title: A retrospective study of seasonal variation in the number of cases diagnosed at a tertiary care tuberculosis hospital.
abstract: OBJECTIVE
  To study the seasonality of tuberculosis (TB) in a tertiary care tuberculosis and respiratory hospital in Delhi.
  
  
  METHODS
  Data from a tertiary care respiratory hospital in south Delhi over a six years period from April 2002 to March 2008 were analysed.
  
  
  RESULTS
  Symptomatics: A total of 192,863 patients were registered newly in the hospital during this period. Maximum number of symptomatic patients reported to the out-patient department during April-June and the minimum during October-December. An increase of about 25% in symptomatics was observed (p < 0.05) in the period from April to June in comparison to October to December. The amplitude of seasonal variation was estimated as 11% of the annual mean symptomatics. Tuberculosis cases: The maximum sputum-positive TB cases were diagnosed during the period from April to June and the number was least during October to December. There was an increase of about 34% in sputum-positive cases (p < 0.001) during the period from April to June against October to December. The amplitude of seasonal variation was estimated as 14.4% of the annual mean smear-positives per quarter. The extra-pulmonary TB (EPTB) cases were the maximum during April-June. Chest symptomatics of all types of TB cases were the lowest in January.
  
  
  CONCLUSIONS
  A seasonal pattern of TB was observed for pulmonary TB and EPTB cases. This information would be useful for administration and managers to take extra care to arrange and provide extra facilities during the peak seasons.
authors.affiliation: L.R.S. Institute of Tuberculosis and Respiratory Diseases, Sri Aurobindo Marg, New Delhi, India. dirlrsi@bol.net.in
authors.forename: D
authors.initials: D
authors.lastname: Behera
authors.forename: P P
authors.initials: PP
authors.lastname: Sharma
mesh_terms: D000328:Adult; D002648:Child; D005260:Female; D006763:Hospitals, Chronic Disease / Q000706:statistics & numerical data*; D006801:Humans; D015994:Incidence; D007194:India / Q000453:epidemiology; D008297:Male; D012189:Retrospective Studies; D012621:Seasons; D014376:Tuberculosis / Q000175:diagnosis* / Q000453:epidemiology