What the numbers are telling us
Tablelands Telegraph - June 2021
Dr Jess Bourke, District Veterinarian
Over the last two years, our vet and biosecurity teams have been working on a project that is a little different to what they usually do.
The teams set out to determine the risk posed by feral pigs to human and livestock health through the collection of samples from feral pigs trapped as part of routine pest management activities. The collected samples were tested to see if the pigs had been exposed to the diseases brucellosis and leptospirosis. Both diseases are zoonotic, which means they can be transmitted to humans.
Brucellosis in pigs is caused by bacteria called Brucella suis. It can be transmitted to dogs or humans though contact with body fluids and causes fever, lethargy and abortions in both species. Research has shown a prevalence of around 3% in feral pigs in northern NSW.
Leptospirosis is caused by one of many serovars (types) of the bacteria Leptospira. It can affect many species, including cattle and humans, causing fever/flu like signs in both species. In cattle, it can cause abortions and severe organ damage. In humans it can, in some cases, cause severe disease.
The project is continuing, but we've released some early results.
So far, we have tested over 200 pigs. Of these, none had evidence of exposure to Brucellosis. However, 25% of the feral pigs had been exposed to at least one Leptospira serovar, and 7% of them were actively shedding Leptospira bacteria at the time they were sampled.
This information allows us to shed some light on our original question. In our area, at this time, our findings suggest there is a very low risk of humans contracting Brucellosis via exposure to feral pigs. The risk of coming into contact with Leptospira bacteria appears to be a lot higher.
If you come into contact with feral pigs through work or recreation, it is important to take precautions to reduce the risk of transmission of Leptospira bacteria. NSW health recommends the following precautions for people who work with animals:
- Cover cuts and abrasions with a waterproof dressing
- Wear protective clothing (for example, gloves, eye shields or goggles, aprons and boots) when working with animals that could be infected, especially if there is a chance of contact with urine
- Wear gloves when handling cattle placentas or stillborn or aborted calves or carcasses
- Shower after work and wash and dry hands after handling potentially infected material
- Do not eat or smoke while handling animals that may be infected. Wash and dry hands before smoking or eating
To reduce the risk of Leptospirosis in cattle, a vaccine is available. Usually referred to as a "7in1", the product covers the same clostridial diseases as a "5in1" (such as tetanus and blackleg) plus two Leptospira serovars – Hardjo and Pomona.
