Dengue Fever in Patients with Hematological Malignancies and Hematopoietic Stem Cell Transplantation Recipients: Clinical Characteristics and Outcomes.

Dengue is a hyperendemic arboviral infection with a broad clinical spectrum, ranging from self-limited illness to severe disease with shock and multiorgan dysfunction. Immunosuppressed individuals, particularly patients with hematological malignancies (HM) and those who have undergone hematopoietic cell transplantation (HCT), may be at increased risk for severe manifestations. However, data regarding dengue infection in this population remain limited, especially in endemic settings. Methods: We conducted a retrospective, single-center observational study including adult patients with HM who were diagnosed with laboratory-confirmed dengue virus infection between February and July 2024. Patients were stratified according to prior HCT status (HCT versus non-HCT). Dengue severity was classified according to Brazilian Ministry of Health criteria. Clinical characteristics, laboratory findings, outcomes, and 30-day overall survival were analyzed. Logistic regression models were used to identify factors associated with dengue warning signs. Results: A total of 53 patients were included, of whom 17 (32%) had previously undergone HCT (71% autologous and 29% allogeneic). Age and sex distribution were similar between groups, while underlying hematological diagnoses differed, with multiple myeloma predominating in the HCT group and lymphoma in the non-HCT group (P = .04). Dengue warning signs were significantly more frequent among HCT recipients (71% versus 22%, P < .001), as was grade C dengue (65% versus 19%, P < .001). Hypotension requiring vasopressor support occurred exclusively in the HCT group (18% versus 0%, P = .03). Severe thrombocytopenia at diagnosis (platelet count <20,000/μL) was more common in HCT patients (47% versus 17%, P = .02). In multivariate analysis, male sex (OR 71.11, 95% CI 2.72 to 1856.76), prior HCT (OR 40.60, 95% CI 2.13 to 775.62), and platelet count <20,000/μL (OR 17.15, 95% CI 1.47 to 199.53) were independently associated with dengue warning signs. Thirty-day overall survival was lower in the HCT group (88% versus 100%, P < .02). Dengue infection in patients with HM, particularly those with prior HCT, is associated with increased disease severity, higher rates of warning signs, and worse short-term outcomes. Heightened clinical suspicion, early diagnostic testing, and close monitoring are essential to improve outcomes in this high-risk population in dengue-endemic regions.