title: Clinical and epidemiological features of typhoid fever in Pemba, Zanzibar: assessment of the performance of the WHO case definitions.
abstract: BACKGROUND
  The gold standard for diagnosis of typhoid fever is blood culture (BC). Because blood culture is often not available in impoverished settings it would be helpful to have alternative diagnostic approaches. We therefore investigated the usefulness of clinical signs, WHO case definition and Widal test for the diagnosis of typhoid fever.
  
  
  RESULTS
  Participants with a body temperature ≥37.5°C or a history of fever were enrolled over 17 to 22 months in three hospitals on Pemba Island, Tanzania. Clinical signs and symptoms of participants upon presentation as well as blood and serum for BC and Widal testing were collected. Clinical signs and symptoms of typhoid fever cases were compared to other cases of invasive bacterial diseases and BC negative participants. The relationship of typhoid fever cases with rainfall, temperature, and religious festivals was explored. The performance of the WHO case definitions for suspected and probable typhoid fever and a local cut off titre for the Widal test was assessed. 79 of 2209 participants had invasive bacterial disease. 46 isolates were identified as typhoid fever. Apart from a longer duration of fever prior to admission clinical signs and symptoms were not significantly different among patients with typhoid fever than from other febrile patients. We did not detect any significant seasonal patterns nor correlation with rainfall or festivals. The sensitivity and specificity of the WHO case definition for suspected and probable typhoid fever were 82.6% and 41.3% and 36.3 and 99.7% respectively. Sensitivity and specificity of the Widal test was 47.8% and 99.4 both forfor O-agglutinin and H- agglutinin at a cut-off titre of 1:80.
  
  
  CONCLUSIONS
  Typhoid fever prevalence rates on Pemba are high and its clinical signs and symptoms are non-specific. The sensitivity of the Widal test is low and the WHO case definition performed better than the Widal test.
authors.affiliation: International Vaccine Institute, Seoul, Korea. kthriemer@itg.be
authors.forename: Kamala
authors.initials: K
authors.lastname: Thriemer
authors.forename: Benedikt
authors.initials: B
authors.lastname: Ley
authors.forename: Benedikt B
authors.initials: BB
authors.lastname: Ley
authors.forename: Shaali S
authors.initials: SS
authors.lastname: Ame
authors.forename: Jaqueline L
authors.initials: JL
authors.lastname: Deen
authors.forename: Gi Deok
authors.initials: GD
authors.lastname: Pak
authors.forename: Na Yoon
authors.initials: NY
authors.lastname: Chang
authors.forename: Ramadhan
authors.initials: R
authors.lastname: Hashim
authors.forename: Wolfgang Hellmut
authors.initials: WH
authors.lastname: Schmied
authors.forename: Clara Jana-Lui
authors.initials: CJ
authors.lastname: Busch
authors.forename: Shanette
authors.initials: S
authors.lastname: Nixon
authors.forename: Anne
authors.initials: A
authors.lastname: Morrissey
authors.forename: Mahesh K
authors.initials: MK
authors.lastname: Puri
authors.forename: R Leon
authors.initials: RL
authors.lastname: Ochiai
authors.forename: Thomas
authors.initials: T
authors.lastname: Wierzba
authors.forename: John D
authors.initials: JD
authors.lastname: Clemens
authors.forename: Mohammad
authors.initials: M
authors.lastname: Ali
authors.forename: Mohammad S
authors.initials: MS
authors.lastname: Jiddawi
authors.forename: Lorenz
authors.initials: L
authors.lastname: von Seidlein
authors.forename: Said M
authors.initials: SM
authors.lastname: Ali
mesh_terms: D000293:Adolescent; D000328:Adult; D000372:Agglutination Tests; D002648:Child; D002675:Child, Preschool; D005260:Female; D006761:Hospitals; D006801:Humans; D007195:Indian Ocean Islands / Q000453:epidemiology; D007223:Infant; D008297:Male; D008875:Middle Aged; D011336:Probability; D012485:Salmonella typhi / Q000302:isolation & purification*; D012680:Sensitivity and Specificity; D013636:Tanzania / Q000453:epidemiology; D014435:Typhoid Fever / Q000175:diagnosis* / Q000453:epidemiology*; D014944:World Health Organization; D055815:Young Adult