POPULATION studies of the frequency of multiple sclerosis (MS) carried out in countries at different latitudes1-13 have established that MS is common in temperate climates and rare in regions near the equator. This peculiar geographic distribution of MS may constitute a key to the cause of the illness if its meaning can be properly understood. However, before etiologic hypotheses based on the distribution of MS are elaborated, it is well to realize that there are still many areas of the world in which the frequency of MS has not yet been adequately determined. Latin America constitutes one such area. Existing information is in the form of clinical impressions14 or reports from special clinics15 which are hardly representative of populations as a whole.
The present report provides the first data on MS frequency in Latin America obtained by an epidemiologic analysis of a well-defined population. It
Alter M, Olivares L. Multiple Sclerosis in Mexico: An Epidemiologic Study. Arch Neurol. 1970;23(5):451–459. doi:10.1001/archneur.1970.00480290071008
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