Multiple sclerosis is prevalent in the Zoroastrians (Parsis) of India

Using Schumacher's classification, we determined the prevalence rate of clinically definite multiple sclerosis (MS) in the distinct but tiny Zoroastrian (largely Parsi) community in the adjacent cities of Bombay (latitude, 18.55 degrees) and Poona (Pune). On prevalence day, 16 clinically definite cases of MS were counted, 14 in Bombay and 2 in Poona, from a total Zoroastrian population of 50,053 and 3,399, respectively. The crude prevalence ratio was 26 per 100,000 for Bombay and 58 per 100,000 for Poona. The age-adjusted prevalence ratio for Bombay was 24 per 100,000, with 95% confidence limits of 13.1 to 40.3. These are much higher than the low rates believed to be prevalent in India, and are comparable with those found in parts of Europe and the United States.