Community-based pathogen-specific incidence of influenza-like illness due to respiratory viruses in South-central Vietnam in 2009–2012: after a pandemic of influenza A viruses

Abstract Background Influenza-like illness (ILI) is one of the most common illnesses caused by various respiratory viruses and directly or indirectly incurs high expenses to households. However, the pathogen-specific incidence and health-seeking behaviour in communities have not been well described....

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Main Authors: Kensuke Takahashi, Shinya Tsuzuki, Minh Nhat Le, Nguyen Hien Anh, Dang Duc Anh, Koya Ariyoshi, Lay-Myint Yoshida
Format: Article
Language:English
Published: BMC 2025-04-01
Series:Tropical Medicine and Health
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Online Access:https://doi.org/10.1186/s41182-025-00711-x
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author Kensuke Takahashi
Shinya Tsuzuki
Minh Nhat Le
Nguyen Hien Anh
Dang Duc Anh
Koya Ariyoshi
Lay-Myint Yoshida
author_facet Kensuke Takahashi
Shinya Tsuzuki
Minh Nhat Le
Nguyen Hien Anh
Dang Duc Anh
Koya Ariyoshi
Lay-Myint Yoshida
author_sort Kensuke Takahashi
collection DOAJ
description Abstract Background Influenza-like illness (ILI) is one of the most common illnesses caused by various respiratory viruses and directly or indirectly incurs high expenses to households. However, the pathogen-specific incidence and health-seeking behaviour in communities have not been well described. Methods A longitudinal cohort study using a self-recorded health calendar among 1000 households was performed in South-central Vietnam from October 2009 to September 2012. Endemic respiratory viruses in the community were monitored using random sampling in public health clinics (polyclinics). The monthly incidence of specific pathogens was calculated using the Bayesian method. Findings Among 5,016 household members, 3,687 ILI episodes were reported during the study period. The incidence rate of ILI was 21.7 (95% confidence interval 21.0–22.4) per 1,000 person-months for all ages and highest in children under 2 years with 71.6 (64.7–81.8) followed by 2–4 years with 71.3 (65.8–78.2). Rhinovirus had the highest incidence with 22.5 among the age under 2 years, followed by adenovirus and respiratory syncytial virus (RSV) with 12.5 and 9.9, respectively. Most young children sought treatment from clinics and hospitals, whereas most schoolchildren and adults sought treatment from drugstores. RSV outbreaks significantly increase the number of healthcare visits among children under 2 years, but not in older age groups. Interpretation Several surges of ILI were attributed by multiple respiratory viruses. Healthcare seeking patterns were varied among pathogens. Highly transmissible viruses, such as rhinovirus and adenovirus, pose the potential risk of the next pandemic.
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spelling doaj-art-3879a91ccd9242298e52d337ccf4e8bd2025-08-20T02:12:07ZengBMCTropical Medicine and Health1349-41472025-04-0153111110.1186/s41182-025-00711-xCommunity-based pathogen-specific incidence of influenza-like illness due to respiratory viruses in South-central Vietnam in 2009–2012: after a pandemic of influenza A virusesKensuke Takahashi0Shinya Tsuzuki1Minh Nhat Le2Nguyen Hien Anh3Dang Duc Anh4Koya Ariyoshi5Lay-Myint Yoshida6Acute & Critical Care Center, Nagasaki University HospitalDisease Control and Prevention Center, National Center for Global Health and MedicineAntimicrobial Resistance Research Centre, National Institute of Infectious DiseaseDepartment of Bacteriology, National Institute of Hygiene and EpidemiologyDepartment of Bacteriology, National Institute of Hygiene and EpidemiologyDepartment of Clinical Medicine, Institute of Tropical Medicine, Nagasaki UniversityDepartment of Pediatric Infectious Diseases, Institute of Tropical Medicine, Nagasaki UniversityAbstract Background Influenza-like illness (ILI) is one of the most common illnesses caused by various respiratory viruses and directly or indirectly incurs high expenses to households. However, the pathogen-specific incidence and health-seeking behaviour in communities have not been well described. Methods A longitudinal cohort study using a self-recorded health calendar among 1000 households was performed in South-central Vietnam from October 2009 to September 2012. Endemic respiratory viruses in the community were monitored using random sampling in public health clinics (polyclinics). The monthly incidence of specific pathogens was calculated using the Bayesian method. Findings Among 5,016 household members, 3,687 ILI episodes were reported during the study period. The incidence rate of ILI was 21.7 (95% confidence interval 21.0–22.4) per 1,000 person-months for all ages and highest in children under 2 years with 71.6 (64.7–81.8) followed by 2–4 years with 71.3 (65.8–78.2). Rhinovirus had the highest incidence with 22.5 among the age under 2 years, followed by adenovirus and respiratory syncytial virus (RSV) with 12.5 and 9.9, respectively. Most young children sought treatment from clinics and hospitals, whereas most schoolchildren and adults sought treatment from drugstores. RSV outbreaks significantly increase the number of healthcare visits among children under 2 years, but not in older age groups. Interpretation Several surges of ILI were attributed by multiple respiratory viruses. Healthcare seeking patterns were varied among pathogens. Highly transmissible viruses, such as rhinovirus and adenovirus, pose the potential risk of the next pandemic.https://doi.org/10.1186/s41182-025-00711-xILIRespiratory virusIncidenceHealthcare-seeking behaviourInfluenza types A and B
spellingShingle Kensuke Takahashi
Shinya Tsuzuki
Minh Nhat Le
Nguyen Hien Anh
Dang Duc Anh
Koya Ariyoshi
Lay-Myint Yoshida
Community-based pathogen-specific incidence of influenza-like illness due to respiratory viruses in South-central Vietnam in 2009–2012: after a pandemic of influenza A viruses
Tropical Medicine and Health
ILI
Respiratory virus
Incidence
Healthcare-seeking behaviour
Influenza types A and B
title Community-based pathogen-specific incidence of influenza-like illness due to respiratory viruses in South-central Vietnam in 2009–2012: after a pandemic of influenza A viruses
title_full Community-based pathogen-specific incidence of influenza-like illness due to respiratory viruses in South-central Vietnam in 2009–2012: after a pandemic of influenza A viruses
title_fullStr Community-based pathogen-specific incidence of influenza-like illness due to respiratory viruses in South-central Vietnam in 2009–2012: after a pandemic of influenza A viruses
title_full_unstemmed Community-based pathogen-specific incidence of influenza-like illness due to respiratory viruses in South-central Vietnam in 2009–2012: after a pandemic of influenza A viruses
title_short Community-based pathogen-specific incidence of influenza-like illness due to respiratory viruses in South-central Vietnam in 2009–2012: after a pandemic of influenza A viruses
title_sort community based pathogen specific incidence of influenza like illness due to respiratory viruses in south central vietnam in 2009 2012 after a pandemic of influenza a viruses
topic ILI
Respiratory virus
Incidence
Healthcare-seeking behaviour
Influenza types A and B
url https://doi.org/10.1186/s41182-025-00711-x
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