Deadly bacteria that confounds scientists

The town of Wishaw, near Motherwell, is now the seat of what is believed to be Britain's worst Escherichia-coli 0157 outbreak.

There were calls for government action. The Scottish Labour health spokesman Malcolm Chisholm called for "a clear statement from the Government about what steps have been taken to investigate, monitor and contain this dreadful outbreak".

The bacterium responsible for the outbreak first emerged in Britain in the 1980s. A handful of cases was reported then but the number has been rising ever since.

It takes fewer than 100E-coli organisms to cause an infection. Symptoms include diarrhoea, severe abdominal cramps and vomiting. A proportion of those with the infection, especially children under five and to a lesser extent the elderly, may suffer kidney failure, which can be fatal.

Person-to-person spread can occur and there is no specific treatment for the infection, which can take several days to materialise.

The latest figures from the Public Health Laboratory Service show that in England, Wales and Scotland last year there were 1,039 cases - the sharp rise being partly down to increased testing.

The technical term for the bacterium is Verocytotoxin- producing E-coli, or VTEC. Of the different types, 0157:57 - the one behind the Scottish outbreak - is the predominant cause of human infection.

Children under four have the highest rates of infection, and then the 5-to-14 and over 65 age groups. 0157 VTEC infections usually peak in the summer months.

Scotland has much higher reported rates of infection than the rest of the UK - and no one knows why. An outbreak of 0157 VTEC involving more than 100 people occurred in Scotland in 1994.

Food is the main vehicle of E-coli infection. Undercooked minced beef products, especially beefburgers, raw cow's milk, cheese, contaminated pasteurised milk, and untreated water have all carried the bacteria.

Its ability to transfer from person to person can lead to outbreaks in hospitals, child care centres and nursing homes.

Farm animals, especially cattle, are thought to harbour the bacteria, but the prevalence of 0157 VTEC in British cattle is not known.

A national panic was generated last summer in Japan when an outbreak of the bacterium reached epidemic proportions. It claimed at least ten lives and another 10,000 were taken ill. Most of those affected were schoolchildren and the elderly.

Fear spread throughout the country by the seemingly relentless nature of the outbreaks, and a perplexed nation watched nightly television pictures of scientists testing all sorts of flora and fauna in a desperate attempt to pinpoint the source of the infection.