They have linked the outbreak - which started on 20 February - to a massive plume of sand that swirled out of northern Africa several days earlier.
'Satellite images show a dust cloud moving over the Atlantic and reaching Britain on 13 February,' said Dr Dale Griffin, of the US Geological Survey. 'One week later, foot and mouth broke out in the UK. Given that the disease's incubation period is seven days, that is one heck of a coincidence.'
Britain's foot and mouth epidemic has cost billions of pounds, affected 2,000 farms and led to the slaughter of four million animals.
The idea that it could have been triggered by an atmospheric dust cloud from Africa is startling. Nev ertheless, scientists are becoming increasingly worried that similar events are common and are responsible for countless other epidemics. These include an illness now destroying Caribbean coral reefs and asthma outbreaks in Barbados and Puerto Rico.
The problem is being taken so seriously that scientists meeting in Florida last month urged that a major research programme on dust epidemics be established. They have earmarked several desert danger zones, of which the Sahara is considered most serious.
'There is no sewage treatment or proper garbage disposal there - so the soil is heavily infected with microbes and faeces,' said Dr Eugene Shinn, another US geological survey scientist. 'Cattle there are also infected with the same viral strain, type O, that is causing foot and mouth in Britain.'
Storms frequently carry dust from the Sahara to Britain and their incidence is increasing, thanks to climate changes. Rainfall there is declining and deserts are spreading - creating more and more dust clouds that are funnelled westward to the Caribbean by summer trade winds and northward into Europe during winter.
For years, researchers assumed bacteria, viruses and fungi caught up in such clouds would be sterilised by the sun's ultraviolet rays. But now scientists have discovered they may be finding protection against radiation by clinging to dust and sand particles.
Griffin and his team analysed several dust clouds, and found a wide range of plant and human pathogens. Crucially, these samples were obtained by making cultures. 'Only live organisms can generate cultures, which shows we are dealing with microbes that are still infectious after their Atlantic crossing,' he said.
This point was backed by Ginger Garrison, a marine ecologist in Florida, following her analyses of samples taken during dust storms. 'We found a load of micro-organisms hitchhiking on dust particles across the Atlantic,' she states in the journal Nature.
One micro-organism was the fungus Aspergillus sydowii, blamed for the current destruction of Caribbean coral reefs. 'The fungus is a (common soil) organism that produces airborne spores and does not reproduce in sea water, yet it is affecting coral reefs,' said Shinn. 'Our research suggests an explanation. It is falling from the sky.'
Similarly, scientists suspect asthma outbreaks in the Caribbean and US may also be linked to dust storms.And it is just this mechanism that may have triggered Britain's foot and mouth epidemic, adds the US group. The virus can survive for long periods outside a host animal - 'just the attribute to linger in dust, and still be infectious when it reaches a new country,' said Shinn.