title: Monthly variation of multiple sclerosis activity in the southern hemisphere: analysis from 996 relapses in Brazil.
abstract: OBJECTIVE
  Seasonal variations of multiple sclerosis (MS) activity have been reported, however, most data come from studies in the northern hemisphere.
  
  
  METHODS
  We reviewed medical records of MS patients living in Campinas region, Brazil. The first symptoms' date was defined as the relapse month. Climatic information included UV radiation index, median temperature, rainfall, and humidity.
  
  
  RESULTS
  Two hundred and nine patients were included. The incidence of relapses was highest in January (11.2%) and December (10.4%) and lowest in November (5.7%) and October (7.0%) (P < 0.015). The months with highest incidence of relapses (December-January) had higher UV radiation index and humidity rates (P = 0.032 and 0.040, respectively).
  
  
  CONCLUSIONS
  Most exacerbations were in the spring/summer transition, which also showed higher UV radiation index and humidity rate. Along with other environmental factors, seasonal fluctuation contributes to MS activity.
authors.affiliation: Department of Neurology, University of Campinas, Campinas, Brazil. alfredodamasceno@hotmail.com
authors.forename: A
authors.initials: A
authors.lastname: Damasceno
authors.forename: F
authors.initials: F
authors.lastname: Von Glehn
authors.forename: L
authors.initials: L
authors.lastname: de Deus-Silva
authors.forename: B P
authors.initials: BP
authors.lastname: Damasceno
mesh_terms: D000328:Adult; D001938:Brazil / Q000453:epidemiology; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D020529:Multiple Sclerosis, Relapsing-Remitting / Q000453:epidemiology*; D012189:Retrospective Studies; D012621:Seasons; D013696:Temperature; D014466:Ultraviolet Rays; D055815:Young Adult