Visceral leishmaniasis relapse: what do we know and what should we learn from Brazilian episodes reported from 2014 to 2020?

Abstract

There is a lack of knowledge regarding the eventual differences in the clinical and sociodemographic characteristics comparing VL relapse events with new onset VL events. We analyzed the clinical and epidemiological profile of new occurrence and relapse events in patients with VL in Brazil over the 2014-2020 period, using linked databases of VL and HIV/AIDS cases from the Notifiable Diseases Information System (SINAN), the Logistics Control System for Medications (SICLOM) and the Laboratory Test Control System (SISCEL) for HIV/AIDS. New VL case event was defined as VL reported in patients with no previous registry of VL during the past 12 months. Relapse event was defined as VL reported in patients with previous registry of VL during the past 12 months after the cure. Between 2014 and 2024, 23,025 VL events were reported, 93.75% were recorded as new case events and 6.25% as relapse events. When comparing the new case to relapse events, we observed that, respectively: 66% and 70% of patients were male, (p = 0.003); 43% and 34% were under 15 years of age (p < 0.001); and 41% and 43% had education up to high school (p < 0.001). Symptoms such as fever, weakness, weight loss, pallor, and jaundice were more frequent in new case than in relapse events (p < 0.05). Relapses were proportionally more frequent in patients co-infected with VL/HIV (41%) compared to new cases (11%) (p<0.001). Among HIV coinfected patients, CD4⁺/CD8⁺ T lymphocyte count and median HIV viral load were significantly lower in relapse events. To better understand such differences in new and relapse cases, in depth prospective studies to identify factors associated with relapse in VL patients are essential.