Misdiagnosis of oropouche virus in cancer patients: mimicry of treatment-related complications.

Misdiagnosis of oropouche virus (OROV) infection in cancer patients is an emerging clinical concern, particularly in regions reporting more than 500 000 cumulative OROV infections. The virus typically presents with fever in nearly 100% of cases, headache in up to 80%, myalgia in 60%, and leukopenia in approximately 40%, creating substantial overlap with chemotherapy-induced myelosuppression, immunotherapy-related toxicities, and radiotherapy-associated inflammatory syndromes. This clinical mimicry often leads to inappropriate antibiotic use, unwarranted hospitalization, and delays or dose modifications in cancer treatment. As OROV transmission expands through vector proliferation and increased human mobility, accurate recognition becomes essential. Incorporating RT-PCR testing into diagnostic pathways for febrile oncology patients in endemic areas can prevent misclassification and preserve continuity of cancer care.