More than a hundred people are now suffering severe stomach sickness and diarrhoea, in one of the worst outbreaks of water-borne infection to hit the South-east in the past five years. But sources investigating the crisis say they are now hoping a "plateau affect" will kick in and reduce the number of cases, presently rising daily.
French-owned Three Valleys Water issued a "boil water" warning to homes in west Hertfordshire, north-west London and Bedfordshire, after a number of people contracted cryptosporidiosis. The infection, which causes severe diarrhoea lasting up to three weeks, is potentially fatal for children and people with deficient immune systems, such as the elderly.
A spokesman for Bedfordshire Health Authority said: "We decided to hospitalise four elderly people because we are aware that the illness can cause severe distress and possible death, in the weak and frail.
"However, I am pleased to say that the four are currently in a stable condition and responding well to treatment."
Cryptosporidium, which has between a seven and 10-day incubation period, causes 4,000 cases in Britain each year. Belonging to a group of protozoa, it occurs naturally in the dung of farm animals, which can be washed from agricultural land into nearby rivers.
It is normally spread through contaminated water or contact with an infected person, but unpasteurised milk and offal also carry risks.
Frank Fitzpatrick, communication manager for Three Valleys, said: "We are leaving no stone unturned in order to find the origin of this problem, if indeed it is related to the water supply."
The company - which is currently spending pounds 40,000 a day on increased sampling - is supplying local schools and hospitals with bottled water.
Independent inspectors from the Government Drinking Water are carrying a detailed investigation into the outbreak.
If they decide the company has been negligent in its treatment of the water supply then Three Valleys may face prosecution and the prospect of paying thousands of pounds in compensation.Reuse content