The geographical distribution of multiple sclerosis, rheumatoid arthritis, rheumatic heart disease and poststreptococcal nephritis in Sardinia: climatic and socioeconomic factors.

The comparative geography of multiple sclerosis (MS) and nonneurological diseases considered to be autoimmune is of great interest. But there are few appropriate investigations. Some have found an increase in the frequency of MS, rheumatoid arthritis and rheumatic heart disease depending on the geographic latitude. Nevertheless, the significance of the latitude effect as an indicator of a possible etiological relationship between MS and these conditions has been questioned. In this paper, the frequency of MS, rheumatoid arthritis, rheumatic heart disease and poststreptococcal nephritis is reported from Sardinia where appreciable differences in climatic and socioeconomic conditions exist. There was a positive correlation of the distribution of MS with the distribution of rheumatic heart disease and poststreptococcal nephritis. On the other hand, no correlation was found with the distribution of rheumatoid arthritis.