by Natalie Salat

Following a recent Health Canada review, several thousand Canadian Forces members who were vaccinated against encephalitis carried by ticks in Eastern Europe are being informed of a possible health risk associated with the vaccine.

The risk stems from the use of FSME Immun, an Austrian vaccine used by the Forces, which contains proteins from the blood of German and Austrian donors. In 1999, Health Canada banned the use of blood products from European donors in order to reduce the potential for transmission of variant Creutzfeldt-Jakob disease–vCJD–better known as the human form of mad cow disease.

The rare but fatal brain disease is linked to the consumption of contaminated beef products from animals infected with bovine spongiform encephalopathy. Of the 134 cases of the disease reported worldwide as of July 2002, most have come from European countries.

In July, Health Canada announced that anyone who received or receives the vaccine must be informed of the risk. Although the vaccine is not licensed in Canada, it can be obtained through the department’s special access program.

Commander David Carpenter, head of the Canadian Forces’ communicable disease control program in Ottawa, says the Forces are in the process of identifying current or former members, along with any dependants, who would have been vaccinated. He says approximately 4,500 Canadian military staff received the vaccine during Canada’s early peacekeeping operations in the former Yugoslavia, between 1991 and 1994. Several hundred more have been vaccinated for duties throughout Europe, including military attachés at embassies.

Carpenter emphasizes that the risk of contracting the disease through blood products is only theoretical. “There has never been a case of somebody getting variant CJD from any blood product,” he says. “Health Canada has estimated that if there were a risk, it would be one in 100 million people.”

He adds that the risk of military staff contracting tick-borne encephalitis when stationed in Europe was–and remains– real, requiring vaccination. This infectious disease of the brain occurs in many areas of Europe, with hundreds of cases reported each year. No specific treatment exists, and the disease proves fatal in one to five per cent of cases, according to Health Canada.

“If you get bitten by a tick that is carrying the disease, you have a very high risk of getting TBE,” says Carpenter. By comparison, the risk of contracting vCJD from the vaccine is minute, he adds.

Major Rick Jones, a public affairs officer for the Forces medical group in Ottawa, says electronic and paper-based searches are taking place to identify those affected. He says the most difficult task is to locate former members of the Forces for whom the electronic or paper trail suddenly ended.

In addition to notifying those already vaccinated, the Forces are sending information packages to medical units at all levels and to individuals for whom the TBE vaccine is recommended or required. FSME Immun continues to be used in the Forces, as well as by Health Canada and travel medicine clinics.

Carpenter says that people who have received the vaccine have no real cause for worry. Putting the risk in perspective, he says, “If we gave everyone in Canada the vaccine, only one third of a Canadian would have the possibility of contracting CJD.”