Yellow Fever and Dengue

Abstract

Dengue and yellow fever are common arboviral infections in humans [Call Out Box 35.1]. The two infections overlap substantially with regard to their epidemiology, pathogenesis, and clinical features. Both infections remain high on the differential diagnosis for any acutely ill patient who has traveled to or who lives in an endemic area. Understanding the epidemiology, pathogenesis, and clinical manifestations, together with maintaining a high index of suspicion for these infections in the appropriate context, allows for a prompt diagnosis and development of a treatment plan. Patients with yellow fever or dengue typically have active viral replication if they are febrile, allowing for diagnostic confirmation using polymerase chain reaction-based assays, antigen detection assays, or viral culture. Once the period of viremia has passed, diagnosis is supported (usually retrospectively) using serologic assays designed to detect pathogen-specific immunoglobulin (Ig) M, IgG, or neutralizing antibodies. There are no licensed antiviral medications for the treatment of either yellow fever or dengue; the mainstay of therapy is supportive care. The yellow fever 17D vaccine is one of the most successful vaccines of all time and remains widely used in endemic areas of the world. It is also an important travel vaccine. Some countries require proof of vaccination before allowing visitors to enter. A dengue vaccine was recently licensed for use, but its performance profile is inferior to the yellow fever vaccine. With proper recognition and treatment, the prognosis for patients with dengue is very good, while the prognosis for patients infected with yellow fever virus remains guarded.