Leptospirosis: A risk to your herd and your health

By Cara Sheridan, veterinary advisor with MSD Animal Health

Leptospirosis is one of the most common causes of abortion in cattle in Ireland. It is an endemic disease, meaning that the majority of herds test positive for it.

Leptospirosis is also a zoonosis – it can cause disease in humans. All those working with stock are potentially at risk. Clinical signs of the disease in humans are flu-like symptoms, with headaches and fever. This can occasionally progress to meningitis.

It can be acquired from contact with urine, afterbirth or the aborted foetus of an infected animal.

There are two serovars of leptospirosis commonly found in cattle in Ireland – Leptospira interrogans hardjo and Leptospira borgpetersenii hardjo.

Leptospirosis circulates in a herd by direct transmission from infected animals (new infections or carrier animals) or by indirect transmission through urine, birth fluids, milk, contaminated water, or other species – for example, sheep.

It’s very difficult to eradicate as some cows can become carriers. Leptospires can also survive for up to six weeks in wet soil and stagnant water or slow-moving streams.

Clinical signs of Leptospirosis

Early signs are usually mild and transient and therefore may go unnoticed.

The most common clinical signs include:

Milk drop – a sudden decrease in milk yield;
Abortions – usually occur six-to-12 weeks after the initial infection. Abortion rates may be up to 30% in a herd infected for the first time;
Infertility – low pregnancy rates and, therefore, 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.

Diagnosis of Leptospirosis

Diagnosis of the disease is based on blood sampling and looking for high antibody levels in affected animals.

However, this can prove difficult. Often, the infection is present six-to-12 weeks before clinical signs become apparent (e.g. low pregnancy rates picked up at scanning).

It can also be based on the culturing of urine samples. In addition, leptospiral abortion diagnosis is best based on the identification of bacteria in the foetus. Farmers are encouraged to speak to their vets about investigating leptospirosis in their herds.

Control of the disease:

Isolation of the sick cow and aborting cow;
Biosecurity – avoid the introduction of infected animals;
Quarantine until test negative;
Double fencing at perimeters;
Vaccination – the only practical way of controlling leptospirosis.

Timing of Vaccination

It is essential to vaccinate heifers before their first pregnancy. The primary vaccination course consists of two injections four-to-six weeks apart.

An annual booster before turnout and at least two weeks before breeding is required. It is a 2ml dose, given under the skin to all cattle greater than one month of age. The correct use and timing of the vaccinations are vital to their success. The manufacturer’s recommendations should always be read.

Why vaccinate with Leptavoid-H?

Leptavoid-H is the only vaccine licensed to protect against both strains of Leptospira hardjo;
Leptavoid-H is the only vaccine that is licensed to improve conception rates where leptospirosis has been diagnosed as a cause of infertility;
Leptavoid-H can be used on the same day as Bovilis BVD (to cattle greater than eight months of age).