On 13 May 2000, Vidyya first brought you the stories of several mysterious drug deaths among heroin users in Scotland. Since then there have been similar deaths in Ireland and England. Experts now believe the deaths may have been caused by the anaerobic bacteria, Clostridia.

Researchers are working to find the cause of the illness. "We are exploring all potential etiologies," said Dr. Brian Duerden, medical director of the Public Health Laboratory Service in London. "The pattern of illness is one of localized infection at the injection site, followed by a systemic infection similar to a toxic shock reaction. It is highly suggestive of a Clostridia infection."

To date, 14 have died and 15 others have taken ill in Glasgow, Scotland. In Dublin, Ireland 8 have died and 15 taken ill under similar circumstances. All are heroin users that have injected the drug into their muscles or just below the skin, rather than into their veins. Officials in London report that seven have died in England and Wales under similar circumstances since April 24th. They are currently reviewing their case files to determine if a link to the Scottish outbreak exists.

The Public Health Laboratory Service, England's version of the US Centers for Disease Control and Prevention (CDC), is working with the Scottish and Irish authorities to provide testing and support. "If in fact it is Clostridia, it is very difficult to detect under normal laboratory conditions," Duerden noted.

To augment their investigation, officials from both countries called upon the CDC in Atlanta. "There has been excellent cooperation amongst the international community. Doctors are talking to doctors and that is what we need," said Maureen Browne, communications director of the Eastern Regional Health Authority in Dublin, Ireland. "The police forces of both countries have their investigations as well, but our concern is assessing and managing the public health risk."

Media reports have attempted to link this outbreak to a series of deaths among heroin users occurring in San Francisco in June of 1999. Those cases were attributed to black tar contamination of the drug. "Clearly, the heroin in Scotland and Ireland is also contaminated with something, but we can't link this to the San Francisco outbreaks," Duerden said.

Officials ruled out anthrax as a potential contaminant early on. They also explored the possibility that citric acid, mixed into the heroin, may be the culprit. "The citric acid may certainly be contributory to the problem," Duerden said. "It causes localized tissue damage and necrosis at the injection site and may be establishing the ideal environment for a superinfection to grow, but the clinical signs clearly point to a bacterial infection."

The patients hospitalized have all had white blood cell counts between 4,000 and 135,000, which would support the bacterial superinfection theory. However, these individuals have not responded to broad-spectrum antibiotics.

"We have established a protocol that laboratory cultures from these individuals will be reviewed for 10 days to insure that all bacterial possibilities are explored," Duerden said.