Abstract
The Influenza A H1N1 virus is a highly contagious pathogen which caused the 2009 influenza pandemic. Recently an outbreak of Influenza A H1N1 occurred in the Western Rajasthan region of India. A retrospective, descriptive study was carried out to describe the epidemiological profile and clinical outcome of all H1N1 cases that occurred in Western Rajasthan during this outbreak. The Epidemiological profiles of all H1N1 cases were analyzed with reference to age, sex and time wise distribution of morbidity and mortality. The study reveals that during outbreak a total of 1372 suspected patients were tested for Influenza A H1N1, out of which 24.6% (157) were found to be positive for the disease. 27.2% of all suspected and 33.2% of all positive cases were seen during the month of January 2013. 70.1% were seen amongst the age group of 15 to 45 years. 67.4% cases were seen in females. Most cases (215) and deaths (28) were seen in Jodhpur district. 58 patients expired with an overall case fatality ratio of 19.1%. Most of the deaths were seen in younger patients (15-45 years) with a case fatality ratio of 20.2%. 53.4% cases had expired within 48 hour of admission. 37.6% of cases and 39.4% of deaths occurred in pregnant women.In conclusion, the A (H1N1) pdm09 virus is still active two years after the 2009 pandemic. In fact, it has become a ubiquitous seasonal virus in the region. Complications are common and life threatening. Similar to H1N1 pandemic 2009, the incidence and mortality in this outbreak was higher in young.

Key words: H1N1, Pandemic, RT-PCR, Swine flu, Western Rajasthan