Leptospirosis is one of the most common causes of abortion in cows in Ireland. It also can result in infertility and milk drop in cows.
Leptospirosis is a zoonosis – it can cause disease in humans. Farmers/farm-workers, abattoir workers and vets are the main groups at risk. The disease in man is usually acquired from contact with the urine, afterbirth or aborted foetus of an infected animal or with contaminated water. Clinical signs of the disease in humans are flu-like, with headaches and fever, occasionally progressing to meningitis.
There are two serovars of Leptospirosis commonly found in cattle in Ireland; Leptospira interrogans hardjo and Leptospira borgpetersenii hardjo. Leptavoid H is the only vaccine that is licensed to protect against both of these strains.
During primary infection, cattle shed leptospires in high levels in urine, milk and foetal fluids. This shedding can persist for a number of weeks. Recovered animals may intermittently shed leptospires in urine as many animals become renal carriers of the bacteria after infection. Sheep can also carry leptospires and can be a source of infection for cattle.
Clinical Signs of Leptospirosis
After the first phase of Leptospira infection in cattle, the bacteria localise in the kidneys and urinary tract. Early symptoms are usually mild and transient and are often not noticed. The most common clinical signs include;
- Milk drop – In cows, the first symptom is often a sudden decrease in milk yield.
- Abortions usually occur 6-12 weeks after the initial infection. Abortion rates range from up to 30% in herds not previously infected to 5% in herds where Leptospirosis is endemic. Diagnosis of
- leptospiral abortion is based on finding bacteria in the foetus or antibodies from blood samples from the cow.
- Infertility – The greatest effects of infection on fertility are low pregnancy rates and increased culling due to low fertility.
- Weak calves – infection in late pregnancy can result in the birth of weak calves that die within a few hours of birth.
- Prevention of Leptospirosis
A sudden milk drop is a common clinical sign of leptospirosis in cows
Leptospirosis is difficult to eradicate as some cows can become carriers. These cows shed the bacteria in their urine and are a source of infection for the rest of the herd. Leptospires can also survive for up to six weeks in wet soil and stagnant water or slow moving streams. Therefore the only practical way of preventing Leptospirosis is to vaccinate. Leptavoid H, the vaccine produced by MSD Animal Health carries a number of unique benefits as follows:
- Leptavoid-H is the only vaccine licensed to protect against both strains of Leptospira hardjo.
- Leptavoid-H can be used on the same day as Bovilis BVD
- Leptavoid-H is the only vaccine that is licensed to improve conception rates
Leptavoid-H – Proven to Increase Conception Rates
Vaccination with Leptavoid H is proven to increase conception rates where leptospirosis is diagnosed as a cause of infertility. In split herd trials, cows vaccinated with Leptavoid H had a 20% higher conception rate than cows in unvaccinated herds. The first service conception rate in the unvaccinated group was 31% and in the group vaccinated with Leptavoid it was 51%. The cows were examined for BVD and IBR and trace element deficiencies and leptospirosis was found to be the sole cause of infertility.
% increase in conception rate
Timing of Vaccination
It is essential to vaccinate heifers before their first pregnancy. To prevent infertility and abortion, heifers should be vaccinated with a primary course completed at least two weeks before turnout (2 injections 4-6 weeks apart).Cows should receive their annual booster in spring two weeks before turnout to grass.