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Differing clinical characteristics between influenza strains among young healthy adults in the tropics

Yap, Jonathan; Tan, Chi; Cook, Alex R; Loh, Jin; Tambyah, Paul A; Tan, Boon; Lee, Vernon J

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BACKGROUND Influenza infections may result in different clinical presentations. This study aims to determine the clinical differences between circulating influenza strains in a young healthy adult population in the tropics. METHODS A febrile respiratory illness (FRI) (fever ≥ 37.5°C with cough and/or sore throat) surveillance program was started in 4 large military camps in Singapore on May 2009. Personnel with FRI who visited the camp clinics from 11 May 2009 to 25 June 2010 were recruited....[Show more]

dc.contributor.authorYap, Jonathan
dc.contributor.authorTan, Chi
dc.contributor.authorCook, Alex R
dc.contributor.authorLoh, Jin
dc.contributor.authorTambyah, Paul A
dc.contributor.authorTan, Boon
dc.contributor.authorLee, Vernon J
dc.date.accessioned2016-01-11T01:57:05Z
dc.date.available2016-01-11T01:57:05Z
dc.identifier.issn1471-2334
dc.identifier.urihttp://hdl.handle.net/1885/95302
dc.description.abstractBACKGROUND Influenza infections may result in different clinical presentations. This study aims to determine the clinical differences between circulating influenza strains in a young healthy adult population in the tropics. METHODS A febrile respiratory illness (FRI) (fever ≥ 37.5°C with cough and/or sore throat) surveillance program was started in 4 large military camps in Singapore on May 2009. Personnel with FRI who visited the camp clinics from 11 May 2009 to 25 June 2010 were recruited. Nasal washes and interviewer-administered questionnaires on demographic information and clinical features were obtained from consenting participants. All personnel who tested positive for influenza were included in the study. Overall symptom load was quantified by counting the symptoms or signs, and differences between strains evaluated using linear models. RESULTS There were 434 (52.9%) pandemic H1N1-2009, 58 (7.1%) seasonal H3N2, 269 (32.8%) influenza B, and 10 (1.2%) seasonal H1N1 cases. Few seasonal influenza A (H1N1) infections were detected and were therefore excluded from analyses, together with undetermined influenza subtypes (44 (1.5%)), or more than 1 co-infecting subtype (6 (0.2%)). Pandemic H1N1-2009 cases had significantly fewer symptoms or signs (mean 7.2, 95%CI 6.9-7.4, difference 1.6, 95%CI 1.2-2.0, p < 0.001) than the other two subtypes (mean 8.7, 95%CI 8.5-9.0). There were no statistical differences between H3N2 and influenza B (p = 0.58). Those with nasal congestion, rash, eye symptoms, injected pharynx or fever were more likely to have H3N2; and those with sore throat, fever, injected pharynx or rhinorrhoea were more likely to have influenza B than H1N1-2009. CONCLUSIONS Influenza cases have different clinical presentations in the young adult population. Pandemic H1N1 influenza cases had fewer and milder clinical symptoms than seasonal influenza. As we only included febrile cases and had no information on the proportion of afebrile infections, further research is needed to confirm whether the relatively milder presentation of pandemic versus seasonal influenza infections applies to all infections or only febrile illnesses.
dc.description.sponsorshipThe work was supported by a Singapore Ministry of Defence funded operational research program.
dc.publisherBioMed Central
dc.rights© Yap et al; BioMed Central Ltd. 2012 This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://​creativecommons.​org/​licenses/​by/​2.​0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
dc.sourceBMC Infectious Diseases
dc.subjectfemale
dc.subjectfever
dc.subjecthumans
dc.subjectinfluenza a virus, h1n1 subtype
dc.subjectinfluenza a virus, h3n2 subtype
dc.subjectinfluenza, human
dc.subjectmale
dc.subjectmilitary personnel
dc.subjectnose
dc.subjectpharyngitis
dc.subjectquestionnaires
dc.subjectsingapore
dc.subjecttropical climate
dc.subjectyoung adult
dc.titleDiffering clinical characteristics between influenza strains among young healthy adults in the tropics
dc.typeJournal article
local.description.notesImported from ARIES
local.identifier.citationvolume12
dc.date.issued2012-01-20
local.identifier.absfor119999
local.identifier.ariespublicationf5625xPUB3095
local.publisher.urlhttp://www.biomedcentral.com/
local.type.statusPublished Version
local.contributor.affiliationYap, Jonathan, Singapore Ministry of Defence, Singapore
local.contributor.affiliationTan, Chi Hsien, Ministry of Defence Singapore, Singapore
local.contributor.affiliationCook, Alex R, National University of Singapore, Singapore
local.contributor.affiliationLoh, Jin Phang, DSO National Laboratories, Singapore
local.contributor.affiliationTambyah, Paul Ananth, National University Hospital, Singapore
local.contributor.affiliationTan, Boon Huan, DSO National Laboratories, Singapore
local.contributor.affiliationLee, Vernon, College of Medicine, Biology and Environment, CMBE Research School of Population Health, Natl Centre for Epidemiology & Population Health, The Australian National University
local.identifier.essn1471-2334
local.bibliographicCitation.issue1
local.bibliographicCitation.startpage12
local.identifier.doi10.1186/1471-2334-12-12
dc.date.updated2016-02-24T09:05:38Z
local.identifier.scopusID2-s2.0-84855998060
local.identifier.thomsonID000313767100014
CollectionsANU Research Publications

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