and repeat 2-3 weeks later.
• Vaccines produce low antibodies.
• Serology interpretation is complicated by variable cross reactivity between serovars.
• PCR testing of aborted fetuses or urine.
• Special bacterial culture can be done but is challenging and requires very long period of time (12-26 weeks).

• Critical to interrupt the infection cycles pig-to-pig or rodent/wildlife-to-pig.
• Give vaccines to the breeding herd at least once every three to six months with vaccines of multiple strains.
• Use potable, uncontaminated water or use chlorination.
• Avoid use of surface water sources if possible
• Antibiotics can be used to control clinical signs but will not eliminate infection and usually require long treatment periods.
• Aggressive rodent control programs.