A tropical disease - virtually unknown in Switzerland - is causing alarm among farmers and veterinary experts, after it struck a cattle herd in south eastern Switzerland.

Authorities have said the entire herd of 300 cows in canton Graubünden should be put down, although the owner is reportedly battling to save some of the animals.

There are now concerns that the disease could spread, because some of the cows from the herd were sold on to other farmers before the tick-borne infection, known as anaplasmosis, was diagnosed.

"We should assume that some of the cows that were sold are carrying this disease and if they are then bitten by ticks, then it could spread," said Ueli Braun, professor of ruminants at the University of Zurich. "But personally, I'd say the danger was small.

"It'll be at least a week before we know whether other herds have been contaminated," he told swissinfo. "They are currently being tested."

Treatment

Anaplasmosis, which is most common in tropical countries, can be treated by carrying out a blood transfusion on the infected animals.

"We've successfully treated two of the infected cows," said Braun. "But it's not possible to treat such a large number."

The disease affects the blood system of cattle, causing severe shortages of red blood cells and leading to symptoms similar to anaemia, including weakness and fever.

Vaccine

In regions such as Latin America and Africa, where the disease is widespread, animals have become immune.

"In Latin America, cattle are rendered immune by being repeatedly bitten by ticks, a method which acts like a natural vaccine," Marcio Folly, a veterinarian with the laboratory of agricultural products in canton Fribourg, told swissinfo. "Or they are vaccinated directly with the bacteria."

However, no such treatment is available in Switzerland, where anaplasmosis was last diagnosed 18 years ago and where its effects are far more severe, Braun explained.

"We think that most Swiss cows have no immunity to the disease," he said.

France is the only other European nation affected by anaplasmosis, with outbreaks occurring in its tropical outpost, Reunion.

Meanwhile, it's still not known how the Swiss herd became contaminated. "We assume that the disease came from abroad, but we are still not sure," says Braun.

Financial loss

The owner of the herd, Markus Mehli, is reportedly in talks with authorities in canton Graubünden in a bid to save around one third of his herd, which he says show no signs of the disease.

The culling of his cows could cost up to SFr1 million, says Mehli, without calculating loss of revenue from milk sales.

Mehli also lost his entire herd three years ago to BSE or mad cow disease.

By Vanessa Mock

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