Geographic similarities between varicella and multiple sclerosis: an hypothesis on the environmental factor of multiple sclerosis.
The environmental factor causing multiple sclerosis (MS) is unknown. Kurtzke et al. (Neurology 1979; 29: 1228-1235) depicted a north to south diminishing gradient in the case/control ratios for MS among American veterans in the United States. A similar, but less precise, gradient emerged when the incidence rates of varicella from 37 states during 1978-91 were compared. A loose correlation appears to exist between the mean incidence of varicella and the MS risk ratio (n = 0.344 Spearman rank correlation coefficient, p = 0.037). Further, the data on the fat of migrants moving from a high risk MS country to a low risk country and the reverse, plus the great importance of the age at migration, raise the question of a possible connection between the two diseases. Because of these epidemiological and other similarities between the two diseases a further comparative study was suggested.
Ross
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RT
Section of Neurology, Faculty of Medicine, University of Manitoba, Winnipeg, Canada.
Cheang
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M
D000293:Adolescent; D000328:Adult; D000367:Age Factors; D002644:Chickenpox / Q000453:epidemiology* / Q000209:etiology; D002648:Child; D002675:Child, Preschool; D002980:Climate; D004641:Emigration and Immigration; D004777:Environment; D006801:Humans; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D009103:Multiple Sclerosis / Q000453:epidemiology* / Q000209:etiology; D015995:Prevalence; D012307:Risk Factors; D014481:United States / Q000453:epidemiology; D044465:White People