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Incidence and Etiology of Acute Lower Respiratory Tract Infections in Hospitalized Children Younger Than 5 Years in Rural Thailand

Hasan, Reem MD, PhD*†; Rhodes, Julia PhD; Thamthitiwat, Somsak MD, MPH; Olsen, Sonja J. PhD†‡; Prapasiri, Prabda DrPH; Naorat, Sathapana MSc; Chittaganpitch, Malinee MSc§; Henchaichon, Sununta RN; Dejsirilert, Surang MSc§; Srisaengchai, Prasong MSc; Sawatwong, Pongpun MSc; Jorakate, Possawat BSc; Kaewpan, Anek MPH; Fry, Alicia M. MD; Erdman, Dean DrPH; Chuananon, Somchai MD; Amornintapichet, Tussanee MD**; Maloney, Susan A. MD, MHSc† ††; Baggett, Henry C. MD, MPH† ††

The Pediatric Infectious Disease Journal: February 2014 - Volume 33 - Issue 2 - p e45–e52
doi: 10.1097/INF.0000000000000062
Original Studies

Background: Pneumonia remains a leading cause of under-five morbidity and mortality globally. Comprehensive incidence, epidemiologic and etiologic data are needed to update prevention and control strategies.

Methods: We conducted active, population-based surveillance for hospitalized cases of acute lower respiratory tract infections (ALRI) among children <5 years of age in rural Thailand. ALRI cases were systematically sampled for an etiology study that tested nasopharyngeal specimens by polymerase chain reaction; children without ALRI were enrolled as controls from outpatient clinics.

Results: We identified 28,543 hospitalized ALRI cases from 2005 to 2010. Among the 49% with chest radiographs, 63% had findings consistent with pneumonia as identified by 2 study radiologists. The hospitalized ALRI incidence rate was 5772 per 100,000 child-years (95% confidence interval: 5707, 5837) and was higher in boys versus girls (incidence rate ratio 1.38, 95% confidence interval: 1.35–1.41) and in children 6–23 months of age versus other age groups (incidence rate ratio 1.76, 95% confidence interval: 1.69–1.84). Viruses most commonly detected in ALRI cases were respiratory syncytial virus (19.5%), rhinoviruses (18.7%), bocavirus (12.8%) and influenza viruses (8%). Compared with controls, ALRI cases were more likely to test positive for respiratory syncytial virus, influenza, adenovirus, human metapneumovirus and parainfluenza viruses 1 and 3 (P ≤ 0.01 for all). Bloodstream infections, most commonly Streptococcus pneumoniae and nontyphoidal Salmonella, accounted for 1.8% of cases.

Conclusions: Our findings underscore the high burden of hospitalization for ALRI and the importance of viral pathogens among children in Thailand. Interventions targeting viral pathogens coupled with improved diagnostic approaches, especially for bacteria, are critical for better understanding of ALRI etiology, prevention and control.

Supplemental Digital Content is available in the text.

From the *CDC-Hubert Global Health Fellowship, Centers for Disease Control and Prevention, Atlanta, GA; International Emerging Infections Program, Global Disease Detection Regional Center, Thailand Ministry of Public Health–US Centers for Disease Control and Prevention Collaboration, Nonthaburi, Thailand; Influenza Division, Centers for Disease Control and Prevention, Atlanta, GA; §National Institute of Health, Thailand Ministry of Public Health, Nonthaburi, Thailand; Division of Viral Diseases, Centers for Disease Control and Prevention, Atlanta, GA; Nakhon Phanom Provincial Hospital, Nakhon Phanom; **Crown Prince Hospital, Sa Kaeo, Thailand; and ††Division of Global Disease Detection and Emergency Response, Centers for Disease Control and Prevention, Atlanta, GA.

Accepted for publication August 22, 2013.

R. H. was supported by the CDC Foundation for the completion of this work. Support for this project was also provided by Pneumococcal Vaccines Accelerated Development and Introduction Plan, which was funded by the GAVI Alliance and is based at the Johns Hopkins Bloomberg School of Public Health. Support for this project was also provided by the CDC Global Disease Detection Program and the Thailand Ministry of Public Health. The authors have no other funding or conflicts of interest to disclose.

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Address for correspondence: Reem Hasan, Departments of Internal Medicine and Pediatrics, 1500 E Medical Center Dr SPC 5368, Ann Arbor, MI 48109-5376. E-mail:

© 2014 by Lippincott Williams & Wilkins, Inc.