Diseases

Learn More About a Disease

Leptospirosis

Leptospirosis is caused by a bacterium from the family Leptospiraceae from the genus Leptospira. Leptospira comprises a wide variety of species, the largest of which is Leptospira interrogans, which itself comprises at least 23 major serogroups, each of which then comprises a number of serovars (over 250 pathogenic serovars have been identified). For any given region, only a limited number of serovars are prevalent. Leptospires can infect a number of different animal species and humans. The serovars survive in reservoir species in which they cause few clinical signs. For example, the reservoir of the serovar Hardjo is cattle, while pigs, cattle and skunks may be reservoirs of the serovar Pomona.

Leptospires survive relatively easily outdoors, which encourages contamination. They do not multiply, but survive in water or muddy ground with slightly alkaline pH, very low acidity, and an absence of ultraviolet rays (in warm, moist, shady environments) for up to six months. They need fresh water to survive in this environment. Heat, frost, light, and the usual antiseptics quickly destroy them.1

Clinical Signs +

Clinical signs vary according to the serovar involved and the type of infection. The acute form is associated with L. canicola and L. icterohaemorrhagiae. Infected pigs have a fever of over 40°C, are listless and anorexic and develop diarrhea and, more rarely, jaundice accompanied by hemolysis.1

In North America, the two serovars most frequently isolated in pigs are L. pomona and L. bratislava. They primarily cause reproductive problems, including abortions, piglets that are weak at birth, and smaller litters. L. bratislava is also associated with infertility in sows. The subclinical phase is associated with serological evidence of infection, but without the clinical signs.

Transmission +

The infection is generally transmitted by contact with other pigs' urine. Rodents play a significant role in maintaining the disease in pig farms. Infected animals, even if they are not sick, may excrete the bacterium in their urine and infect a person or other animal.1

Diagnosis +

The most common diagnosis is through serology. Serological tests include agglutination tests, such as ELISA. Confirming the presence of the bacterium is more complex (immunofluorescence, immunoperoxidase), but makes diagnosis more certain.

Treatment +

To properly control the disease, it is crucial to interrupt transmission of the infection by infected pigs or other hosts to noninfected pigs. A combination of antibiotic treatment, vaccination, and herd management must be used to eliminate the disease in a herd.

The bacteriumis sensitive to many antimicrobial drugs, but antibiotic therapy does not always succeed in eliminating chronic carriers. Proper sanitation and vermin control may help to reduce the spread of the infection. Vaccination of breeding herds will reduce the prevalence of disease.

Consult your veterinarian before administering antibiotics and vaccines to animals.

Your veterinarian is the best person to talk to for recommendations that are right for your farm. 

REFERENCES:

1 Maladies d’élevage des porcs, 2nd Edition, Guy Pierre Martineau

2 Handbook of Pig Medicine, Peter Jackson & P. Cockcroft, Ed. Saunders, 2007