Giuseppe
Emeritus
[Source: PLoS ONE, full text: (LINK). Abstract, edited.]
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Estimation of the Burden of Pandemic(H1N1)2009 in Developing Countries: Experience from a Tertiary Care Center in South India
Mahesh Moorthy<SUP>1</SUP>, Prasanna Samuel<SUP>2</SUP>, John Victor Peter<SUP>4</SUP>, Saranya Vijayakumar<SUP>1</SUP>, Dipika Sekhar<SUP>1</SUP>, Valsan P. Verghese<SUP>3</SUP>, Indira Agarwal<SUP>3</SUP>, Prabhakar D. Moses<SUP>3</SUP>, Kala Ebenezer<SUP>3</SUP>, Ooriapadickal Cherian Abraham<SUP>4</SUP>, Kurien Thomas<SUP>4</SUP>, Prasad Mathews<SUP>4</SUP>, Akhilesh C. Mishra<SUP>6</SUP>, Renu Lal<SUP>7</SUP>, Jayaprakash Muliyil<SUP>5</SUP>, Asha Mary Abraham<SUP>1</SUP><SUP>*</SUP>
<SUP></SUP>
1 Department of Clinical Virology, Christian Medical College, Vellore, Tamil Nadu, India, 2 Departmentof Biostatistics, Christian Medical College, Vellore, Tamil Nadu, India, 3 Department of Child Health, Christian Medical College, Vellore, Tamil Nadu, India, 4 Department of Medicine, Christian Medical College, Vellore, Tamil Nadu, India, 5 Christian Medical College, Vellore, Tamil Nadu, India, 6 National Institute of Virology, Pune, Maharashtra, India, 7 Influenza Division, National Center for Immunization and Resppiratory Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
Abstract
Background
The burden of the pandemic (H1N1) 2009 influenza might be underestimated if detection of the virus is mandated to diagnose infection. Using an alternate approach, we propose that a much higher pandemic burden was experienced in our institution.
Methodology/Principal Findings
Consecutive patients (n = 2588) presenting to our hospital with influenza like illness (ILI) or severe acute respiratory infection (SARI) during a 1-year period (May 2009?April 2010) were prospectively recruited and tested for influenza A by real-time RT-PCR. Analysis of weekly trends showed an 11-fold increase in patients presenting with ILI/SARI during the peak pandemic period when compared with the pre-pandemic period and a significant (P<0.001) increase in SARI admissions during the pandemic period (30?15.9 admissions/week) when compared with pre-pandemic (7?2.5) and post-pandemic periods (5?3.8). However, Influenza A was detected in less than one-third of patients with ILI/SARI [699 (27.0%)]; a majority of these (557/699, 79.7%) were Pandemic (H1N1)2009 virus [A/H1N1/09]. An A/H1N1/09 positive test was correlated with shorter symptom duration prior to presentation (p = 0.03). More ILI cases tested positive for A/H1N1/09 when compared with SARI (27.4% vs. 14.6%, P = 0.037). When the entire study population was considered, A/H1N1/09 positivity was associated with lower risk of hospitalization (p<0.0001) and ICU admission (p = 0.013) suggesting mild self-limiting illness in a majority.
Conclusion/Significance
Analysis of weekly trends of ILI/SARI suggest a higher burden of the pandemic attributable to A/H1N1/09 than estimates assessed by a positive PCR test alone. The study highlights methodological consideration in the estimation of burden of pandemic influenza in developing countries using hospital-based data that may help assess the impact of future outbreaks of respiratory illnesses.
Citation: Moorthy M, Samuel P, Peter JV, Vijayakumar S, Sekhar D, et al. (2012) Estimation of the Burden of Pandemic(H1N1)2009 in Developing Countries: Experience from a Tertiary Care Center in South India. PLoS ONE 7(9): e41507. doi:10.1371/journal.pone.0041507
Editor: Steven J. Drews, University of Calgary & ProvLab Alberta, Canada
Received: February 26, 2012; Accepted: June 22, 2012; Published: September 5, 2012
Copyright: ? 2012 Moorthy et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Funding: This study was funded by the Department of Health and Human Services, USA and the Indian Council of Medical Research, India (Co-operative Agreement No. 5U50/CI024407-05). Reagents for testing were in addition supplied by the National Institute of Virology, Pune, India. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Competing interests: The authors have declared that no competing interests exist.
* E-mail: asha_ma@cmcvellore.ac.in
-Mahesh Moorthy<SUP>1</SUP>, Prasanna Samuel<SUP>2</SUP>, John Victor Peter<SUP>4</SUP>, Saranya Vijayakumar<SUP>1</SUP>, Dipika Sekhar<SUP>1</SUP>, Valsan P. Verghese<SUP>3</SUP>, Indira Agarwal<SUP>3</SUP>, Prabhakar D. Moses<SUP>3</SUP>, Kala Ebenezer<SUP>3</SUP>, Ooriapadickal Cherian Abraham<SUP>4</SUP>, Kurien Thomas<SUP>4</SUP>, Prasad Mathews<SUP>4</SUP>, Akhilesh C. Mishra<SUP>6</SUP>, Renu Lal<SUP>7</SUP>, Jayaprakash Muliyil<SUP>5</SUP>, Asha Mary Abraham<SUP>1</SUP><SUP>*</SUP>
<SUP></SUP>
1 Department of Clinical Virology, Christian Medical College, Vellore, Tamil Nadu, India, 2 Departmentof Biostatistics, Christian Medical College, Vellore, Tamil Nadu, India, 3 Department of Child Health, Christian Medical College, Vellore, Tamil Nadu, India, 4 Department of Medicine, Christian Medical College, Vellore, Tamil Nadu, India, 5 Christian Medical College, Vellore, Tamil Nadu, India, 6 National Institute of Virology, Pune, Maharashtra, India, 7 Influenza Division, National Center for Immunization and Resppiratory Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
Abstract
Background
The burden of the pandemic (H1N1) 2009 influenza might be underestimated if detection of the virus is mandated to diagnose infection. Using an alternate approach, we propose that a much higher pandemic burden was experienced in our institution.
Methodology/Principal Findings
Consecutive patients (n = 2588) presenting to our hospital with influenza like illness (ILI) or severe acute respiratory infection (SARI) during a 1-year period (May 2009?April 2010) were prospectively recruited and tested for influenza A by real-time RT-PCR. Analysis of weekly trends showed an 11-fold increase in patients presenting with ILI/SARI during the peak pandemic period when compared with the pre-pandemic period and a significant (P<0.001) increase in SARI admissions during the pandemic period (30?15.9 admissions/week) when compared with pre-pandemic (7?2.5) and post-pandemic periods (5?3.8). However, Influenza A was detected in less than one-third of patients with ILI/SARI [699 (27.0%)]; a majority of these (557/699, 79.7%) were Pandemic (H1N1)2009 virus [A/H1N1/09]. An A/H1N1/09 positive test was correlated with shorter symptom duration prior to presentation (p = 0.03). More ILI cases tested positive for A/H1N1/09 when compared with SARI (27.4% vs. 14.6%, P = 0.037). When the entire study population was considered, A/H1N1/09 positivity was associated with lower risk of hospitalization (p<0.0001) and ICU admission (p = 0.013) suggesting mild self-limiting illness in a majority.
Conclusion/Significance
Analysis of weekly trends of ILI/SARI suggest a higher burden of the pandemic attributable to A/H1N1/09 than estimates assessed by a positive PCR test alone. The study highlights methodological consideration in the estimation of burden of pandemic influenza in developing countries using hospital-based data that may help assess the impact of future outbreaks of respiratory illnesses.
Citation: Moorthy M, Samuel P, Peter JV, Vijayakumar S, Sekhar D, et al. (2012) Estimation of the Burden of Pandemic(H1N1)2009 in Developing Countries: Experience from a Tertiary Care Center in South India. PLoS ONE 7(9): e41507. doi:10.1371/journal.pone.0041507
Editor: Steven J. Drews, University of Calgary & ProvLab Alberta, Canada
Received: February 26, 2012; Accepted: June 22, 2012; Published: September 5, 2012
Copyright: ? 2012 Moorthy et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Funding: This study was funded by the Department of Health and Human Services, USA and the Indian Council of Medical Research, India (Co-operative Agreement No. 5U50/CI024407-05). Reagents for testing were in addition supplied by the National Institute of Virology, Pune, India. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Competing interests: The authors have declared that no competing interests exist.
* E-mail: asha_ma@cmcvellore.ac.in
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