title: Epidemiology and etiology of influenza-like-illness in households in Vietnam; it's not all about the kids!
abstract: Household studies provide opportunities to understand influenza-like-illness (ILI) transmission, but data from (sub)tropical developing countries are scarce.
  
  
  
  To determine the viral etiology and epidemiology of ILI in households.
  
  
  
  ILI was detected by active case finding amongst a cohort of 263 northern Vietnam households between 2008 and 2013. Health workers collected nose and throat swabs for virus detection by multiplex real-time RT-PCR.
  
  
  
  ILI was detected at least once in 219 (23.7%) of 945 household members. 271 (62.3%) of 435 nose/throat swabs were positive for at least one of the 15 viruses tested. Six viruses predominated amongst positive swabs: Rhinovirus (28%), Influenza virus (17%), Coronavirus (8%), Enterovirus (5%), Respiratory syncytial virus (3%), Metapneumovirus virus (2.5%) and Parainfluenza virus 3 (1.8%). There was no clear seasonality, but 78% of episodes occurred in Winter/Spring for Influenza compared to 32% for Rhinovirus. Participants, on average, suffered 0.49 ILI, and 0.29 virus-positive ILI episodes, with no significant effects of gender, age, or household size. In contrast to US and Australian community studies, the frequency of ILI decreased as the number of household members aged below 5 years increased (p=0.006).
  
  
  
  The findings indicate the need for tailored ILI control strategies, and for better understanding of how local childcare practices and seasonality may influence transmission and the role of children.
authors.affiliation: Oxford University Clinical Research Unit and Wellcome Trust Major Overseas Programme, Vietnam.
authors.forename: Diep Ngoc Thi
authors.initials: DNT
authors.lastname: Nguyen
authors.affiliation: National Institute of Hygiene and Epidemiology, Hanoi, Vietnam.
authors.forename: Le Quynh
authors.initials: LQ
authors.lastname: Mai
authors.affiliation: Oxford University Clinical Research Unit and Wellcome Trust Major Overseas Programme, Vietnam; Center for Tropical Medicine, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK.
authors.forename: Juliet E
authors.initials: JE
authors.lastname: Bryant
authors.affiliation: National Institute of Hygiene and Epidemiology, Hanoi, Vietnam.
authors.forename: Nguyen Le Khanh
authors.initials: NLK
authors.lastname: Hang
authors.affiliation: Oxford University Clinical Research Unit and Wellcome Trust Major Overseas Programme, Vietnam.
authors.forename: Le Nguyen Minh
authors.initials: LNM
authors.lastname: Hoa
authors.affiliation: Oxford University Clinical Research Unit and Wellcome Trust Major Overseas Programme, Vietnam; Center for Tropical Medicine, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK.
authors.forename: Behzad
authors.initials: B
authors.lastname: Nadjm
authors.affiliation: National Institute of Hygiene and Epidemiology, Hanoi, Vietnam.
authors.forename: Pham Quang
authors.initials: PQ
authors.lastname: Thai
authors.affiliation: National Institute of Hygiene and Epidemiology, Hanoi, Vietnam.
authors.forename: Tran Nhu
authors.initials: TN
authors.lastname: Duong
authors.affiliation: National Institute of Hygiene and Epidemiology, Hanoi, Vietnam.
authors.forename: Dang Duc
authors.initials: DD
authors.lastname: Anh
authors.affiliation: Oxford University Clinical Research Unit and Wellcome Trust Major Overseas Programme, Vietnam; Center for Tropical Medicine, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK.
authors.forename: Peter
authors.initials: P
authors.lastname: Horby
authors.affiliation: Oxford University Clinical Research Unit and Wellcome Trust Major Overseas Programme, Vietnam; Center for Tropical Medicine, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK.
authors.forename: H Rogier
authors.initials: HR
authors.lastname: van Doorn
authors.affiliation: Oxford University Clinical Research Unit and Wellcome Trust Major Overseas Programme, Vietnam; Department of Medical Microbiology, Radboudumc, Nijmegen, Netherlands.
authors.forename: Heiman F L
authors.initials: HFL
authors.lastname: Wertheim
authors.affiliation: Oxford University Clinical Research Unit and Wellcome Trust Major Overseas Programme, Vietnam; The University of Melbourne, Peter Doherty Institute for Infection and Immunity, Department of Microbiology and Immunology, Parkville, Victoria, Australia. Electronic address: annette.fox@unimelb.edu.au.
authors.forename: Annette
authors.initials: A
authors.lastname: Fox
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D005191:Family Characteristics; D005192:Family Health; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D060885:Multiplex Polymerase Chain Reaction; D009296:Nasal Cavity / Q000821:virology; D010614:Pharynx / Q000821:virology; D060888:Real-Time Polymerase Chain Reaction; D012141:Respiratory Tract Infections / Q000453:epidemiology* / Q000209:etiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014744:Vietnam / Q000453:epidemiology; D014777:Virus Diseases / Q000453:epidemiology* / Q000209:etiology*; D014780:Viruses / Q000145:classification / Q000302:isolation & purification*; D055815:Young Adult
keywords: Active case finding; Cohort; Household transmission; Influenza-like-illness; Respiratory viruses; Vietnam