London (CNSNews.com) - Vaccines are once again implicated as a potential cause of ill health in veterans of the Gulf War, with a new study saying servicemen who received multiple inoculations during deployment were five times more likely to suffer.
Results of the study are published in the British Medical Journal Friday.
But it appears that differences over the "Gulf War Syndrome" phenomenon, including the question of whether indeed it exists, will not be put to rest, since experts are questioning the new conclusions.
Since the 1991 Gulf War, when a U.S.-led military alliance reversed the Iraqi invasion of Kuwait, some veterans have complained about chronic fatigue, infertility and mental illness.
British troops serving in the Gulf were vaccinated in the months leading up to and during deployment, to protect them against the risks of biological warfare and infectious diseases - anthrax, whooping cough, plague, tetanus, cholera, hepatitis, polio, yellow fever and typhoid.
Researchers at the Gulf War Research Unit at the Guy's, King's and St Thomas' School of Medicine in London have now investigated claims that the vaccination program may be responsible for the symptoms.
They found that servicemen who received multiple vaccinations during deployment were five times more likely to suffer from a range of health problems.
Curiously, those vaccinated before deployment did not appear to have been affected. One possibility is that troops' stress in the combat zone may have had some kind of interaction with the vaccines, although the researchers found no evidence of this.
Neither was any interaction between vaccines and the use of pesticides discovered.
"Multiple vaccinations in themselves do not seem to be harmful but combined with the stress of deployment they may be associated with adverse health outcomes," Matthew Hotopf and his colleagues write in the BMJ.
The study was limited to veterans who had kept their vaccine records.
Writing in the same edition of the BMJ, Guy's, King's and St Thomas' School of Medicine public health specialist, Dr. Seif Shaheen, warned that the research was inconclusive and said the results "demand cautious interpretation."
Potential exposure to other agents was not taken into account, he noted.
Shaheen said it was possible that unaffected veterans may have given exaggerated information about vaccinations after learning from media reports that they may be eligible for financial compensation if the hypothesis was confirmed.
Whatever the case, he said, it would be wise to keep routine vaccination of armed forces personnel up to date during peacetime - before they were sent to warzones.
Campaigners claim the "syndrome" affects some 100,000 veterans, about 2,700 of them in Britain. Some believe uranium used in weapons may be the cause.
"We are pleased that this research has found a link between multiple vaccinations and the syndrome," Shaun Rusing, chairman of the National Gulf Veterans and Families Association, said in a statement.
"We were used as guinea pigs during the war. Our bodies were abused and we were let down by the Ministry of Defense," added Rusin, himself a sufferer.
The British Royal Legion, the UK's association for war veterans, says it will "continue to press for an independent public inquiry to identify the shortcomings in investigating health problems experienced by Gulf War veterans and recommend improvements in procedures for dealing with similar post-conflict situations."
Blood tests on ill American Gulf War veterans last year showed that many produced high levels of antibodies against a substance used in vaccines, called squalene.
Other veterans of the war, who showed no symptoms associated with the "syndrome," did not produce antibodies - which is considered a normal reaction.
Researchers suggested that the symptoms suffered by veterans could be the result of the body turning its immune system against its own natural supply of squalene.
But at the time these findings were published, the U.S. Defense Department denied that squalene was used in its vaccines.
The study was conducted by virologists at Tulane University in New Orleans.