Fatal sheep virus heads for UK

One of the most feared animal diseases in the world - second only to foot-and-mouth in terms of seriousness - is heading towards Britain because of global warming, a scientist warned yesterday.

When bluetongue virus infects a flock of sheep, it kills or seriously harms up to 70 per cent of the animals. It was posing a real risk to Britain's flock of 40 million animals, said Philip Mellor, a virologist at the Government's Pirbright Laboratory in Guildford, Surrey.

Biting midges spread the virus from one sheep to another, causing blindness, bleeding in the mouth and lameness.

Bluetongue normally extends no further than northern Africa, but over the past decade it had spread into most areas of southern and central Europe, where it was poised to enter Britain, Dr Mellor said.

"It's now been present in Europe for five years, which is longer than it has ever been present in Europe before," Dr Mellor told the British Association for the Advancement of Science at Salford University. He said that it has "expanded more than 800km [500 miles] further north than it has ever been in Europe" and that the spread may "reflect a gradual expansion of this risk area, caused by climate change.

"Every previous outbreak in Europe before has been traced to one [type] of bluetongue virus and now there are five [types] involved," he said.

In southern and central Europethe virus has killed about 500,000 sheep. It is spreading into species of midge that normally live in Britain.

Fewer births lead to breast cancer

Women in rich countries were producing far greater amounts of the sex hormone oestrogen than those in the developing world, which could explain the higher rates of breast cancer in the Western world, a scientist told the conference.

The falling birth rate in the West had led to women having on average 400 menstrual cycles compared with about 100 in Third World countries where the birth rate was higher, Tessa Pollard, a biological anthropologist from Durham University, said. "In this context, we can understand our high levels of breast cancer more easily."

Learning problems are genetic

Children who are poor at reading are not disabled but responding to genetic influences, a psychologist told the conference.

Professor Robert Plomin of King's College London studied 7,500 sets of identical and non-identical twins since 1998 and concluded that if one identical twin suffered a learning disability, there was a 72 per cent chance of the other twin -- who shares the same genes -- suffering the same disability, compared with a 45 per cent chance in non-identical twins. He said: "These findings suggest that there are no disabilities, just extreme variations of ability within a normal distribution."