By Dr Andrew Tucker, Charles Street Veterinary Consultancy
What is Leptospirosis?
Irritation of the stomach lining can result in thickening of this Leptospira is a spiral bacteria occurring in pigs worldwide. There are nine different species of Leptospira and a particular pig or particular farm can have a combination of species present. Leptospira infection can be via ingestion or through abrasions. Infection can also be across the placenta or via the venereal route.
The bacteria then multiply causing a septicaemia which can produce clinical signs. Leptospira are known to cause liver and kidney damage and are normally limited by the pig’s immune system within 7-10 days after infection. The pregnant uterus can also be infected, resulting in foetal invasion and possible abortion 10-28 days after infection. Leptospira can also infect the central nervous system resulting in meningitis.
Leptospira can be shed in the urine for months after clinical recovery and hence it is via urine that Leptospira is most commonly spread. This can be from both infected and carrier animals. Rat infestation is a common source of infection however other mammals like dogs have also been shown to be the source. Leptospira can live up to thirty days in water so urine contaminated water is a big risk.
How do you know if it’s on your farm?
Three main clinical syndromes are associated with Leptospira infection in pigs.
• Subclinical infection where Leptospira is present in the herd but clinical signs are rarely seen.
• Acute/subacute infection. The first clinical sign is fever which results in dull pigs and decreased appetite. Yellow discolouration and nervous signs like tremor or weakness can also be seen. Mortality can be very high.
• Reproductive disorders. Not only abortions but also stillborn and neonatal mortality can be seen. In this case sows often have fever, decreased milk and a yellow discolouration. Increased incidence of mummies and returns to service are also typically seen with Leptospira infection.
Clinical signs and post mortem findings may suggest the presence of Leptospira. Various laboratory techniques can confirm the presence of Leptospira or specific antibodies to it.
How do you treat or prevent it? Various antibiotics are effective against Leptospira infection.
Control is normally obtained via vaccination of uninfected sows prior to insemination with killed vaccines. Hygiene and rodent control are vital parts of an effective Leptospira control plan.
Pig Diseases – D.J. Taylor; Diseases of Swine – Straw, Zimmerman, D’Allaire, Taylor