WESTPORT, CT (Reuters Health) May 08 - Late infection with common viruses is associated with an increased risk of multiple sclerosis, according to findings from a case-control study nested within the Nurses' Health Study II.
Dr. Miguel A. Hernan, of the Harvard School of Public Health in Boston, and associates identified 301 women with MS and matched them with 1416 healthy controls. The subjects completed questionnaires regarding such issues as lifetime history of various viral diseases and exposure to pets.
The odds ratio of a subject with a history of infectious mononucleosis developing MS was 2.1, the researchers report in the May issue of Epidemiology. For mumps or measles after age 15, the odds ratios were 2.3 and 2.8, respectively.
"Whether these viruses cause the elevated risk or are only surrogates for the actual etiologic exposure cannot be determined from our findings," Dr. Hernan's group cautions.
The investigators observed no association of MS with other common viral diseases, exposure to canine distemper virus, cat ownership, birth order or number of siblings. The risk of MS was moderately increased among dog owners, "but the 95% confidence interval was wide."
2001 Reuters Ltd.