AN outbreak of tetanus among drug addicts has now claimed 10 lives, with the discovery of another case yesterday bringing the total number of victims to 26. The infections have prompted the Health Department to take the unprecedented step of introducing free tetanus shots at all of its 23 methadone clinics from tomorrow in a bid to stop the spread of the disease. The latest death occurred on Tuesday, with 15 patients still in hospitals throughout the territory. All 26 cases were discovered in the past two months. The Assistant Director of Health for Special Health Services, Dr Lam Ping-yan, said: ''We have extended the immunisation programme to all clinics to try to protect all drug users who are most vulnerable to the disease.'' Although testing of heroin samples have not shown them to contain the bacteria which causes tetanus, the Health Department believe contaminated heroin is still at the root of the outbreak. All 26 victims had a history of injecting drugs and the department has said there is no cause for alarm among the public, although immunisation was advisable. Symptoms include stiff muscles and muscular spasms throughout the body which often lead to a heart attack and death. Two weeks ago the Health Department introduced tetanus shots at three methadone clinics and 660 drug users have already been immunised. But Dr Lam urged other addicts in Hong Kong, thought to number more than 20,000, to come forward for the vaccine. Dr Lam said: ''It is still difficult to say whether the number of infections has peaked or not because there could still be more contaminated heroin out there. ''The disease can also have an incubation period of up to several months so we could still have more cases to come.'' Five cases have come from Shamshuipo, four from Kwun Tong, three from Kowloon City, one from Mongkok, one from Wong Tai Sin, while the latest case is unknown. Dr Lam added: ''We will be stepping up our publicity campaign to highlight the risk of tetanus to drug users in the hope that more people will get themselves immunised.'' The Health Department has enlisted the help of Correctional Services, narcotics police and the Society for the Aid and Rehabilitation of Drug Abusers to disseminate the information to all drug addicts. Tetanus is due to become a notifiable disease under an amendment of the Quarantine and Prevention of Disease Ordinance which will strengthen the existing reporting system and enable quicker implementation of disease control measures. A tetanus immunisation hotline service will come into operation during office hours on Monday on 835 1831 and 835 1834.