Abstract

Background: Recently H1N1 infection has posed a serious public health challenge in India. People belonging to all age groups including children and adolescents have fallen prey to this infection in 2009 and 2015. Interventions focused on climatic factors could play a role in mitigating the public health impact of future H1N1 influenza pandemics. Determinants of H1N1 infection should be studied for getting prepared for control of future epidemics.

Objectives: To study the trends of the H1N1 infection over the last 5 years in both Mumbai city and the tertiary care hospital in the city (2011-2015) and to study the effect of temperature, rainfall, and humidity on the trends of H1N1 infection.

Materials and Methods: A retrospective analysis of suspected and confirmed cases of H1N1 influenza infection in a tertiary care hospital in Mumbai from February 2015 to December 2015. Analysis of secondary data of H1N1 cases at Mumbai from January 2011 to December 2015 was also done.

Results: The H1N1 cases were highest in the year 2015 from 2011 to 2015. Total numbers of 707 respiratory cases reported in the tertiary care hospital were tested for H1N1 in the year 2015. Proportion of positive H1N1 cases was more among female (63.33%) than male (36.67%). A group of 16-30 years age was most affected. The case fatality rate of H1N1 was 6.67% in the year 2015. Cough (67.77%) was the most common symptom. The peak of cases was observed in the month of March followed by August. Data analysis showed no significant correlation between H1N1 cases and climatic factors such as rainfall, temperature, and humidity.

Conclusion: This study proves the occurrence of an epidemic like situation of H1N1 in 2015 but does not show any relation with environmental factors such as rainfall, temperature, and humidity with occurrence of H1N1 cases.

Key words: H1N1; Trends; Case Positivity Rate; Case Fatality Rate, Climatic Factors