Leptospira borgpetersenii serovar hardjo type hardo-bovis

Hardjo-bovis

Leptospira borgpetersenii serovar hardjo type hardjo-bovis is a thin, spiral-shaped, tightly coiled spirochete. It is the most common cause of bovine leptospirosis in the U.S. In addition, hardjo-bovis is one of the more important of the most common serovars because cattle are maintenance hosts. Leptospires are transmitted to cattle via maintenance hosts and incidental 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 hardjo-bovis, the sole maintenance host is cattle. As such, only cattle transmit the bacteria, infecting each other and other animals (sheep and humans). Transmission can even occur in utero, resulting in maintenance host calves being born. Carrier animals—maintenance hosts—shed leptospires in urine, reproductive fluids and uterine discharges, thus contaminating pastures, drinking water and feed.

Incidental hosts do not carry the bacteria and are only infected for a short period. Once incidental hosts are removed from exposure to a maintenance host, the disease is not perpetuated.

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Etiology

Leptospira ingested by cattle from contaminated water enter the body through the mucous membranes of the nose, eyes, mouth or reproductive tract, or breaks in the skin. The organisms spread immediately from the entry site to the bloodstream and then potentially to all tissues.
The leptospires replicates within the body of the host then eventually pass from the body in urine, causing more infections—particularly if the urine contaminates water sources frequented by susceptible animals.
Infected urine is the major source of contamination and disease transmission. Infected cows that abort their fetuses can also excrete Leptospira from their genital tract.
Another source of infection is semen. An infected bull can carry the organisms and infect females.

Symptoms

Infection is in most cases clinically inapparent. Therefore, the symptoms may be in the form of delayed breeding, early embryonic death, infertility, abortions, weak calves and other economically devastating reproductive consequences.

Diagnosis

Diagnosis is difficult because most animals do not show clinical signs of the disease. The best way to determine if a herd is infected with hardjo-bovis is to test the herd. Laboratory tests show the presence of Leptospira antibodies in individual cow serum and Leptospira organisms in urine. (or tissues from aborted fetuses)

Treatment

Consult your veterinarian regarding treatment options for Leptospirosis.

Prevention
The following practices help lessen transmission of hardjo-bovis bacteria:
Clean and disinfect pens once occupied by infected animals.
Use pits rather than common manure alleys to prevent cross-contamination between pens by way of splashing urine.
Drain or fence low-lying or swampy areas.
Prevent animal access to stagnant water or runoff from animal pens.
Leptospira borgpetersenii serovar hardjo type hardjo-bovis can be prevented. Prevention requires vaccination before infection. For comprehensive protection against Leptospira use Spirovac^®, Spirovac^® L5 or Spirovac^® VL5* alone or incorporated into a complete viral respiratory and reproductive vaccination protocol with Bovi-Shield GOLD FP^® 5 L5 HB or Bovi-Shield GOLD FP^® 5 VL5 HB*.
Initial vaccination with Spirovac^®, Spirovac^® L5, or Spirovac^® VL5* is two doses given four to six weeks apart. Annual revaccination with a single dose is recommended.
*Vaccines containing VL5 fractions are not recommended for use in dairy cattle

Economic Impact

Leptospira borgpetersenii serovar hardjo type hardjo-bovis is one of the most important and costly contributors to reproductive loss in the beef and dairy industries.

Highlighted Product(s)

Spirovac^®

Spirovac^® L5

Spirovac^® VL5

Bovi-Shield GOLD FP^® 5 L5 HB

Bovi-Shield GOLD FP^® 5 VL5 HB.

*LABEL INDICATIONS: Do not use in pregnant cattle (abortions can result) unless they were vaccinated, according to label directions, with any BOVI-SHIELD GOLD FP or PREGGUARD GOLD FP vaccine prebreeding initially and within 12 months thereafter. Do not use in calves nursing pregnant cows unless their dams were vaccinated within the past 12 months as described above. To help ensure safety in pregnant cattle, heifers must receive at least 2 doses of any BOVI-SHIELD GOLD FP or PREGGUARD GOLD FP vaccine with the second dose administered approximately 30 days prebreeding.