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Leptospira icterohaemorrhagiae

Leptospira icterohaemorrhagiae

Leptospira icterohaemorrhagiae is a thin, spiral-shaped Leptospira bacterium. Leptospires are transmitted to cattle via maintenance hosts. Maintenance hosts are a constant source of infection and typically do not show clinical signs. As silent-carrier animals, they maintain the bacteria and transmit leptospires to other animals. Transmission is efficient, with incidence of infection relatively high. Maintenance hosts can be carriers for months, years or even a lifetime.

In the case of L. icterohaemorrhagiae, the maintenance host is the rat. As such, only rats transmit the bacteria, infecting each other and other animals (cattle and pigs). Cattle are incidental hosts and do not carry the bacteria and are only infected for a short period. Once incidental hosts are removed from exposure to a maintenance host (infected rats), the disease is not perpetuated.

Leptospirosis is one of the most important and costly contributors to reproductive loss in the beef and dairy industries.

The most common cause of bovine leptospirosis in the U.S. is Leptospira borgpetersenii serovar Hardjo type hardjo-bovis. Although, Leptospira icterohaemorrhagiae is not the most common cause of bovine leptospirosis, it is important to control and help prevent the disease.

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  • Infected urine is the major source of contamination and disease transmission.  Infected cows that abort their fetuses can excrete Leptospira from their genital tract.  Leptospira ingested by cattle from contaminated water enter the body through the mucous membranes of the oral-nasal cavity. In susceptible cattle, the leptospires infect the bloodstream and tissues, localizing in specific organs, namely the kidneys, uterus, liver and udder. The primary leptospirosis lesion is damage to the walls of small blood vessels, resulting in necrosis of kidney tubules and in liver damage. An adequate immune response will help eliminate Leptospira from the bloodstream and tissues, although long-lasting tissue damage may occur. Some leptospires may survive in sequestered body sites that are inaccessible to circulating antibodies, resulting in a chronic carrier state with Leptospira shed intermittently in the urine, but with no clinical signs of disease.

  •  Infection is in most cases clinically inapparent; however, depending on the virulence and size of the challenge dose, clinical signs may appear, including a high fever, inappetance, hemoglobinuria (bloody urine) and depression.  In utero infection results in infertility, abortions, stillbirths, or weak calves, often in multiple cows in the herd. The reproductive consequences of leptospirosis may occur weeks or months after clinical signs of acute infection, making diagnosis difficult.

  • Diagnosis is difficult because most animals do not show clinical signs of Leptospirosis.  Laboratory tests show the presence of Leptospira antibodies in bulk tank milk samples and individual cow serum and urine.

  • Contact your veterinarian regarding treatment options for Leptospirosis.

  • Leptospirosis can be controlled by eliminating swampy areas from the premises, and restricting the access of cattle to stagnant water and runoff from animal pens.  Rats can be vectors for Leptospira. Therefore, control of these animals will help minimize disease transmission. Because leptospirosis is widespread in the U.S. cattle population, all cattle used for breeding purposes should be vaccinated for the most common Leptospira serovars, including  L. icterohaemorrhagiae. There is little or no cross-protection among Leptospira serovars. Therefore, it is important to vaccinate all susceptible cattle with Spirovac® L5 or Spirovac VL5 prior to breeding to help preempt reproductive loss associated with leptospirosis, including Leptospira borgpetersenii.  Vaccination with Bovi-Shield GOLD FP® 5 L5 HB or Bovi-Shield GOLD FP® 5 VL5 HB will also help protect cattle against the most common Leptospira serovars, including Hardjo-bovis, grippotyphosa, icterohaemorrhagiae, pomona, and canicola, plus bovine respiratory disease (BRD).

  • Leptospirosis is one of the most important and costly contributors to reproductive loss in the beef and dairy industries.