Concurrent cryptococcal and dengue meningoencephalitis as initial presentation of human immunodeficiency virus infection in a patient from arbovirus-endemic northeastern Brazil: a case report.

BACKGROUND: Co-infections involving dengue virus (DENV) and opportunistic fungal pathogens are rarely reported alongside human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS). To our knowledge, no prior cases of DENV and Cryptococcus neoformans coinfection have been documented. This case highlights a novel presentation of concurrent DENV and cryptococcal meningoencephalitis in an immunocompromised host, reinforcing the importance of considering multiple etiologies in patients from tropical regions presenting with neurological symptoms. CASE PRESENTATION: A 21-year-old Brazilian male with previously unknown HIV status presented with fever and signs of meningeal irritation, without neurological deficits. Initial laboratory evaluations revealed lymphopenia, thrombocytopenia, and elevated transaminase levels. DENV infection was confirmed by serological testing (NS1 antigen and IgM positivity) and by cerebrospinal fluid with DENV IgM reactivity, leading to a diagnosis of dengue meningoencephalitis. HIV serology subsequently tested positive. After the initiation of antiretroviral therapy, he developed worsening headaches followed by neurological deficits. A second lumbar puncture confirmed cryptococcal meningitis by India ink staining and multiplex PCR, with additional confirmation by fungal culture. The patient was diagnosed with concomitant dengue fever and cryptococcal meningoencephalitis. CONCLUSIONS: This is the first reported case of concurrent DENV and C. neoformans meningoencephalitis in a patient with HIV. The overlapping symptomatology of arboviral and opportunistic infections can complicate diagnosis, particularly in endemic areas with limited resources. This case underscores the importance of maintaining a broad differential diagnosis in patients presenting with systemic and neurological symptoms who are immunocompromised, especially in tropical regions where multiple pathogens may co-circulate. Awareness of unusual co-infections is essential to ensure timely diagnosis and appropriate management, ultimately improving patient outcomes. CLINICAL TRIAL NUMBER: Not applicable.