A pilot study of seroprevalence of influenza virus type A in Vellore, south India
Michael, J.S.; Sridharan, G.
Indian Journal of Medical Research 115: 173-175
2002
ISSN/ISBN: 0019-5340 PMID: 12362555 Document Number: 542936
Background and objectives: Influenza virus type A is active in many regions of the world. However, information from many parts of India is sparse. Hence we carried out a serological study on the prevalence of antibodies to influenza virus type A in Vellore, south India. Methods: Antibodies to influenza virus type A (H1N1 and H3N2) were detected using a haemagglutination inhibition (HI) test. A total of 186 individuals comprising healthy blood donors and laboratory workers were tested. Results: The titres ranged from < 20 - 2580, with a high geometric mean titre (GMT) of 200 for H3N2 and < 20-1280 with a GMT of 74 for H1N1 serotype of influenza virus type A. Among the 186 serum samples tested, 175 (94.04%) were positive for H1N1 and 185 (99.5%) for H3N2 with a titre > 20. Interpretation and conclusion: The prevalence of elevated level of antibodies in the individuals indicates a high exposure to the influenza A virus in our population with a seropositive status in 99.5 per cent of the individuals tested. Virus surveillance needs to be instituted in different parts of the country to monitor the activity of these viruses.