Abstract
Background
Between December 2015 and July 2016, a yellow fever (YF) outbreak affected urban areas
of Angola and the Democratic Republic of the Congo (DRC). We described the outbreak in
DRC and assessed the accuracy of the YF case definition, to facilitate early diagnosis of
cases in future urban outbreaks.
Methodology/Principal findings
In DRC, suspected YF infection was defined as jaundice within 2 weeks after acute fever
onset and was confirmed by either IgM serology or PCR for YF viral RNA. We used case
investigation and hospital admission forms. Comparing clinical signs between confirmed
and discarded suspected YF cases, we calculated the predictive values of each sign for confirmed YF and the diagnostic accuracy of several suspected YF case definitions. Fifty seven
of 78 (73%) confirmed cases had travelled from Angola: 88% (50/57) men; median age 31
years (IQR 25–37). 15 (19%) confirmed cases were infected locally in urban settings in
DRC. Median time from symptom onset to healthcare consultation was 7 days (IQR 6–9), to
appearance of jaundice 8 days (IQR 7–11), to sample collection 9 days (IQR 7–14), and to
hospitalization 17 days (IQR 11–26). A case definition including fever or jaundice, combined
with myalgia or a negative malaria test, yielded an improved sensitivity (100%) and specificity (57%).
Conclusions/Significance
As jaundice appeared late, the majority of cases were diagnosed too late for supportive care
and prompt vector control. In areas with known local YF transmission, a suspected case definition without jaundice as essential criterion could facilitate earlier YF diagnosis, care and control.