Agent/cause
Caused by organisms collectively referred to as Leptospira Hardjo (Leptospira borgspetersenii serovar Hardjo and Leptospira interrogans serovar Hardjo).
Disease
- Milk drop.
- Infertility and abortion (usually during the second half of pregnancy).
- Birth of weak calves with a poor survival rate.
- L. Hardjo localises in the kidneys and the male and female genital tracts after infection and is shed in the urine. Some animals excrete it continuously for a short time and then stop; others shed either continuously or intermittently for life.
Introduction and spread
- Usually introduced by the purchase of infected cattle.
- Infection spread by contact with infected urine, infected bulls, sheep or contaminated water or pasture.
Impact
- Losses due to disease in cattle.
- Risk of infection in humans, with flu-like symptoms and severe headaches. Dairymen in the parlour are at particular risk and herd owners should be aware of their responsibilities under the Control of Substances Hazardous to Health (COSHH) regulations.
Control programme
- Testing programme using blood and milk samples to identify and remove potential carrier cattle. Screening and eradication
- Appropriate biosecurity to avoid reintroduction. Note that not all carrier cattle will be seropositive at the time of testing. As a result, testing of cattle in quarantine cannot guarantee that they are free of infection. It is recommended that all cattle being added to member herds should be treated twice with dihydrostreptomycin (25mg/kg) at a 14 day interval, or long-acting amoxycillin (15mg/kg) 48 hours apart (ensuring that the correct milk withdrawal times are observed) to further minimize the risk of introducing carrier animals.
- Culling, vaccination and antibiotic treatment can all play a role in eradicating infection from herds.