Leptospirosis (Lepto) is a zoonotic disease that can be passed from infected cows to humans, usually through contact with urine, afterbirth or an aborted foetus.

Lepto is a bacterial disease that affects both humans and animals. It is caused by the bacteria genus Leptospira.

Clinical signs in humans start as flu-like symptoms. If left untreated, Lepto can lead to kidney damage, meningitis, liver failure, respiratory distress and even, death.


The two commonly found strains of Lepto found in Ireland are Leptospira interrogans hardjo  and Leptospira borgpetersenii hardjo.

Cattle usually contract the disease through contact with infected urine or products of an abortion.

Having an open herd is a risk, because an infected animal could be bought in and infect a number of other animals in the herd.

This could have a major financial impact on a herd.

The sharing of bulls is also a risk, with a bull easily spreading the disease between herds.

Sheep can excrete Lepto so mixed grazing of sheep and cattle can be a risk too.

Clinical signs

A drop in milk production is often the first symptom. This is often a sudden decrease in milk yield, but this can be mistaken for another issue such as changes in feed, lungworm, bovine viral diarrhoea (BVD) or infectious bovine rhinotracheitis (IBR).

Infertility can also be a sign there may be an outbreak of Lepto within the herd. This could lead to reduced pregnancy rates and increased culling within the herd.

Infection in late pregnancy can result in the birth of weak calves that die within a few hours of birth. This could be mistaken for iodine deficiency, which has similar symptoms.

Abortions in cows are often when an outbreak in detected. The rate of abortions within the herd can vary from 5% (where Lepto has been present in a herd for a number of years) to 30% (in herds not previously infected).

The products of an abortion should be sent away to a lab for analysis. Lepto bacteria can usually be found in the foetus or from blood samples taken from the cow.


The prevention of a Lepto outbreak requires a combination of herd management to reduce risk and a vaccination programme.

You should avoid the purchasing of animals without ensuring they have been vaccinated. Any unvaccinated animals should be placed in isolation until they have been vaccinated or cleared.

Ideally, you should vaccinated your heifers before they become pregnant. This usually involves two injections, four to six weeks apart, with an annual booster shot also required.