Background and purpose: Recent studies suggest an association of coronary heart disease and carotid atherosclerosis with Chlamydia pneumoniae infection. We investigated the frequency of chlamydial seropositivity and specific circulating immune complexes in patients with recent cerebrovascular disease.
Methods: Specific antibodies to C pneumoniae in serum were measured by the microimmunofluorescence test in 58 consecutive patients (aged 18 to 50 years) with ischemic infarction (n = 39) or transient ischemic attacks (n = 19) and in 52 hospital control subjects without vascular disease, matched for sex, age, time, and locality.
Results: Twenty-seven patients (46.6%) and 12 control subjects (23.1%) had raised IgA titers > or = 1:16 (P = .018). IgG titers > or = 1:32 were measured in 74.1% of the patients and 77% of control subjects (P = .623). Specific IgG antibodies in circulating immune complexes, which were isolated by polyethylene glycol precipitation, were elevated > or = 1:8 in 24.1% of the patients and 7.7% of control subjects (P = .047). With the use of a conditional logistic regression model, the odds ratios were 1.70 (95% confidence interval [CI], 1.13 to 2.58) for elevated IgA titers, 1.91 (95% CI, 1.06 to 3.47) for the presence of immune complexes, and 1.96 (95% CI, 1.00 to 3.82) for the presence of both factors. After adjustment for the vascular risk factors hypertension, age, sex, and migraine, the odds ratios were 1.71 (95% CI, 1.08 to 2.70), 2.00 (95% CI, 1.07 to 3.76), and 2.20 (95% CI, 1.09 to 4.41), respectively.
Conclusions: We conclude that chronic infection with C pneumoniae is associated with an increased risk of stroke and transient ischemic events.