An outbreak of influenza A(H3N2) in Alappuzha district, Kerala, India, in 2011

  • Sam Peter National Institute of Virology (NIV), Kerala Unit, Medical College Hospital Complex, Alappuzha, Kerala, India
  • Anukumar Balakrishnan National Institute of Virology (NIV), Kerala Unit, Medical College Hospital Complex, Alappuzha, Kerala, India
  • Varsha A Potdar National Institute of Virology (NIV), Pune, India
  • Mandeep S Chadha National Institute of Virology (NIV), Pune, India
  • Santhosh M Jadhav National Institute of Virology (NIV), Pune, India
Keywords: India, influenza A(H3N2), influenza-like illness, influenza virus, Kerala, outbreak

Abstract

Introduction: Influenza is an RNA virus that belongs to the Orthomyxoviridae family. It causes a highly contagious acute respiratory illness, has been recognized since ancient times, and is a major health threat throughout the world. An outbreak of influenza-like illness (ILI) was reported from Alappuzha district of Kerala State between late June and July 2011. This investigation was conducted to determine the clinical picture, causative agents, and epidemiological characteristics of the illness.

Methodology: The World Health Organization (WHO)’s case definition for ILI was followed throughout the investigation. Nasal or throat swabs were collected from 204 suspected patients. Real-time reverse transcription polymerase chain reaction (RT-PCR)-based diagnosis was performed to detect influenza A and B viruses and their subtypes. Madin-Darby canine kidney (MDCK) cell line was used for virus isolation. One-step RT-PCR was performed to amplify the HA1 gene of influenza A(H3N2). The amplicons for the HA1 gene of influenza A(H3N2) were sequenced, and phylogenetic analysis was done.

Results: Analysis of the data revealed that 96 (47.05%) of the 204 respiratory specimens collected were influenza A(H3N2) and only 6 (2.94%) were A(H1N1)pdm09. Phylogenetic analysis revealed that the isolated A(H3N2) was closely related to the 2012–2013 northern hemisphere vaccine strain (A/Victoria/361/2011/H3N2).

Conclusions: An influenza A(H3N2) outbreak was confirmed in Alappuzha district of Kerala state with a co-circulation of A(H1N1)pdm09. No substantial difference in the sequence was observed in the etiological agent, and the virus was found to be sensitive to oseltamivir.

Author Biographies

Sam Peter, National Institute of Virology (NIV), Kerala Unit, Medical College Hospital Complex, Alappuzha, Kerala, India

National Institute of Virology Kerala unit

The author has done laboratory work and written the manuscript

Anukumar Balakrishnan, National Institute of Virology (NIV), Kerala Unit, Medical College Hospital Complex, Alappuzha, Kerala, India

Officer In Charge & Scientist

National Institute of Virology Kerala unit

Varsha A Potdar, National Institute of Virology (NIV), Pune, India

Human Influenza Group

National institute of Virology-Pune

The author has done the sequencing work

Mandeep S Chadha, National Institute of Virology (NIV), Pune, India

Human Influenza Virus group

National Institute of Virology -Pune

The author guided us for field work

Santhosh M Jadhav, National Institute of Virology (NIV), Pune, India

Bioinformatics and Data management group

National insitute of Virology-Pune

The author has done phylogenitic analysis

Published
2015-04-15
How to Cite
1.
Peter S, Balakrishnan A, Potdar VA, Chadha MS, Jadhav SM (2015) An outbreak of influenza A(H3N2) in Alappuzha district, Kerala, India, in 2011. J Infect Dev Ctries 9:362-367. doi: 10.3855/jidc.5723
Section
Outbreak