A Case of Visceral Leishmaniasis in an Immunocompetent Adult.

Visceral leishmaniasis is a rare parasitic infection in immunocompetent individuals, being more frequent in children and immunocompromised individuals. Despite being endemic in several regions of the world, including Portugal, it continues to be underdiagnosed. The most characteristic clinical manifestations include constitutional symptoms, pancytopenia, polyclonal hypergammaglobulinemia, and splenomegaly. Direct identification of the parasite is the preferred diagnostic method; however, this approach is not always feasible. Consequently, serological testing becomes essential, particularly in immunocompetent individuals when supported by a compatible clinical, laboratory, and epidemiological context. We present the case of a 72-year-old woman residing in a rural area of Portugal who developed an insidious course of constitutional symptoms accompanied by pancytopenia, polyclonal hypergammaglobulinemia, elevated erythrocyte sedimentation rate, and splenomegaly. After an extensive diagnostic evaluation and exclusion of multiple infectious, hematologic, autoimmune, and neoplastic disorders, serological testing for leishmaniasis returned positive results, despite the inability to directly visualize the parasite in the bone marrow aspirate. Liposomal amphotericin B was initiated; however, the patient developed urinary septic shock and died. This case highlights the importance of considering VL in immunocompetent adults with a suggestive clinical, laboratory, and epidemiological context. It also emphasizes the diagnostic complexity of the disease and the value of serological methods in establishing the diagnosis, enabling early recognition and helping to avoid delays in management.