By Maggie Fox, Health and Science Correspondent
WASHINGTON (Reuters)

People who get infections over and over again, such as sinus infections or bronchitis, may also be more prone to clogged arteries, doctors said on Monday.

A study of more than 800 men and women in Europe showed that those who had recurrent infections were also much more likely to develop artery-clogging plaques.

The culprit may be the body's inflammation response, the researchers in Austria and Italy said.

'Ours is the first study to assess a strong relationship between various types of common chronic infections and atherosclerosis,' Dr. Stefan Kiechl, professor of neurology at Innsbruck University Clinic in Austria, said in a statement.

'Our study provides further strong evidence that chronic infection increases the overall risk of blood vessel disease.'

Researchers believe that inflammation may be strongly linked with clogged arteries. The plaques that form these clogs are created when immune system cells latch onto fat cells in the blood and try to pull them out through the cell wall.

The fat cell is often too big and it gets caught. Over time, the trapped immune and fat cells build up in the artery wall, become calcified and can block blood flow or even break off into dangerous clots.

Inflammatory responses to infection can send more of these immune cells circulating, looking for something to do.

Writing in the journal Circulation, issued by the American Heart Association, Kiechl and Italian colleagues said they looked at 826 men and women, aged 40 to 79, over five years.

They examined their carotid arteries, which provide the main blood supply to the brain, and asked the patients about how much they smoked, drank, and whether they had high blood pressure or diabetes. They asked about infections such as sinusitis, bronchitis and urinary tract infections.

They also looked for markers or indicators of inflammation such as C-reactive protein (CRP).

Heart Disease Higher In Infected Patients

'Among subjects with chronic infections, the risk seemed to be higher in those with a prominent inflammatory response,' Kiechl said. 'This may indicate that the risk is associated with the toxic effect of the inflammation itself or the body's immune reaction to it.'

Of the 826 volunteers, 268 had chronic infections. The older the people were, the more likely they were to have chronic infections. People of low socioeconomic status, those who smoked and those who drank heavily were also more prone to the chronic infections.

By the end of the five years, 332 or 41 percent of the men and women had new plaques in their carotid arteries. Those with any chronic infection were nearly three times more likely to have grown the new blockages.

Bacterial infections such as bronchitis and sinusitis seemed to be the biggest causes, Kiechl said. One bacterial infection did not seem to be any more linked to the plaques than any other.

People who had herpes zoster virus, which causes chickenpox and shingles, or hepatitis infections, did not seem to have a higher rate of plaque development.

'We believe the principles and main risk factors for atherosclerosis are the same for carotid, coronary and femoral (leg) arteries,' Kiechl said.

The researchers said it was far too early to recommend that people take antibiotics long term to suppress inflammation. Although several studies have linked infection with heart disease, none has shown that people who took antibiotics had a lower risk of heart disease.

Several studies have now shown the link with infection, however. Researchers have found that people infected with herpes simplex, the virus that causes cold sores, are twice as likely to have a heart attack or die from heart disease as uninfected people.
Another team found that 85 percent of heart attack patients also had periodontal disease.