Influenza A (H1N1) Virus Outbreak in the Districts of Chhattisgarh: A Cross-Sectional Study

Background The H1N1 flu is a subtype of the influenza A virus, also known as the swine flu. An entirely new strain of the H1N1 virus started sickening people in the 2009-2010 flu season. It was a novel influenza virus combination that can infect humans, pigs, and birds. It was frequently referred to as the "swine flu." The virus may be able to spread for a little while longer in children and individuals with compromised immune systems. Objective The objective is to investigate the outbreaks of H1N1 among young adults in the Bastar District of Chhattisgarh. Methods Collection of the blood samples of 342 individuals between December 2015 and November 2017 was done. Thirty-one cases of Influenza A (H1N1) PDM09 virus infection were identified and confirmed. The molecular relationship between viruses is identified by the real-time polymerase chain reaction (RT-PCR) method. Result The majority of samples (n=13) were sourced from Raipur Medical College, followed by contributions from Durg District Hospital (n=5), Raigarh Medical College (n=4), Rajnandgaon District Hospital (n=3), Jagdalpur Medical College (n=2), Bilaspur Medical College (n=2), and smaller contributions from Dhamtari District Hospital and Gariyabandh Primary Health Care. Among these, 31 samples tested positive for Influenza A (H1N1) PDM 2009 virus, with a slightly higher prevalence among 19 female patients. Age-wise distribution revealed higher proportions of positive cases in the age groups of 0-10 years, 31-40 years, and 21-30 years. In the molecular analysis, 154 samples showed no target amplification, while 125 samples exhibited amplification of only Influenza A without subtype (H1) amplification. Remarkably, 31 patients who tested positive for Influenza A (H1N1) died from the virus; most of the deaths were in children under five and middle-aged adults. Conclusion The detection of Influenza A (H1N1) PDM 2009 virus, especially among females, indicates its persistent circulation. Positive cases were prevalent among younger and middle-aged individuals. Molecular analysis showed subtype variations, with significant fatalities observed in children under five and middle-aged adults, emphasizing the severity of the virus across different age groups. It is advised that in order to keep Indian influenza surveillance up to date and robust, more epidemiological data should be gathered, along with information on risk factors like immunization status, hospitalization, and mortality rates should be estimated, and influenza case subtyping should be improved.