leptospirosis

International Common Names

• English: leptospirosis in cattle; leptospirosis in sheep and goats; leptospirosis in swine; redwater of calves

Leptospira
Leptospira borgpetersenii
Leptospira borgpetersenii serovar hardjo
Leptospira hardjo
Leptospira interrogans
Leptospira kirschneri
Leptospira pomona

Leptospires are motile bacteria with hook-shaped ends, and internal flagella. They can be found in aquatic environments and are sensitive to desiccation. They are Gram-negative, do not stain well, but can be visualized using dark-field microscopy. Leptospires in tissues can be detected by silver impregnation and immunological staining techniques. Leptospirosis can affect all domestic animals and humans, and can vary in severity from mild infections of the urinary or genital tract to serious systemic disease. They are usually excreted in urine. Leptospirosis is a serious zoonotic disease.

Leptospira has several pathogenic species, including Leptospira kirschneri, Leptospira interrogans, Leptospira noguchii, Leptospira borgpetersenii, Leptospira santarosai and Leptospira weilii. These species are divided into over 250 different serovars in 23 different serogroups. Serologically similar leptospires can belong to different species; for example, serovar hardjo belongs to two species interrogans and borgpetersenii, because common surface antigens are shared by the two species which are genetically separate.

reproductive diseases of large ruminants
reproductive diseases of pigs
reproductive diseases of small ruminants
urinary tract and renal diseases of large ruminants
urinary tract and renal diseases of pigs
urinary tract and renal diseases of small ruminants

Disease in Cattle

Acute leptospirosis is seen mainly in calves. They show signs of fever, anorexia, pass red urine, are jaundiced and many die within 3 to 5 days. Survivors are usually unthrifty for the rest of their lives. Decreased reproductive performance can also indicate the presence of leptospirosis. Leptospirosis can cause stillbirths and abortions in late pregnancy. A cow may show no signs of illness before or after the abortion or stillbirth. Leptospirosis can decrease a calf drop by 40% or more during a bad epidemic. Mastitis may also be caused by leptospirosis. Cows show signs of fever and depression and go off their feed. The udder is flaccid in all four quarters and milk yield decreases. Milk is yellowish and may contain red flecks but usually returns to normal in 4 to 5 days, full production being restored after 2 to 3 weeks. Within a herd where there are cases of acute leptospiral mastitis, a large number of cows will show no signs of disease, but will have a fall in milk production. Several weeks later these cows may then abort.

Cattle that recover may become carriers and shed the organism in their urine. The organism can colonize the kidneys and cause nephritis and lead to excretion of the bacteria in urine (Yener and Keles, 2001; for further discussion, see Epidemiology section).

Leptospira pomona and L. hardjo can cause localized renal infections in young animals, leading to diarrhoea, anaemia, haemoglobinuria and abortion.The kidneys are swollen, with multi-focal petechial and ecchymotic haemorrhages that become pale with time. The liver may be swollen, with minute areas of focal necrosis. Petechial haemorrhages in other organs are seen in fulminating cases, however, in the more prevalent Leptospirahardjo infections, the lesions are primarily restricted to the kidneys.

Disease in Pigs

Leptospirosis in pigs causes reproductive losses in breeding herds throughout the world. Losses are due to abortion, stillbirths, weak piglets, and reduced fertility. Pigs are maintenance hosts for serovars of the pomona, australis and tarassovi serogroups, while strains of serogroups canicola, icterohaemorrhagiae, and grippotyphosa are often incidental infections. The most important serovar in pigs is pomona, which is found worldwide. Other serovars found in pigs are tarrassovi, bratislava, canicola, copenhageni, and icterohaemorrhagiae.

Cattle that recover from leptospirosis may become carriers and shed the organism in their urine. The organism can colonize the kidneys and cause nephritis and lead to excretion of the bacteria in urine (Yener and Keles, 2001). Cattle can shed leptospirosis in the urine for over 12 months.

If the urine is passed into an environment favourable to the bacteria, for example into moist, shaded areas with moderate temperatures, the bacteria can survive for a number of weeks. Survival in the environment can also be extended if the bacterium is picked up by carrier animals (rats, wild pigs, bandicoots, etc.) which can then re-infect the herd with their urine. Leptospires are able to penetrate the membranes of the mouth, nose, eyes and broken skin. Muddy areas around water troughs, water holes and dams are sites of infection. Pigs can act as long-term carriers of serovars pomona and tarassovi. Therefore leptospirosis is more likely on mixed dairy-pig properties or when feral pigs are present. As well as transmission via urine, sexual transmission is an important source of infection (Heinemann et al., 2000).

Leptospirosis presents an important zoonotic risk to people working closely with pigs.

Treatment includes antibiotic therapy. Administration of streptomycin, chlortetracycline or oxytetracycline in the early stages of infection reduces the number of leptospires in the tissues and the amount of excreted organisms.