High brucellosis prevalence and risk among children aged 5–14 years in Kenyan pastoral health facilities: A facility-based surveillance study
Abstract
Background Brucellosis remains endemic in pastoral sub-Saharan Africa, but facility-based data on human prevalence and associated factors in these communities are limited. We estimated brucellosis prevalence and associated factors among febrile patients at two pastoral health facilities in Kenya. Methodology/Principal findings We conducted prospective facility-based surveillance from February 2023 to July 2024 at Laisamis Sub-County Referral Hospital, Marsabit County, and Mailwa Health Center, Kajiado County. Patients aged ≥1 year with acute febrile illness and brucellosis-compatible symptoms were enrolled consecutively. Blood samples were tested using Rose Bengal Test serology, real-time PCR for Brucella DNA, and indirect ELISA. Cases were classified hierarchically as RBT titer ≥1:8, PCR positivity among low-titer RBT-reactive samples, or low-titer RBT reactivity with ELISA IgG positivity. Modified Poisson regression with robust variance estimated adjusted prevalence ratios (aPR). Of 443 enrolled participants, four lacked sufficient laboratory information, leaving 439 for analysis. Overall, 67 participants met the brucellosis case definition (15.3%; 95% CI: 12.2–18.9%). Prevalence was higher in Laisamis than Mailwa (19.4% vs. 3.5%; p < 0.001). Children aged 5–14 years had the highest age-specific prevalence (31.3%; 95% CI: 22.4–41.9%) and accounted for 38.8% of cases. In multivariable analysis, brucellosis was associated with age 5–14 years (aPR 2.35; 95% CI: 1.51–3.68), prolonged fever >7 days (aPR 1.83; 95% CI: 1.20–2.78), and muscle pain (aPR 2.29; 95% CI: 1.02–5.13). Under a restricted case definition, prevalence decreased to 11.6%, but core associations remained directionally consistent. Conclusions/Significance Brucellosis was common among febrile patients at two Kenyan pastoral health facilities, with highest prevalence among children aged 5–14 years and marked site heterogeneity. Findings support improved clinical recognition of brucellosis in pastoral facilities and further investigation of age-patterned household exposure pathways.