Imported dengue fever in East London: a 6-year retrospective observational study

Dengue fever (DF) is a frequently imported arthropod-borne infection in the United Kingdom but its broad range of clinical presentations makes it potentially unrecognized by clinicians.

We conducted a 6-year retrospective case note review of laboratory confirmed DF patients in East London in the period from 1 January 2010 through 31 December 2015. Epidemiological, clinical and laboratory features of imported DF were described. Risk factors associated with viraemic DF presentations were assessed.

Forty-four patients (4 from primary care clinics and 40 from three acute hospitals) were confirmed to have DF through RNA and/or IgM detection. In total, 86.4% (38/44) had primary infection compared to 13.6% (6/44) with secondary infection. Viraemic DF presentations accounted for 59.1% (26/44) of cases. The median age was 34 years (IQR 25-43). Most patients were males (68.2%, 30/44) and of non-white ethnicity (81.8%, 36/44). South Asia was the most frequent travel destination (52.3%, 23/44) followed by Southeast Asia (20.5%, 9/44). July-September was the peak season of presentation (43.2%, 19/44). The median interval between arrival in the UK and laboratory testing was 7 days (IQR 4-13). Arriving from abroad ≤ 7 days before molecular testing (age-adjusted odds ratios [OR] 16.98, 95% CI 2.43-118.75, P  =   0.004) and travel to South or Southeast Asia regions (age-adjusted OR 4.41, 95% CI 1.07-18.21, P  =   0.040) were associated with detectable viraemia at presentation. Only one DF patient met the WHO severity criteria. HIV serostatus was determined in 61.4% (27/44) of cases.

Clinicians need to improve DF recognition as well as rates of HIV testing in tropical travellers. Region of travel and time since arrival from DF endemic settings may help clinicians optimize requests for molecular testing. Further research on the clinical and public health aspects of imported DF is needed.