Persistent infection and vascular disease: a systematic review.

More than 150 epidemiological or clinical studies have reported on associations between vascular disease and the presence of certain persistent bacterial and viral agents, or of clinical conditions (e.g., periodontal disease) that are associated with persistent infection. This article provides a review of such studies, particularly in relation to Helicobacter pylori, Chlamydia pneumoniae, dental disease and cytomegalovirus (CMV), as well as references to possible mechanisms. The association between coronary heart disease and H. pylori or between heart disease and dental disease may be accounted for by residual confounding. Although markers of C. pneumoniae infection are around twenty times more common in atherosclerotic plaques than in disease-free blood vessels, the sequence of infection and disease is uncertain. For CMV, a limited number of patients with classic atherosclerotic coronary heart disease have been investigated in seroepidemiological studies. For all such agents, better and larger seroepidemiological and pathology-based studies are needed to resolve these uncertainties, as well as - at some stage - large-scale, randomised intervention studies.