Young Adult with Fever, Headache After Returning From Puerto Rico

Why It Matters

Dengue’s spread to mainland U.S. poses diagnostic challenges for clinicians and underscores gaps in preventive options, especially after the withdrawal of the only FDA‑approved vaccine.

Key Takeaways

• Dengue endemic in Puerto Rico, now seen in US Gulf
• Fever, rash, thrombocytopenia, ascites indicate dengue warning signs
• Early NAAT confirms dengue; IgM used after day 7
• US dengue vaccine withdrawn, leaving no approved option
• Supportive care often resolves dengue without antivirals

Pulse Analysis

Dengue fever, caused by four distinct serotypes of the dengue virus, has long been endemic in the Caribbean and Latin America. Increased travel and climate‑driven expansion of Aedes mosquito habitats have pushed the disease into the continental United States, with sporadic autochthonous cases reported in Florida, Texas, Arizona and California. The case of a Texas‑based soldier who contracted dengue during a family visit to Puerto Rico illustrates how quickly the virus can cross borders, turning a routine vacation into a public‑health concern for military and civilian health systems alike.

The patient’s presentation—high fever, retro‑orbital headache, diffuse maculopapular rash with petechiae, thrombocytopenia, leukopenia and mild hepatic enlargement—matches the WHO’s dengue classification with warning signs such as fluid leakage (ascites) and rapid platelet drop. Dengue typically progresses through a febrile phase, a critical phase marked by vascular permeability, and a recovery phase where symptoms abate. Early diagnosis relies on nucleic acid amplification testing within the first week, while serologic IgM assays become reliable after day seven. Prompt recognition of these patterns enables clinicians to provide supportive care and avoid unnecessary antibiotics.

Therapeutic options for dengue remain limited to fluid management and symptom control, as no antiviral has received regulatory approval. The United States once relied on Sanofi’s Dengvaxia, a tetravalent live‑attenuated vaccine approved in 2019 for seropositive adolescents, but production ceased in 2024, leaving a void in preventive strategies. This gap heightens the importance of vector control, traveler education, and early clinical suspicion, especially for military personnel deployed to endemic regions. Strengthening surveillance and investing in next‑generation vaccines are critical to curb dengue’s expanding footprint on American soil.