Dengue: A reemerging concern for travelers
ABSTRACTDengue, a neglected tropical disease that is reemerging around the world, became a nationally notifiable disease in the United States in 2009. Travel to tropical and subtropical areas in the developing world poses the greatest risk of infection for US residents, and an increase in travel to these areas makes this infection more likely to be seen by primary care physicians in their practices.
KEY POINTS
- Dengue results from infection with one of four distinct serotypes: DENV-1, DENV-2, DENV-3, and DENV-4.
- The most common outcome after infection by the bite of an Aedes mosquito (which bites in the daytime) is asymptomatic infection, a flulike illness, or classic self-limited dengue fever. Severe, life-threatening disease with hemorrhagic manifestations or shock is rare.
- Obtaining a history of recent travel to a dengue-endemic area is a key in evaluating a person presenting with undifferentiated fever or a fever-rash-arthralgia syndrome.
- Diagnostic testing is based on the natural history of infection; antibody levels begin to rise as levels of viremia begin to decline.
- Risk factors help predict who will develop severe dengue after primary or secondary infection.
DIFFERENTIAL DIAGNOSES: INFECTIOUS AND NONINFECTIOUS
The differential diagnosis of uncomplicated dengue in a traveler returning from an endemic area includes viral, bacterial, and protozoal infections as well as noninfectious conditions (Table 1).53
Although most dengue virus infections are self-limiting, the clinical presentation may be severe enough to warrant hospitalization so that potentially life-threatening conditions can be systematically dismissed from the differential diagnosis.
Infections that can be rapidly fatal, such as malaria and enteric fever, need to be considered in patients who have traveled to endemic areas who present with undifferentiated fever. In cases of fever and maculopapular eruption, the differential diagnosis should include other causes of rash illness, such as measles and rubella. If hemorrhagic features are present, potentially fatal conditions need to be considered, including the classic viral hemorrhagic fevers caused by the Ebola and Marburg viruses, meningococcemia, the icterohemorrhagic form of leptospirosis, or other causes of bacterial sepsis. Other nonfatal infections should also be considered.
TREATMENT IS SUPPORTIVE
There is no antiviral treatment for dengue across the spectrum of disease presentations. Treatment is supportive and based on clinical presentation.
Acetaminophen (Tylenol) can be used to control fever, but aspirin and nonsteroidal anti-inflammatory drugs should not be used because they can make bleeding worse. Corticosteroids do not improve the outcome in severe dengue.2
Scrupulous attention to fluid and electrolyte balance is critical in severe dengue cases. Proper support and fluid resuscitation, including blood transfusion if needed, result in rapid recovery from dengue hemorrhagic fever with or without shock.
Suspected, probable, or confirmed cases of dengue should be reported to the local health department on the basis of published criteria (Table 3).
ADVICE TO TRAVELERS: DON’T GET BITTEN
There is currently no commercially available dengue vaccine, although several are under development.54 Therefore, pretravel counseling on how to avoid mosquito bites when traveling to dengue-endemic areas is the key dengue prevention strategy. Proactive prevention strategies include use of insect repellents such as those containing diethyltoluamide (DEET) or permethrin55 and elimination of outdoor locations where mosquitoes lay eggs, such as flower planter dishes, to reduce local mosquito breeding.56
Patients who have had a previous dengue infection should be counseled about the possible increased risk of severe disease if infected with a second dengue serotype.
Acknowledgment: The author thanks Chester G. Moore, PhD, of Colorado State University for assistance in creating Figure 2, based on data contained in the CDC, ArboNET, and Exotic/Invasive databases.
