Pandemic influenza A(H1N1)pdm09: An unrecognized cause of mortality in children in Pakistan

Abstract

The role of influenza virus as a cause of child mortality in South Asia is under-recognized. We aimed to determine the incidence and case fatality rate of influenza A(H1N1)pdm09 infections in hospitalized children in Karachi, Pakistan. Children less than 5 y old admitted with respiratory illnesses to the Aga Khan University Hospital, Karachi, from 17 August 2009 to 16 September 2011, were tested for influenza A(H1N1)pdm09 using a real-time reverse transcriptase polymerase chain reaction. Out of 2650 children less than 5 y old admitted with a respiratory illness during the study period, 812 (31%) were enrolled. Influenza A(H1N1)pdm09 virus was detected in 27 (3.3%) children. There were 4 deaths in children who tested positive for influenza A(H1N1)pdm09 (case fatality rate of 15%). Children with influenza A(H1N1)pdm09 were 5 times more likely to be admitted or transferred to the intensive care unit, 5.5 times more likely to be intubated, and 12.9 times more likely to die as compared to children testing negative for influenza A(H1N1)pdm09.

Keywords::

• Influenza
• children
• pneumonia
• Pakistan
• H1N1

Acknowledgements

The authors gratefully acknowledge the help of Calvin Akhtar, Romena Qazi, Beenish Hanif, Sahr Sami, Urooj Iftikhar, Momin Kazi, and Zulfiqar Bhutta of Aga Khan University, Pakistan; Uzma Aamir and Sohail Zaidi of NIH, Pakistan; Sten Vermund and John Williams of Vanderbilt University, USA; and Dean Erdman of CDC, USA. We are also particularly grateful to the faculty, residents, and staff of the Department of Pediatrics at Aga Khan University for their facilitation, and to the patients and their families for participating in this study. This study was supported by grant 1R01TW008126-01 from FIC/NIH, titled ‘Burden of Influenza and RSV in Children in Pakistan’ (PI Asad Ali). For data storage and management, Research Electronic Data Capture (REDCAP) software was used, which is supported by research grant 1UL1RR024975 from NCRR/NIH. The laboratory training of Dr Ali was partially supported by grant D43TW007585 from FIC/NIH.

Declaration of interest: None.