Goat disease jumps species in NZ for first time

Discovery of a cross-species transmission of a goat disease to cattle on Waikato farms has not only puzzled scientists but raised concerns about the reactions of trading partners.

The mycoplasma disease -- found in goats in many other countries -- been confirmed in New Zealand goats for the first time, and has also infected Waikato dairy calves in its first recorded occurrence in cattle anywhere in the world.

The organism -- mycoplasma mycoides subspecies mycoides (large colony type) -- causes polyarthritis or painful swelling of joints in goats, and has been a chronic problem in Californian milking flocks.

Mycoplasmas are small micro-organisms which differ from bacteria in that they do not have a cell wall.

The novel cross-species infection of cattle could make the outbreak of the goat disease a complicated trade problem if customer countries mistake it for a different mycoplasma with an almost identical name that causes a hugely contagious cattle disease.

A biosecurity official, Matthew Stone, of Wellington, said it was important that trading partners overseas did not mistake the unusual occurrence of the disease in New Zealand for other mycoplasmas which were more serious causes of disease in livestock, with significant international trade implications.

"One of the most important of these is mycoplasma mycoides subspecies mycoides (small colony), the cause of contagious bovine pleuro-pneumonia," he said. Despite the similarity in name, the infections of "large colony" and "small colony" M mycoides were "quite distinct".

The "small colony" organism had never been found in New Zealand livestock, he said. It causes contagious bovine pleuro-pneumonia (CBPP) which can be spread by coughing cattle and has been known to kill hundreds of thousands of animals in a couple of years.

But other livestock mycoplasma occur around the world with little impact, which Dr Stone said had made accurate identification of the organism in the New Zealand outbreak essential.

Today eight Waikato and South Canterbury farms are under movement restrictions to stop the spread of the disease.

It is thought to have been spread to the cattle after a Waikato dairy company unwittingly sold a tanker load of infected milk to a big calf rearer.

The "restricted" farms include a Waikato dairy farm producing milk from both goats and cows, two other goat farms, and four other dairy farms -- including the calf-rearer -- and a dairy farm in South Canterbury. Some of the farms are big dairy operations milking more than 1000 cows.

Dr Stone said 34 cases of the organism in goat kids and 39 cases in calves had occurred in the Waikato and six kids and 10 calves had died or been put down.

It was not yet known how the disease had arisen on the goat farm, but it had been reported to have occurred in New Zealand once before. It was reported in a single goat in the 1970s, but there are not records documenting the case.

-NZPA