Risk factors of leptospirosis

LEPTOSPIROSIS is a common infection in dairy and beef herds. It is considered an important zoonotic infection (transmissible to humans).

Disease is spread most often during the spring and summer months while cattle are at pasture.

Disease is spread most often during the spring and summer months while cattle are at pasture.

• The two important types of Leptospir hardjo are Leptospira borgpetersenii serovar Hardjo and Leptospira interrogans serovar Hardjo

• Infection arises from contact with infected urine or the products of abortion

• Disease is spread most often during the spring and summer months while cattle are at pasture.

Economic implications

Economic losses result from:

• Infertility • Abortion

• Poor milk yield

Leptospirosis affects humans causing influenza-like symptoms with severe headaches but can be treated effectively. Pasteurisation destroys all leptospire organisms.

The important risk factors for leptospirosis are:

• Open herds • Using shared bulls

• Mixed grazing with sheep

• Shared grazing with common watercourses

The important risk factors for leptospirosis include shared grazing with common watercourses

The important risk factors for leptospirosis include shared grazing with common watercourses

Clinical signs

• Sudden drop in milk yield occurs two to seven days after infection of susceptible cows

• Udder becomes soft and flabby with colostrum-like secretions

• Some cows become lethargic, and stiff with a fever and reduced appetite

• Abortion may occur three to 12 weeks following infection

• Infection may also produce premature and weakly calves

Differential diagnoses

There are numerous causes of a marked drop in the bulk tank recording which your veterinary practitioner will consider including (large numbers of cows affected):

• sudden changes in feeding regimen/acidosis

• bovine virus diarrhoea infection (BVDV)

• lungworm infestation,

• infectious bovine rhinotracheitis (IBR),

• bovine respiratory syncytial virus (BRSV),

• influenza A.

• Salmonellosis

• Bluetongue

• Schmallenberg virus infection The common infectious causes of abortion include:

• Neospora caninum

• BVDV infection

• Salmonella spp.

• Bacillus licheniformis

• Campylobacter

Leptospirosis cannot be transmitted by artificial insemination.

Leptospirosis cannot be transmitted by artificial insemination.

Diagnosis

• Various tests detect antibodies to Leptospira Hardjo in blood samples and foetal fluids

• A bulk milk ELISA test is available

Treatment

A single intramuscular injection of streptomycin/dihydrostrepomycin at 25mg/kg will eliminate infection from most cattle.

Control/prevention

As a precautionary measure streptomycin is added to semen from bulls held at artificial insemination centres.

Control

• Reduce risk of infection:

• Open herds

• Using shared bulls

• Mixed grazing with sheep

• Shared grazing with common watercourses

• Strategic antibiotic treatment

• Vaccination

Herds with evidence of endemic infection indicated by herd screening or abortion serology should vaccinate with an annual booster. Replacement heifers should have completed their vaccination course before first service.

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