Case series study of the clinical profile of H1N1 swine flu influenza.

OBJECTIVES: 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.

MATERIALS AND 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.