title: The early clinical features of dengue in adults: challenges for early clinical diagnosis.
abstract: BACKGROUND
  The emergence of dengue throughout the tropical world is affecting an increasing proportion of adult cases. The clinical features of dengue in different age groups have not been well examined, especially in the context of early clinical diagnosis.
  
  
  RESULTS
  We structured a prospective study of adults (≥ 18 years of age) presenting with acute febrile illness within 72 hours from illness onset upon informed consent. Patients were followed up over a 3-4 week period to determine the clinical outcome. A total of 2,129 adults were enrolled in the study, of which 250 (11.7%) had dengue. Differences in the rates of dengue-associated symptoms resulted in high sensitivities when the WHO 1997 or 2009 classification schemes for probable dengue fever were applied to the cohort. However, when the cases were stratified into age groups, fewer older adults reported symptoms such as myalgia, arthralgia, retro-orbital pain and mucosal bleeding, resulting in reduced sensitivity of the WHO classification schemes. On the other hand, the risks of severe dengue and hospitalization were not diminished in older adults, indicating that this group of patients can benefit from early diagnosis, especially when an antiviral drug becomes available. Our data also suggests that older adults who present with fever and leukopenia should be tested for dengue, even in the absence of other symptoms.
  
  
  CONCLUSIONS
  Early clinical diagnosis based on previously defined symptoms that are associated with dengue, even when used in the schematics of both the WHO 1997 and 2009 classifications, is difficult in older adults.
authors.affiliation: Communicable Diseases Centre, Tan Tock Seng Hospital, Singapore, Singapore.
authors.forename: Jenny G H
authors.initials: JG
authors.lastname: Low
authors.forename: Adrian
authors.initials: A
authors.lastname: Ong
authors.forename: Li Kiang
authors.initials: LK
authors.lastname: Tan
authors.forename: Shera
authors.initials: S
authors.lastname: Chaterji
authors.forename: Angelia
authors.initials: A
authors.lastname: Chow
authors.forename: Wen Yan
authors.initials: WY
authors.lastname: Lim
authors.forename: Koon Wui
authors.initials: KW
authors.lastname: Lee
authors.forename: Robert
authors.initials: R
authors.lastname: Chua
authors.forename: Choon Rong
authors.initials: CR
authors.lastname: Chua
authors.forename: Sharon W S
authors.initials: SW
authors.lastname: Tan
authors.forename: Yin Bun
authors.initials: YB
authors.lastname: Cheung
authors.forename: Martin L
authors.initials: ML
authors.lastname: Hibberd
authors.forename: Subhash G
authors.initials: SG
authors.lastname: Vasudevan
authors.forename: Lee-Ching
authors.initials: LC
authors.lastname: Ng
authors.forename: Yee Sin
authors.initials: YS
authors.lastname: Leo
authors.forename: Eng Eong
authors.initials: EE
authors.lastname: Ooi
mesh_terms: D000328:Adult; D003715:Dengue / Q000175:diagnosis* / Q000473:pathology*; D042241:Early Diagnosis; D005260:Female; D005335:Fever of Unknown Origin / Q000175:diagnosis; D005500:Follow-Up Studies; D006801:Humans; D007970:Leukopenia / Q000175:diagnosis; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012720:Severity of Illness Index