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No Causal Role Found for Chlamydia Pneumoniae in Multiple Sclerosis: Presented at AAN
By Jill Stein
HONOLULU, HI -- April 2, 2003 -- Individuals who are infected with Chlamydia pneumoniae do not appear to be at increased risk of multiple sclerosis (MS), investigators reported here April 1st at the 55th Annual Meeting of the American Academy of Neurology.
While earlier studies examined a possible causal association between MS and C. pneumoniae, their cross-sectional design did not allow researchers to determine whether infection preceded the onset of MS.
Dr. Kassandra L. Munger, with Harvard School of Public Health, Boston, Massachusetts, and colleagues elsewhere, conducted a case-control study that included 3 million U.S. military personnel and over 121,466 subscribers to the Kaiser Permanente Medical Care Program.
At least one serum sample collected before the onset of MS was available among 83 Army personnel with MS and 46 cases among Kaiser-Permanente members, and all were included in this study. Two controls were matched to each case for age and sex, and army controls were additionally matched to cases by race and date of blood collection.
The MS diagnosis was determined by medical record review. The date of MS onset was the earliest date of neurologic symptoms attributed to MS as stated in the medical records.
Serum C. pneumoniae specific immunoglobulin G (IgG) antibody titer levels were measured using microimmunofluorescence.
Results showed no association between seropositivity for C. pneumoniae and an increased risk of MS. Overall, 69% of military personnel and 63% of Kaiser-Permanente subscribers were IgG seropositive compared with 66% and 53% of controls, respectively.
Geometric mean C. pneumoniae IgG titer levels among seropositive military personnel did not differ significantly between cases and controls, relapsing-remitting cases and controls, or primary progressive cases and controls. On the other hand, in the Kaiser Permanente group, geometric mean C. pneumoniae IgG titer levels were significantly higher in the seropositive cases than in controls (146 versus 64, P=0.009).
This difference was more dramatic for both primary and secondary progressive cases than for relapsing-remitting cases.
While their data did not identify a role for C. pneumonia infection in the etiology of MS, the possibility that infection with C. pneumonia before the onset of MS might trigger progressive disease cannot be eliminated, the investigators emphasized.
The study was supported by National Institutes of Health and the National Multiple Sclerosis Study.
[Study title: A Prospective Study of Infection with Chlamydia pneumoniae and Risk of Multiple Sclerosis in Two Large US Cohorts. Abstract: P01.104]
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