title: Outbreak of 2009 pandemic influenza A(H1N1), Los Lagos, Chile, April-June 2009.
abstract: On 17 May 2009, the first two cases of 2009 pandemic influenza A(H1N1) were confirmed in the Metropolitan region (Santiago, Chile). On 6 June 2009, Chile reported 500 confirmed cases, seven severe and two fatal. Because six of the severe cases and the two deaths occurred in the region of Los Lagos in southern Chile, a retrospective study was conducted using data on emergency room visits as well as laboratory viral surveillance, during the period from 1 April to 31 May, in order to establish the date of the beginning of the outbreak. From 1 to 27 June, data were collected in real time, to establish the real magnitude of the outbreak, describe its transmission, clinical severity and secondary attack rates. Confirmed cases, their household contacts and healthcare workers were interviewed. This analysis showed that the outbreak in Los Lagos started on 28 April. By 27 June, a total of 14.559 clinical cases were identified, affecting mostly 5-19 year-olds. The effective reproduction number during the initial phase (20 days) was 1.8 (1.6-2.0). Of the 190 confirmed cases with severe acute respiratory infection, 71 (37.4%) presented a risk condition or underlying illness.
authors.affiliation: The Ministry of Health Task Force is integrated by experts of the Ministry of Heath (Epidemiology, Health care services, Clinicians, Laboratory), Scientific and Medical Society Experts, Santiago, Chile.
authors.forename: E
authors.initials: E
authors.lastname: Pedroni
authors.forename: M
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authors.lastname: Garcia
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authors.lastname: Espinola
authors.forename: A
authors.initials: A
authors.lastname: Guerrero
authors.forename: C
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authors.lastname: Gonzalez
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authors.lastname: Olea
authors.forename: M
authors.initials: M
authors.lastname: Calvo
authors.forename: B
authors.initials: B
authors.lastname: Martorell
authors.forename: M
authors.initials: M
authors.lastname: Winkler
authors.forename: Mv
authors.initials: M
authors.lastname: Carrasco
authors.forename: Ja
authors.initials: J
authors.lastname: Vergara
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authors.lastname: Ulloa
authors.forename: Am
authors.initials: A
authors.lastname: Carrazana
authors.forename: O
authors.initials: O
authors.lastname: Mujica
authors.forename: Je
authors.initials: J
authors.lastname: Villarroel
authors.forename: M
authors.initials: M
authors.lastname: Labrana
authors.forename: M
authors.initials: M
authors.lastname: Vargas
authors.forename: P
authors.initials: P
authors.lastname: Gonzalez
authors.forename: L
authors.initials: L
authors.lastname: Caceres
authors.forename: Cg
authors.initials: C
authors.lastname: Zamorano
authors.forename: R
authors.initials: R
authors.lastname: Momberg
authors.forename: G
authors.initials: G
authors.lastname: Munoz
authors.forename: J
authors.initials: J
authors.lastname: Rocco
authors.forename: V
authors.initials: V
authors.lastname: Bosque
authors.forename: A
authors.initials: A
authors.lastname: Gallardo
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authors.lastname: Elgueta
authors.forename: J
authors.initials: J
authors.lastname: Vega
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D002677:Chile / Q000453:epidemiology; D004196:Disease Outbreaks; D004636:Emergency Service, Hospital / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D007223:Infant; D053118:Influenza A Virus, H1N1 Subtype; D007251:Influenza, Human / Q000453:epidemiology* / Q000635:transmission; D008297:Male; D008875:Middle Aged; D011159:Population Surveillance; D012189:Retrospective Studies; D012307:Risk Factors; D055815:Young Adult