title: Case series study of the clinical profile of H1N1 swine flu influenza.
abstract: OBJECTIVE
  To study the clinical profile of the H1N1 influenza cases attending government hospitals in South India and to study the impact of H1N1 infection on pregnancy outcome.
  
  
  METHODS
  A total number of 442 H1N1 positive patients (198 inpatients and 244 outpatients) from two government hospitals in Chennai, Madras Medical College & Government General Hospital and Institute of Child Health, Egmore were studied retrospectively during a period of 6 months from August 2009 to January 2010.
  
  
  RESULTS
  The rate of reported cases and hospitalization rates was highest among individuals aged 5 to 24 years. H1N1 cases were equally distributed in both the sexes in the adult population In our study 86.92% percent of patients with pandemic H1N1 influenza A met the case definition for influenza like illness (subjective fever plus cough and/or sorethroat). Similar to the western data bronchial asthma, pulmonary tuberculosis were found to risk factors for complications in H1N1 infection. The overall mortality rate was 1.8% and the most common cause of death in patients was due to pneumonia. Ventilator requirement was associated with poor prognosis in H1N1 patients. P value < 0.01. The percentage of persons > 65 years who were affected was far less ie 0.67% which is quite unusual in the case of seasonal flu. H1N1 pnuemonia was found to involve predominantly the lower lobe of lung. (p value < 0.01).The mortality rate among pregnant women with H1N1 infection was 25% and the fetal loss rate was 16.67%. There was an increased risk of H1N1 influenza infection during the third trimester of pregnancy. (p value-0.027).
  
  
  CONCLUSIONS
  Individuals with comorbid conditions, pregnancy were found to be severely affected. Hence individuals with risk factors need to be protected by vaccination.
authors.affiliation: Institute of Internal Medicine, Madras Medical College, Chennai-600003.
authors.forename: A
authors.initials: A
authors.lastname: Puvanalingam
authors.forename: C
authors.initials: C
authors.lastname: Rajendiran
authors.forename: K
authors.initials: K
authors.lastname: Sivasubramanian
authors.forename: S
authors.initials: S
authors.lastname: Ragunanthanan
authors.forename: Sarada
authors.initials: S
authors.lastname: Suresh
authors.forename: S
authors.initials: S
authors.lastname: Gopalakrishnan
mesh_terms: D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000368:Aged; D000818:Animals; D002648:Child; D002675:Child, Preschool; D005260:Female; D006760:Hospitalization / Q000706:statistics & numerical data; D006779:Hospitals, Public; D006801:Humans; D007194:India / Q000453:epidemiology; D053118:Influenza A Virus, H1N1 Subtype / Q000276:immunology / Q000302:isolation & purification*; D007251:Influenza, Human / Q000150:complications / Q000175:diagnosis* / Q000401:mortality* / Q000821:virology; D008875:Middle Aged; D058873:Pandemics; D011014:Pneumonia / Q000150:complications / Q000401:mortality; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000401:mortality* / Q000821:virology; D011256:Pregnancy Outcome; D012189:Retrospective Studies; D012307:Risk Factors; D017678:Sex Distribution; D055815:Young Adult