Diagnosis and Management of Dengue Fever in a Nonendemic Country: Lessons From an Acute Febrile Illness in Iran During the COVID-19 Outbreak.

Dengue fever is a tropical arboviral disease that presents with a broad spectrum of clinical manifestations and can occasionally emerge in nonendemic regions due to factors such as international travel. This case report details a 47-year-old Iranian man who had recently returned from Jakarta, Indonesia, presenting with fever, diarrhea, vomiting, and myalgia during the COVID-19 outbreak. Despite initial misdiagnoses, dengue fever was confirmed through polymerase chain reaction (PCR) testing. Moreover, the serological analysis using enzyme-linked immunosorbent assay (ELISA) further demonstrated the presence of both IgM and IgG antibodies against the dengue virus. Initially, the patient's symptoms overlapped with COVID-19 and gastrointestinal infections, complicating the diagnosis. The management included supportive care, precautions against bleeding, fluid therapy, and empirical antibiotics due to suspected coinfections. This case highlights the importance of considering travel history and the possibility of nonendemic diseases in the differential diagnosis of febrile illnesses of unknown origin (FUO), particularly during concurrent outbreaks. Comprehensive history-taking and rigorous diagnostic evaluation are essential in such cases.