Analytical epidemiological study of multiple sclerosis in Alcoi

INTRODUCTION: Multiple sclerosis (MS) is a disease of controversial epidemiology, which has frequently been studied. The results of an epidemiological descriptive study in the Alcoi area led to a first case-control study to give information about the factors associated with the illness in this area. It was seen from this that migration, contact with dogs and with cloth might be related to it. OBJECTIVE: To carry out a second analytical study, maintaining the migration factor stable to avoid the possible confounding effect with other associated factors. MATERIAL AND METHODS: For this case-control study we grouped one case with four controls from the population according to age, sex and place of birth. All cases fulfilled criteria defined for MS and the controls were randomly selected from the census. We also classified the cases and controls into three groups, according to whether or not migration was involved (group A: Autochthonous; group B: Immigrants who arrived before the age of 13, and group C: Immigrants who arrived after the age of 13). RESULTS: We analyzed 40 patients and 160 controls. We obtained significant values for 'social group'. The cases belonged to the less favored social group both on overall analysis and in the autochthonous group. Pneumonia was the only infection with significant figures in patients over 15. Contact with dogs gave new statistically significant figures, together with cloth and cloth products. CONCLUSIONS: Persistence of positive correlation of MS with contact with dogs and cloth suggest the possible influence of these two factors in the increase in incidence of MS in this area.