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Tuesday, 8 January, 2002, 00:12 GMT
Infection's role in heart disease
heart massage
Clogged heart arteries cause heart attacks
Evidence suggesting that infections may contribute greatly to heart disease, has been reinforced by researchers.

While lifestyle and genetics are likely to play the greater role in the development of the killer illness, many doctors now accept there are other factors at work.

In particular, it is thought exposure to lingering infections may create the conditions necessary for heart arteries to narrow and harden, a process called atherosclerosis.

A study, published in the journal Circulation on Tuesday, has found a direct association between the number of infections to which a cardiac patient has been exposed, and the likelihood of death in the following three years.

Which came first?

However, it is still impossible to rule out the possibility that sicker cardiac patients fall prey to more infections because of their weakened condition, not the other way around.

It's now reasonable to assume that infections play a part in the development of atherosclerosis

Professor Juan Carlos Caski, St George's Hospital
A group of researchers from Johannes Gutenberg University in Mainz, Germany, looked at 572 heart patients.

They tested for antibodies in the bloodstream which would show that the immune system had at some stage been exposed to a variety of different viruses and bacteria.

These included herpes simplex 1 and 2, which cause cold sores and genital herpes, Epstein-Barr virus, which causes mononucleosis, Chlamydia, flu virus and Helicobacter pylori, which causes stomach ulcers.

Then they looked at the patients again three years later to see how many had survived.

The death rate was 3.1% in patients who tested positive for only a few of the viruses or bacteria, 9.8% for those with four or five, and 15% in those positive for six to eight.

Inflamed tissues

Among those who had the most advanced artery hardening, 20% of those exposed to between six and eight infections had died, compared to 7% of those with three or fewer.

Dr Hans Rupprecht said: "We showed a significant association between the number of infections to which a patient has been exposed and the extent of atherosclerosis in the arteries of the heart, neck and legs."

The reason behind the link is not totally clear, but most likely is the fact that some of the infections can cause inflammation in the body's tissues.

This can last for a long period while the immune system moves to eradicate the infection.

It has been suggested that this inflammation, when present in the lining of the arteries, can contribute to atherosclerosis.

Long-lasting infections

It is possible that aspirin, and cholesterol-lowering drugs, may work partly by reducing this inflammation.

Professor Juan Carlos Caski, from St George's Hospital in London, who specialises in the links between infections and heart disease, told BBC News Online: "It's now reasonable to assume that infections play a part in the development of atherosclerosis.

"This work is quite important because it endorses other results showing that there may be this link, and that it is not just a single infection, but more than one.

"It is likely to be chronic infections - chlamydia, for example, can persist for some time in circulating cells - which could be causing the problem."

See also:

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