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Spring is finally in the air and many of you will be getting ready for turnout! This means its prime time to give your animals a leptospirosis booster.
Leptospira is a significant problem in UK cattle. There are many different bacteria strains, the most important for us being L. hardjo, for which cattle are the maintenance host. After infection, animals can carry the bacteria in their kidneys for months, sometimes years, excreting leptospires in their urine and acting as a reservoir of infection for other cattle.
How do animals become infected?
Infection arises from infected urine or products of abortion. Spring and summer, when cattle are out at pasture, are the highest risk periods. Moist spring grass is a favourable environment for the survival of leptospires outside the host. But they are sensitive to drying, acidic conditions, direct sunlight and extremes of temperature.
The following factors increase the risk of herds becoming infected:
- Buying in infected stock
- Co-grazing with sheep, which can carry and excrete L. hardjo
- Drinking from natural watercourses, which may be contaminated upstream
- From bulls – L. hardjo can colonize and persist in the genital tract of infected bulls and cows
What are the signs of infection?
While there may be no signs at all, a sudden milk drop often occurs 2-7 days after infection in lactating cattle. The udder becomes soft and flabby and may have blood-tinged milk. Abortions can occur up to 12 weeks after infection and the initial illness. Leptospirosis may also cause stillbirths or weak calves and chronic infertility. Sometimes there can be an abortion storm with large numbers of animals being affected. Occasionally severe acute disease causing fever, haemolytic
anaemia, jaundice, meningitis and death occurs, especially in young stock infected with other leptospirosis types (e.g. that commonly carried by rats).
It is also worth remembering that leptospirosis can be transmitted to humans, and causes a severe flu-like illness. This occurs following contact with infected urine or abortion material. Take great care if you suspect a problem on your farm and contact your doctor if you’re concerned you’ve been infected. Since not all doctors have diseases transmitted from animals at the top of their diagnosis list, specifically mention leptospirosis and make sure they know you are a farmer.
Leptospirosis can be readily diagnosed by regular bulk milk screening of dairy herds and blood testing in beef herds. Diagnosis can also bemade from the placenta and foetus from abortions.
Urine can be used to identify infected animals.
If you do not yet know the status of your herd, we would strongly recommend finding out. This will enable a suitable plan to be put in place to protect your herd.
This requires a combination of strategies to reduce the risk of infection coming onto the farm. Strategic antibiotic treatment for infected animals or during quarantine for bought-in animals, and protection of the herd by vaccination.
Fencing off any rivers or streams that are not required as a water source is advisable. In a herd with no evidence of a previous infection, all replacements should be isolated for at least 3-4 weeks and then tested for evidence of infection or exposure, and/or treated with streptomycin antibiotic on two occasions 10-14 days apart before entry into the herd. See your routine vet for advice on this and on the best policy for your herd in terms of monitoring, prevention and treatment.
If leptospirosis is diagnosed, or your herd is at high risk of infection, then vaccination provides good control. After the initial primary course, annual boosters need to be given every spring as this is the peak time for transmission of the disease. Vaccination should prevent urine shedding following exposure and will help protect against milk drop and abortion. During an outbreak, animals can also be treated with antibiotics to help reduce spread through the herd, but do speak to your vet first.
If you’re worried or would like to speak to a vet for more information, contact us