91av

CAN you catch a stroke? Sometimes, is the answer according to the largest study to date.

Infection with bacteria such as Chlamydia pneumoniae has already been linked with heart disease (91av, 31 March 2001, p 18). Such infections may trigger inflammation that leads to plaque formation in the arteries, or atherosclerosis.

There is no conclusive evidence of a link between C. pneumoniae and strokes. But most previous studies relied on finding antibodies of a type known as IgG, which are not good markers for active infection as they persist for decades.

Mitchell Elkind’s team at Columbia University in New York looked instead for IgA antibodies to C. pneumoniae, which last only a week or so after an infection. After adjusting for other risk factors, the team found that people with raised levels of IgA antibodies against Chlamydia were 50 per cent more likely to suffer a stroke than those with normal levels, he told a meeting of the American Academy of Neurology in Honolulu earlier this month. The investigation involved 250 stroke patients and 337 controls.

“This is not going to be the smoking gun that’s going to answer what causes stroke,” says Elkind. “Think of it as another risk factor like hypertension, cholesterol, smoking and diabetes, in that it’s contributing to the development of atherosclerosis.”