Blood tests have revealed that some of the cattle are antibody positive for bovine immunodeficiency virus (BIV), a relative of the human Aids virus, HIV. Government officials have taken away further samples for testing and are expected to report the findings this week. It would be the first time the virus has appeared in Britain.
Every animal in the herd is sick and many of the symptoms - muscle-wasting, ulcers, skin problems and respiratory difficulites - are uncannily similar to human Aids. The Independent on Sunday understands that at least two other farms in England are suffering from similar problems.
The Milk Marketing Board confirmed that it decided last week not to take any more milk from the farmer because the dairy firm that has bought his produce for the past 10 months no longer wanted it, citing the health of the herd as the reason.
The Ministry of Agriculture Fisheries and Food was anxious to play down the risks to human health. A spokesman said that the animals could be used for human consumption and no quarantine restrictions had been imposed.
The Cheshire farmer, who faces finanical ruin, has asked to remain anonymous. He said he first noticed unusual symptoms in his herd after the arrival last year of new stock from Holland and Germany. The illness appears to pass 'vertically' from cow to calf and 'horizontally' among cows.
Ministry vets have been visiting the farm for several months and have tested 'for everything', said the farmer's wife, but they can find no single cause for the illnesses. 'They've so far tested eight animals for BIV and we've had two positive for antibodies. It's affected everything. Everything is poorly, absolutely everything,' she said.
A ministry spokesman said that positive antibody tests for BIV were not new in this country: a random survey of about 200 cattle a year ago revealed that some were BIV-positive. The survey had not been published because 'there was no reason to do so'.
Joe Brownlie, a virologist at the Institute for Animal Health in Berkshire, said there was a close relationship between BIV and its human counterpart, HIV, but he was in 'no doubt that it is not a risk to human health'. It had not been possible, for instance, to infect human cells in the test tube with the bovine virus, he said.
American scientists first found BIV in 1972 but thought it was a different type of virus until they re-analysed frozen samples 15 years later and noticed the close similarity to HIV.
Antibody tests suggest the bovine virus is present in about 8 per cent of American cattle. How and when the virus causes disease is not fully understood, although it has been linked with swelling of the lymph glands, progressive weakness and neurological disorders.
In addition to humans, cats and monkeys are infected with immuno-deficiency viruses which can cause illnesses that are similar to Aids.
Cows with Aids, page 2