title: Influenza virus genotypes circulating in and around Lucknow, Uttar Pradesh, India, during post pandemic period, August 2010--September 2012.
abstract: OBJECTIVE
  During the post influenza pandemic period, continuous surveillance of influenza virus and its subtypes is mandatory to help the policy makers to take effective and appropriate decisions. Therefore, this study was planned to determine the pattern of influenza virus activity in context to various meteorological and clinical parameters in and around Lucknow, Uttar Pradesh, India, during post pandemic period August 2010 - September 2012.
  
  
  METHODS
  Nasal swabs/throat swabs/nasopharyngeal aspirates of 2669 patients were collected. One-step real time PCR for detection of influenza virus was done according to the Centers for Disease Control and Prevention (CDC) protocol.
  
  
  RESULTS
  Influenza positivity was 15.8 per cent (423/2669) in symptomatic patients. Of the 423 total positives, 192 (7.2%) were influenza A and 231 (8.7%) were influenza B. Positivity for influenza virus was significantly (P=0.001, OR=2.9, CI=1.9-4.3) higher in patients with Influenza like illness (ILI) (17.4%, 396/2271) than those with severe acute respiratory illness (SARI) (6.8%, 27/398). Influenza A positive samples were subtyped as; pdmH1N1 (67.2%, 129/192) and seasonal H3N2 (32.8%, 63/192). It significantly correlated with monthly mean rainfall, humidity and dew point while atmospheric pressure was inversely related. No significant association was found with temperature and wind speed. Clinical variations were observed between different strains of Influenza virus.
  
  
  CONCLUSIONS
  The findings provide a clear picture of different clinical presentations of various strains of influenza A and B viruses and epidemiology of influenza infection from Lucknow (UP), India. The seasonality of influenza virus infection showed variation in relation to different environmental factors. Pandemic H1N1 caused more systemic infection than seasonal influenza A/H3N2 virus.
authors.forename: Tanushree
authors.initials: T
authors.lastname: Dangi
authors.forename: Bhawana
authors.initials: B
authors.lastname: Jain
authors.forename: Ajay Kumar
authors.initials: AK
authors.lastname: Singh
authors.forename: Madan
authors.initials: M
authors.lastname: Mohan
authors.forename: Mukesh
authors.initials: M
authors.lastname: Dwivedi
authors.forename: J V
authors.initials: JV
authors.lastname: Singh
authors.forename: Rashmi
authors.initials: R
authors.lastname: Kumar
authors.forename: K P
authors.initials: KP
authors.lastname: Singh
authors.forename: M S
authors.initials: MS
authors.lastname: Chaddha
authors.forename: A C
authors.initials: AC
authors.lastname: Mishra
authors.affiliation: Department of Microbiology, King George's Medical University, Lucknow, India.
authors.forename: Amita
authors.initials: A
authors.lastname: Jain
mesh_terms: D062665:Epidemiological Monitoring; D005838:Genotype; D049674:History, 21st Century; D006801:Humans; D007194:India / Q000453:epidemiology; D007251:Influenza, Human / Q000453:epidemiology* / Q000821:virology*; D016017:Odds Ratio; D009975:Orthomyxoviridae / Q000145:classification / Q000235:genetics*; D058873:Pandemics / Q000266:history*; D060888:Real-Time Polymerase Chain Reaction