A common cold bug could cause
heart attacks in younger men, U.S. researchers reported.
The findings add to a growing
body of evidence that Chlamydia pneumoniae and perhaps other
infections can sometimes damage the heart and arteries,
causing heart disease.
Christine Arcari and colleagues
at the University of Wisconsin Medical School and Johns
Hopkins University in Baltimore studied regular blood samples
taken from soldiers aged between 30 and 50, identifying
300 of them who suffered heart attacks.
They compared their blood
records to 300 men who had not suffered heart attacks.
Writing in the journal Clinical
Infectious Diseases, the researchers said they tested each
blood sample for antibodies, which provide indirect evidence
of previous infection.
There is no direct test for
infection with Chlamydia pneumoniae, a bacteria that causes
a flu-like upper respiratory infection that sometimes worsens
to pneumonia.
They looked specifically
for two antibodies -- IgA and IgG -- that recognize and
attack chlamydia bacteria.
"IgG antibodies are like
a long-term memory, while IgA is thought to be a more specific
marker for recent or chronic infections," Arcari said.
Men who had high levels of
IgA antibodies were more likely to have had serious heart
attacks, they found. And the more recent the infection,
the more likely they were to have suffered a heart attack.
"This indicated the possible
importance between the time of infection and the date of
the cardiac event," Arcari said.
Dr. Javier Nieto, chair of
the Department of Population Health Sciences at the University
of Wisconsin, said it may be difficult to say yet how the
findings may be used.
"Since Chlamydia infection
is so common, by the time people reach 65 years of age,
most will have been exposed to it," he said. "By looking
at infection in younger people, we may be able to identify
early stages of atherosclerosis."
Experts believe that infections
may cause inflammation or perhaps an abnormal immune response
in some people that damages the heart and arteries.
