Scientists in Dunedin are developing a vaccine to help protect the country's wild possums against tuberculosis. Why? Because the possums transmit the disease to cattle and other livestock.
With an estimated 70 million possums in New Zealand, the introduced animal is a major pest. As well as destroying native plants and birds, many carry bovine tuberculosis, which the infected possums then pass on to cattle.
"So you have a sick possum walking across the pasture, it's shedding bacteria as it goes, and also if it's feeding in a hopper, and so when the cattle come back onto that pasture or use that food source, they then pick up the TB," says Dr Dan Tompkins, Landcare Research.
Scientists at Landcare Research have gone to the root of the problem for farmers, developing a vaccine which protects possums from catching TB in the first place.
"You can control it in the cattle, but the minute you stop or let your guard down it would come back in again from the wildlife," says Dr Tompkins.
Despite an almost 50-year campaign to eradicate TB from the country's cattle population, the problem remains. Infected possums cop much of the blame, being found in over a quarter of the country.
Shooting or poisoning possums with 1080 often is not possible in urban areas or around waterways.
Researchers have been conducting field trials on the TB vaccine near wellington. The vaccine has a unique fat coating - developed at Otago University - ensuring it is fully absorbed by the animal.
Tagged animals were rechecked for TB symptoms every two months. The vaccine proved 90 percent effective.
"So rather than having to catch possums and inject them all - which of course would not be possible - this enables us to have an oral vaccine, which we can disseminate either in hoppers or from helicopters," says Dr Tompkins.
Researchers admit the vaccine is no magic bullet for possum problems, but along with new tools like fertility control, it could reduce the amount of 1080 used and make possum control more acceptable.
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