A common cold bug could cause heart attacks in younger men, US researchers reported on Tuesday.
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.