Complicated dengue rare in travelers, but doctors should be aware of the warning signs

A retrospective analysis of almost 6,000 persons with dengue found that while only 2 percent of cases were considered complicated, almost all complicated cases had warning signs. The authors advise that clinicians should monitor patients with dengue closely for warning signs that may indicate progression to severe disease. The analysis is published in Annals of Internal Medicine.

Dengue is the leading cause of acute undifferentiated febrile illness among travelers returning to Europe from all continents except Africa. Severe dengue can lead to bleeding, shock, or organ failure. The 2009 World Health Organization (WHO) dengue classification distinguishes dengue with warning signs and severe dengue.

Warning signs in a patient with dengue include abdominal pain, persistent vomiting, fluid accumulation, mucosal bleeding, lethargy, liver enlargement, and increasing hematocrit with decreasing platelets. Recognition of these warning signs may facilitate timely triage of patients at risk for severe dengue.

Researchers from GeoSentinel, the emerging infectious diseases surveillance and research network of the U.S. Centers for Disease Control and Prevention (CDC) and the International Society of Travel Medicine (ISTM), conducted a retrospective chart review and analysis of 5,958 patients with dengue reported to the Network from January 2007 through July 2022, to describe the epidemiology, clinical characteristics, and outcomes among international travelers with severe dengue or dengue with warning signs as defined by the 2009 World Health Organization classification.

The researchers found that only 2 percent of cases were reported as complicated dengue. However, 99 percent of the patients with complicated dengue that completed a supplemental questionnaire had warning signs, and 31 percent were classified as severe. According to the authors, clinicians should monitor travelers with dengue closely for laboratory findings and signs that may indicate progression to severe disease, even if the predictive value of warning signs in travelers has not been fully validated.