Leptospirosis

Leptospirosis

This disease can affect a wide variety of livestock, including deer. It primarily affects the kidneys, in some cases causing death. It can also cause weight loss and abortion. As it is transferable to humans it is known as a zoonosis disease. The most common strains of Leptospira in New Zealand (NZ) are Hardjo-bovis, Pomona and Copenhageni. Surveys of farmed deer in NZ suggest that infection with Hardjo-bovis is widespread. However this strain has a lesser affect on deer production than the Pomona strain.

How does the problem spread?
Carrier animals shed Leptospires onto pasture and into water when they urinate. Other animals become infected by getting infected urine or infected water onto cuts, abrasions or through the eyes, nose and mouth membranes. Leptospires need wet environments to survive.

What are the symptoms?
It can be difficult to diagnose. Deer may be listless and pass red urine (known as redwater).

Effect on deer production
The Pomona strain has been shown to cause abortions, reduce weaning percentages and cause death in weaners. Deer infected with the Hardjo-bovis strain are likely to have minimal production losses, compared to the Pomona strain. In one case a Manawatu deer farm reproductive efficiency increased from 90% to 98% following vaccination for Leptospirosis.

If the disease is transfered to the farmer or other farm workers, they are likely to requrie considerable time of work to recover. This can have a huge negative effect on the standard of farm management.

Diagnosis
The first sign of a problem is usually a dead animal. An autopsy should be done to confirm if it is caused by leptospirosis. Indications of infection are swollen kidneys, internal bleeding and jaundice. Slaughter plants will notify the farmer if white spots on deer kidneys are found, a sign that leptospirosis may be present.

To confirm if live deer are infected, blood and/or urine samples and then examination or culture should identify the disease. In the sub-clinical stage antibodies are produced which can be detected by an ELISA test. Consulting a veterinarian is the first step.

Control and treatment

  • Treatment of infected deer with antibiotics is the first step. In the early stages of an outbreak it may be beneficial to treat all deer that have been in contact with the affected animal. Infected deer that are chronic carriers (i.e. shedding the disease) can be cured by treatment with antibiotics.
  • Vaccination will prevent infection but not cure infection if it is already present. Either a two strain (Hardjo-bovis and Pomona) or three-strain (Hardjo-bovis, Pomona and Copenhageni) vaccine can be used. Veterinary advice can be used to select which is appropriate.
  • Deciding whether to vaccinate depends on the risks of infection. As an example, factors may include whether dairy cows/dairy grazers or beef cattle are run on the same farm as deer, history of past infections, farming downstream from farms known to have the disease present, or operating a trading rather than closed-herd.
  • Vaccination is considered to be a cost-effective option. Research shows a reproductive efficiency increase of only 1.3% would pay for vaccination costs.
  • Vaccination consists of a sensitiser and booster.

 The risk of infection can be reduced by:

  • buying only vaccinated livestock
  • treating or vaccinating all incoming animals
  • minimising runoff from neighbouring properties
  • running deer seperately, not with cattle
  • controlling rodents, pigs, wild deer and possums

Human health
This disease can be transfered from animals to humans. The symptoms of infection in humans in the first stage are flu-like chills, muscle pain, headaches and vomiting. The second stage can include jaundice and renal failure, diarrhoea and a rash. At its most agressive (Weil's syndrome) it can be fatal. Treatment includes high doses of antibiotics.

For more information and case studies of farmers and veterinarians infected with the disease, visit the Leptosure website. Leptosure is an iniative of the NZ Veterinary Association. 

Information on Leptospirosis is available in a convenient DINZ Deer Fact sheet (September 2015). Print off your own copy here >>