title: Clinical and epidemiological features of Turkish children with 2009 pandemic influenza A (H1N1) infection: experience from multiple tertiary paediatric centres in Turkey.
abstract: BACKGROUND
  In April 2009 a novel strain of human influenza A, identified as H1N1 virus, rapidly spread worldwide, and in early June 2009 the World Health Organization raised the pandemic alert level to phase 6. Herein we present the largest series of children who were hospitalized due to pandemic H1N1 infection in Turkey.
  
  
  METHODS
  We conducted a retrospective multicentre analysis of case records involving children hospitalized with influenza-like illness, in whom 2009 H1N1 influenza was diagnosed by reverse-transcriptase polymerase chain reaction assay, at 17 different tertiary hospitals.
  
  
  RESULTS
  A total of 821 children with 2009 pandemic H1N1 were hospitalized. The majority of admitted children (56.9%) were younger than 5 y of age. Three hundred and seventy-six children (45.8%) had 1 or more pre-existing conditions. Respiratory complications including wheezing, pneumonia, pneumothorax, pneumomediastinum, and hypoxemia were seen in 272 (33.2%) children. Ninety of the patients (11.0%) were admitted or transferred to the paediatric intensive care units (PICU) and 52 (6.3%) received mechanical ventilation. Thirty-five children (4.3%) died. The mortality rate did not differ between age groups. Of the patients who died, 25.7% were healthy before the H1N1 virus infection. However, the death rate was significantly higher in patients with malignancy, chronic neurological disease, immunosuppressive therapy, at least 1 pre-existing condition, and respiratory complications. The most common causes of mortality were pneumonia and sepsis.
  
  
  CONCLUSIONS
  In Turkey, 2009 H1N1 infection caused high mortality and PICU admission due to severe respiratory illness and complications, especially in children with an underlying condition.
authors.affiliation: Department of Pediatrics, Ankara University Medical School ,  Ankara ,  Turkey.
authors.forename: Ergin
authors.initials: E
authors.lastname: Çiftçi
authors.forename: Nilden
authors.initials: N
authors.lastname: Tuygun
authors.forename: Halil
authors.initials: H
authors.lastname: Özdemir
authors.forename: Hasan
authors.initials: H
authors.lastname: Tezer
authors.forename: Gülnar
authors.initials: G
authors.lastname: Şensoy
authors.forename: İlker
authors.initials: İ
authors.lastname: Devrim
authors.forename: Nazan
authors.initials: N
authors.lastname: Dalgiç
authors.forename: Ateş
authors.initials: A
authors.lastname: Kara
authors.forename: Mehmet
authors.initials: M
authors.lastname: Turgut
authors.forename: Anil
authors.initials: A
authors.lastname: Tapisiz
authors.forename: Melike
authors.initials: M
authors.lastname: Keser
authors.forename: Solmaz
authors.initials: S
authors.lastname: Çelebi
authors.forename: Nuri
authors.initials: N
authors.lastname: Bayram
authors.forename: Emine
authors.initials: E
authors.lastname: Kocabaş
authors.forename: Ener Çağri
authors.initials: EÇ
authors.lastname: Dinleyici
authors.forename: Metehan
authors.initials: M
authors.lastname: Özen
authors.forename: Ahmet
authors.initials: A
authors.lastname: Soysal
authors.forename: Necdet
authors.initials: N
authors.lastname: Kuyucu
authors.forename: Gönül
authors.initials: G
authors.lastname: Tanir
authors.forename: Elif
authors.initials: E
authors.lastname: Çelikel
authors.forename: Nurşen
authors.initials: N
authors.lastname: Belet
authors.forename: Gültaç
authors.initials: G
authors.lastname: Evren
authors.forename: Didem Büyüktaş
authors.initials: DB
authors.lastname: Aytaç
authors.forename: Ali Bülent
authors.initials: AB
authors.lastname: Cengiz
authors.forename: Perihan Yasemen
authors.initials: PY
authors.lastname: Canöz
authors.forename: Okşan
authors.initials: O
authors.lastname: Derinöz
authors.forename: Erdal
authors.initials: E
authors.lastname: İnce
authors.forename: Mustafa
authors.initials: M
authors.lastname: Hacimustafaoğlu
authors.forename: Murat
authors.initials: M
authors.lastname: Anil
authors.forename: Özlem
authors.initials: Ö
authors.lastname: Özgür
authors.forename: Canan
authors.initials: C
authors.lastname: Kuzdan
authors.forename: Eda
authors.initials: E
authors.lastname: Özaydin
authors.forename: Nazik
authors.initials: N
authors.lastname: Aşilioğlu
authors.forename: Ceyhun
authors.initials: C
authors.lastname: Dizdarer
authors.forename: Mehmet
authors.initials: M
authors.lastname: Ceyhan
authors.forename: Ibrahim Hakan
authors.initials: IH
authors.lastname: Bucak
authors.forename: Tanil
authors.initials: T
authors.lastname: Kendirli
authors.forename: Halil İbrahim
authors.initials: Hİ
authors.lastname: Yakut
authors.forename: Tunç
authors.initials: T
authors.lastname: Fişgin
authors.forename: Nurettin
authors.initials: N
authors.lastname: Ünal
authors.forename: Hakan
authors.initials: H
authors.lastname: Altindağ
authors.forename: Ayşe Ayzit
authors.initials: AA
authors.lastname: Kilinç
authors.forename: Seray Umut
authors.initials: SU
authors.lastname: Zöhre
authors.forename: Atilla Halil
authors.initials: AH
authors.lastname: Elhan
authors.forename: Ülker
authors.initials: Ü
authors.lastname: Doğru
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D005260:Female; D006760:Hospitalization / Q000706:statistics & numerical data; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D053118:Influenza A Virus, H1N1 Subtype / Q000302:isolation & purification* / Q000472:pathogenicity; D007251:Influenza, Human / Q000453:epidemiology* / Q000401:mortality / Q000473:pathology* / Q000821:virology; D008297:Male; D058873:Pandemics; D012189:Retrospective Studies; D014421:Turkey / Q000453:epidemiology