A nationwide alert has been issued after a new batch of contaminated heroin, which previously killed more than 40 people mostly in Scotland, was discovered.

A nationwide alert has been issued after a new batch of contaminated heroin, which previously killed more than 40 people mostly in Scotland, was discovered.

Heroin batches contaminated with the Clostridium bacterium is at the centre of the new scare which has already claimed one life.

A batch of heroin contaminated with the bacterial spores is thought to be at the centre of infection cases in Essex and Kent.

The Health Protection Agency has sent a circular to health service organisations and partners, including needle exchanges, to warn of the new contamination.

Inquiries are understood to be under way about whether the new outbreak is linked to a potentially fatal batch of contaminated heroin, known as "red heroin", being sold in Scotland. Last week Strathclyde and Dumfries and Galloway police forces issued warnings to addicts not to use the "red" substance.

The Scottish Crime and Drug Enforcement Agency is also ensuring the message about the heroin contaminated with Clostridium goes out in Scotland, which was hardest hit by the previous outbreak seven years ago.

Then, there were a total of 108 cases - 60 in Scotland, including 50 in Glasgow, 26 in England and 22 in Dublin. There were 43 deaths with more than 20 in Glasgow.

Epidemiological analysis combined with police investigations in Glasgow and Dublin showed the distribution of cases coincided with specific networks of drug supply. Analysis of the contaminated heroin found it was derived from opium produced in Afghanistan.

Extensive microbiological investigations led to the identification of Clostridium novyi Type A from 13 cases in Scotland, two in Dublin and two in England.

C novyi is most commonly associated with infection in farm animals and human battlefield victims.

Experts say illness typically developed in long- standing drug injectors who had injected into muscle. Citric acid often added to the drug before injecting may help "activate" the spores.

After several days of infection there was moderate to severe inflammation at the point of the injection, followed in many cases by "multi- system failure" and death despite intensive treatment.

Experts from the Health Protection Agency say that there was further concern in 2001 that part of the batch of heroin that may have been the source of the original outbreak was again in circulation, and in December 2003 to March 2004 a similar outbreak occurred due to Clostridium histolyticum.

The agency said that continued vigilance is now required to detect, promptly treat, and report any further cases.

It has also warned medical staff in hospitals to watch out for the symptoms so that cases are reported to consultants in communicable disease control sections of health protection units and properly recorded.

The Health Protection Agency said: "Between April 1 and August 1, 2000, over 30 heroin injectors died from a serious rare infection. Since June 2008, new cases have been identified and a further death.

"Doctors think that an infection in the muscle tissue of these drug users - caused by a bug called Clostridium - gets steadily worse over a few days. Eventually, the bacteria in the muscle release enough toxin into the bloodstream to cause a very severe illness which often leads to rapid death."

They say the drug users affected have usually injected heroin into a muscle or under the skin, known as skin- popping, and have had swelling, redness and pain where they have injected themselves.

"It is not certain whether only one batch of heroin is responsible for the recent cases, or if many supplies of heroin might have been affected," the agency said. "This infection can only be caught by injecting. It can't be caught by having sex or living with a drug user who has the infection."

Medical experts urge anyone with symptoms to get to hospital quickly - but warn that the infection is hard to treat, even with modern antibiotics. Surgeons can cut away the dead tissue containing the bacteria.