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PLoS ONE. Incidence and Epidemiology of Hospitalized Influenza Cases in Rural Thailand during the Influenza A (H1N1)pdm09 Pandemic, 2009?2010
[Source: PLoS ONE, full text: (LINK). Abstract, edited.]
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Incidence and Epidemiology of Hospitalized Influenza Cases in Rural Thailand during the Influenza A (H1N1)pdm09 Pandemic, 2009?2010
Henry C. Baggett<SUP>1</SUP><SUP>,</SUP><SUP>2</SUP><SUP>*</SUP>, Malinee Chittaganpitch<SUP>3</SUP>, Somsak Thamthitiwat<SUP>1</SUP>, Prabda Prapasiri<SUP>1</SUP>, Sathapana Naorat<SUP>1</SUP>, Pongpun Sawatwong<SUP>1</SUP>, Darunee Ditsungnoen<SUP>4</SUP>, Sonja J. Olsen<SUP>1</SUP><SUP>,</SUP><SUP>5</SUP>, James M. Simmerman<SUP>1</SUP>, Prasong Srisaengchai<SUP>1</SUP>, Somrak Chantra<SUP>6</SUP>, Leonard F. Peruski<SUP>1</SUP><SUP>,</SUP><SUP>2</SUP>, Pathom Sawanpanyalert<SUP>3</SUP>, Susan A. Maloney<SUP>1</SUP><SUP>,</SUP><SUP>2</SUP>, Pasakorn Akarasewi<SUP>7</SUP>
<SUP></SUP>
1 International Emerging Infections Program, Thailand Ministry of Public Health (MOPH) ? U.S. Centers for Disease Control and Prevention Collaboration, Nonthaburi, Thailand, 2 Global Disease Detection Branch, Global Disease Detection and Emergency Response Division, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America, 3 National Institute of Health, MOPH, Nonthaburi, Thailand, 4 Nakhon Phanom Provincial Health Office, Nakhon Phanom, Thailand, 5 Influenza Division, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America, 6 Sa Kaeo Provincial Health Office, MOPH, Sa Kaeo, Thailand, 7 Bureau of Epidemiology, MOPH, Nonthaburi, Thailand
Abstract
Background
Data on the burden of the 2009 influenza pandemic in Asia are limited. Influenza A(H1N1)pdm09 was first reported in Thailand in May 2009. We assessed incidence and epidemiology of influenza-associated hospitalizations during 2009?2010.
Methods
We conducted active, population-based surveillance for hospitalized cases of acute lower respiratory infection (ALRI) in all 20 hospitals in two rural provinces. ALRI patients were sampled 1:2 for participation in an etiology study in which nasopharyngeal swabs were collected for influenza virus testing by PCR.
Results
Of 7,207 patients tested, 902 (12.5%) were influenza-positive, including 190 (7.8%) of 2,436 children aged <5 years; 86% were influenza A virus (46% A(H1N1)pdm09, 30% H3N2, 6.5% H1N1, 3.5% not subtyped) and 13% were influenza B virus. Cases of influenza A(H1N1)pdm09 first peaked in August 2009 when 17% of tested patients were positive. Subsequent peaks during 2009 and 2010 represented a mix of influenza A(H1N1)pdm09, H3N2, and influenza B viruses. The estimated annual incidence of hospitalized influenza cases was 136 per 100,000, highest in ages <5 years (477 per 100,000) and >75 years (407 per 100,000). The incidence of influenza A(H1N1)pdm09 was 62 per 100,000 (214 per 100,000 in children <5 years). Eleven influenza-infected patients required mechanical ventilation, and four patients died, all adults with influenza A(H1N1)pdm09 (1) or H3N2 (3).
Conclusions
Influenza-associated hospitalization rates in Thailand during 2009?10 were substantial and exceeded rates described in western countries. Influenza A(H1N1)pdm09 predominated, but H3N2 also caused notable morbidity. Expanded influenza vaccination coverage could have considerable public health impact, especially in young children.
Citation: Baggett HC, Chittaganpitch M, Thamthitiwat S, Prapasiri P, Naorat S, et al. (2012) Incidence and Epidemiology of Hospitalized Influenza Cases in Rural Thailand during the Influenza A (H1N1)pdm09 Pandemic, 2009?2010. PLoS ONE 7(11): e48609. doi:10.1371/journal.pone.0048609
Editor: Edward Goldstein, Harvard School of Public Health, United States of America
Received: May 28, 2012; Accepted: September 27, 2012; Published: November 6, 2012
This is an open-access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose. The work is made available under the Creative Commons CC0 public domain dedication.
Funding: This research was funded by the U.S. Centers for Disease Control and Prevention. The funders had a role in study design, data collection and analysis, decision to publish, and preparation of the manuscript.
Competing interests: One co-author (JMS) is currently employed by Sanofi Pasteur. All other co-authors have declared that no competing interests exist. This does not alter the authors' adherence to all the PLOS ONE policies on sharing data and materials.
* E-mail: hbaggett@cdc.gov
-Henry C. Baggett<SUP>1</SUP><SUP>,</SUP><SUP>2</SUP><SUP>*</SUP>, Malinee Chittaganpitch<SUP>3</SUP>, Somsak Thamthitiwat<SUP>1</SUP>, Prabda Prapasiri<SUP>1</SUP>, Sathapana Naorat<SUP>1</SUP>, Pongpun Sawatwong<SUP>1</SUP>, Darunee Ditsungnoen<SUP>4</SUP>, Sonja J. Olsen<SUP>1</SUP><SUP>,</SUP><SUP>5</SUP>, James M. Simmerman<SUP>1</SUP>, Prasong Srisaengchai<SUP>1</SUP>, Somrak Chantra<SUP>6</SUP>, Leonard F. Peruski<SUP>1</SUP><SUP>,</SUP><SUP>2</SUP>, Pathom Sawanpanyalert<SUP>3</SUP>, Susan A. Maloney<SUP>1</SUP><SUP>,</SUP><SUP>2</SUP>, Pasakorn Akarasewi<SUP>7</SUP>
<SUP></SUP>
1 International Emerging Infections Program, Thailand Ministry of Public Health (MOPH) ? U.S. Centers for Disease Control and Prevention Collaboration, Nonthaburi, Thailand, 2 Global Disease Detection Branch, Global Disease Detection and Emergency Response Division, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America, 3 National Institute of Health, MOPH, Nonthaburi, Thailand, 4 Nakhon Phanom Provincial Health Office, Nakhon Phanom, Thailand, 5 Influenza Division, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America, 6 Sa Kaeo Provincial Health Office, MOPH, Sa Kaeo, Thailand, 7 Bureau of Epidemiology, MOPH, Nonthaburi, Thailand
Abstract
Background
Data on the burden of the 2009 influenza pandemic in Asia are limited. Influenza A(H1N1)pdm09 was first reported in Thailand in May 2009. We assessed incidence and epidemiology of influenza-associated hospitalizations during 2009?2010.
Methods
We conducted active, population-based surveillance for hospitalized cases of acute lower respiratory infection (ALRI) in all 20 hospitals in two rural provinces. ALRI patients were sampled 1:2 for participation in an etiology study in which nasopharyngeal swabs were collected for influenza virus testing by PCR.
Results
Of 7,207 patients tested, 902 (12.5%) were influenza-positive, including 190 (7.8%) of 2,436 children aged <5 years; 86% were influenza A virus (46% A(H1N1)pdm09, 30% H3N2, 6.5% H1N1, 3.5% not subtyped) and 13% were influenza B virus. Cases of influenza A(H1N1)pdm09 first peaked in August 2009 when 17% of tested patients were positive. Subsequent peaks during 2009 and 2010 represented a mix of influenza A(H1N1)pdm09, H3N2, and influenza B viruses. The estimated annual incidence of hospitalized influenza cases was 136 per 100,000, highest in ages <5 years (477 per 100,000) and >75 years (407 per 100,000). The incidence of influenza A(H1N1)pdm09 was 62 per 100,000 (214 per 100,000 in children <5 years). Eleven influenza-infected patients required mechanical ventilation, and four patients died, all adults with influenza A(H1N1)pdm09 (1) or H3N2 (3).
Conclusions
Influenza-associated hospitalization rates in Thailand during 2009?10 were substantial and exceeded rates described in western countries. Influenza A(H1N1)pdm09 predominated, but H3N2 also caused notable morbidity. Expanded influenza vaccination coverage could have considerable public health impact, especially in young children.
Citation: Baggett HC, Chittaganpitch M, Thamthitiwat S, Prapasiri P, Naorat S, et al. (2012) Incidence and Epidemiology of Hospitalized Influenza Cases in Rural Thailand during the Influenza A (H1N1)pdm09 Pandemic, 2009?2010. PLoS ONE 7(11): e48609. doi:10.1371/journal.pone.0048609
Editor: Edward Goldstein, Harvard School of Public Health, United States of America
Received: May 28, 2012; Accepted: September 27, 2012; Published: November 6, 2012
This is an open-access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose. The work is made available under the Creative Commons CC0 public domain dedication.
Funding: This research was funded by the U.S. Centers for Disease Control and Prevention. The funders had a role in study design, data collection and analysis, decision to publish, and preparation of the manuscript.
Competing interests: One co-author (JMS) is currently employed by Sanofi Pasteur. All other co-authors have declared that no competing interests exist. This does not alter the authors' adherence to all the PLOS ONE policies on sharing data and materials.
* E-mail: hbaggett@cdc.gov
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