Leptospirosis
Forty years ago, leptospirosis was one of the most common zoonoses in New Zealand, with over 400 human cases reported each year, mainly among dairy farm workers.
Since then, widespread vaccination of dairy cattle and pigs has significantly reduced the number of cases, with fewer than 100 confirmed in most recent years. However, leptospirosis is still present on many farms and in wildlife, and it continues to pose a serious risk to farmers, meat workers, and others in close contact with livestock.
It’s estimated that meat workers in New Zealand handle between 5 and 25 leptospire-infected carcasses each day, mostly from sheep and deer. Lifestyle farmers are particularly at risk if they milk unvaccinated cows, work with pigs that haven’t been vaccinated, or come into contact with possums, which can carry the infection.
This article will give you an overview of the current situation in New Zealand, to help you understand the significance of lepto for you and your animals.
How does the disease spread?
Lepto bacteria can infect cattle, pigs, sheep, deer, possums, rats, mice, and dogs as well as humans.
An animal becomes infected when bacteria in urine from an infected animal enter its body, either through the mouth or eyes or through skin cuts.
Once in the body, the bacteria generally localise in the kidney. They multiply there and can be excreted in the urine for months or even years.
From the urine, the bacteria may infect other animals, and so the cycle of infection continues.
Water sources can be contaminated by bacteria in urine from livestock, rodents, and other wildlife.
What's its effect on livestock?
Leptospirosis affects different species in different ways:
Cattle
There are two main types of lepto in cattle. Leptospira pomona cause abortion in cows and redwater in calves. L. hardjo infection is more common but it doesn't cause serious disease.
Nowadays the risk of commercial dairy farmers being infected by cattle is low because most dairy farmers vaccinate their cows.
Lifestyle farmers are at risk if their cows are not vaccinated.
Pigs
There are two main types of lepto in pigs. Leptospira pomona and L. tarassovi both cause abortion in sows, and piglets may be stillborn or die within a few days.
Some pigs carry the bacteria in their body, and excrete the bacteria in their urine but don't show signs of disease.
Lifestyle farmers are at risk if their pigs are not vaccinated.
Deer
In deer, there have been occasional outbreaks of leptospirosis causing redwater in young deer and the occasional abortion in hinds.
Deer can pick up the infection from pigs or wildlife.
Dogs
Some types of leptospirosis cause severe liver and kidney disease in dogs, but this is uncommon in New Zealand nowadays.
Leptospirosis is not usually included in the range of diseases that routine vaccination protects against.
Vaccination
Vaccination remains the most effective defence against leptospirosis. In New Zealand, vaccination of cattle, pigs, sheep, deer, goats, and dogs is now widely recommended, ideally under veterinary guidance.
Almost all dairy herds and a large majority of sheep and beef farms now vaccinate annually against Leptospira hardjo and pomona to prevent kidney colonisation, urinary shedding, and reproductive disease.
New four-way Lepto vaccines are available, targeting additional strains such as Pacifica, and are being gradually adopted, especially on dairy farms.
Recommended vaccination schedule:
Livestock (cattle, sheep, deer, goats, pigs): First dose from 4 weeks of age, followed by a second dose 4 to 6 weeks later, with annual boosters.
Dogs and puppies: Vaccinate from around 6 weeks old, with a second dose 2 to 4 weeks later, and annual boosters depending on vet advice.
When vaccination is especially important:
For dairy cows and pigs, to prevent shedding and protect human handlers.
In herds grazing mixed species (e.g. deer, alpacas), so all at-risk animals receive protection.
In dogs that may encounter wildlife-contaminated water or livestock environments.
What should you do now?
Review your current vaccine schedule: Are livestock or dogs on a four-way Lepto vaccine? When were they last boosted?
Discuss with your vet: They can advise on local disease prevalence, suitable vaccines, and timing.
Record-keeping matters: Documenting vaccinations (who, when, which product) is essential for both disease control and compliance.
Humans
In humans, lepto causes severe flu-like symptoms and meningitis, liver and kidney disease that can last for up to 6 months.
Fortunately, treatment with antibiotics such as streptomycin is effective especially if begun early.
The bottom line
If you home-kill livestock or handle pigs or possums or hand-milk dairy cows:
Make sure your personal hygiene is good.
Wear rubber gloves when handling anything contaminated by urine.
Put plasters on any cuts on your exposed skin.
Get your pigs and dairy cows vaccinated.
In some areas, it might be wise to vaccinate your dogs, deer, and alpacas. Your vet will advise.
For more practical guidance on keeping your animals healthy and recognising disease risks early, take a look at our livestock courses. They’re designed specifically for lifestyle farmers and packed with useful, real-world advice.
