Hospital-Based Seroprevalence and Socio-Environmental Predictors of Human Leishmaniasis in Baringo County, Kenya: Implications for One Health Surveillance and Control

Background: Leishmaniasis is a vector-borne neglected tropical disease caused by obligate intracellular protozoan parasites of the genus Leishmania and transmitted by bites from infected female phlebotomine sand flies. Visceral leishmaniasis (VL), the most severe clinical form, remains a major public health concern in Eastern Africa and a priority for control and elimination. Although Baringo County is a well-established endemic focus in Kenya, the spatial distribution of human exposure and the socio-environmental determinants of infection remain inadequately characterized. This hospital-based cross-sectional study therefore estimated Leishmania seroprevalence. It assessed the sociodemographic, behavioral, and environmental predictors of seropositivity among patients presenting with clinical features suggestive of VL in two endemic sub-counties of Baringo County. Methods: A hospital-based cross-sectional study was conducted from January to March 2026 at Marigat and Chemolingot Sub-County Hospitals. We enrolled 260 patients with clinical features suggestive of VL through systematic sampling and tested them using the rK39 rapid diagnostic test (RDT) and an indirect enzyme-linked immunosorbent assay (ELISA). We collected sociodemographic, behavioral, household, and environmental data using a structured questionnaire. Associations between explanatory variables and ELISA seropositivity were evaluated using Pearson’s chi-square test or Fisher’s exact test. We included variables with p < 0.25 in multivariable logistic regression to identify independent predictors of seropositivity. Agreement between the rK39 RDT and ELISA was assessed using Cohen’s kappa statistics. We confirmed classical positive cases using bone marrow aspirates. Results: Overall Leishmania seroprevalence was 18.5% (95% CI: 14.2–23.7) by rK39 RDT and 20.8% (95% CI: 16.2–26.2) by ELISA. ELISA seroprevalence was substantially higher in Tiaty Sub-County (36.6%) than in Baringo South Sub-County (4.7%). Residence in Tiaty was independently associated with markedly higher odds of seropositivity than residence in Baringo South [aOR] = 11.30, 95% CI: 1.96–64.97; p = 0.007. Compared with children aged < 15 years, participants aged 15–44 years had lower odds of seropositivity (aOR = 0.30, 95% CI: 0.11–0.93; p = 0.037). Residents without a dog had higher odds of seropositivity (aOR = 3.17, 95% CI: 1.06–9.50; p = 0.039) than those with a dog. After adjustment, no other predicted factors were independently associated with seropositivity, suggesting that geographical differences may have confounded the unadjusted associations. Conclusion: Leishmania seroprevalence was substantial and unevenly distributed, with Tiaty Sub-County and children under 15 years bearing the greatest burden. Therefore, targeted, child-focused surveillance and integrated One Health interventions, including early case detection, improved housing, personal protection, vector-habitat management, and community education, are needed to strengthen VL control and advance the WHO 2030 targets for the Neglected Tropical Diseases Roadmap 2021–2030.