Seroprevalence and risk factors for brucellosis in cattle and rodents in Kilosa district, Morogoro, Tanzania

Background: Brucellosis is a global zoonosis caused by gram-negative bacteria that affects a diverse array of hosts including humans, domestic animals as well as wild animals such as cattle (B. abortus), goats, and sheep (B. melitensis), pigs (B. suis), and rodents (B. neotomae), and results in financial setbacks in the livestock industry. This study aimed to identify risk factors and estimate the seroprevalence of brucellosis in cattle and rodents in Kilosa district, Tanzania. Methods: A cross-sectional study was conducted from January 2023 to March 2023, cattle were randomly selected and rodents were trapped using Sherman, wire cages, and havahart traps. Blood samples were collected from the jugular vein and heart of the cattle and rodents, respectively. Sera were harvested from the collected blood and stored at – 20 ºC. All the sera were screened for brucella antibodies using the Rose Bengal Plate Test (RBPT) and confirmed by competitive Enzyme Linked Immuno Sorbent Assay (c-ELISA). The risk factors were captured using a structured questionnaire and analyzed by computing the Chi-square test and generalized linear model. Results: The seroprevalence of brucellosis was found to be 5.31% in cattle (95% CI: 0.0286-0.089) and 0.72% in rodents (95% CI: 0.0002-0.0397). A significant association was observed between grazing style and brucellosis seropositivity in cattle, with cattle that grazed together with sheep and goats having significantly higher odds of seropositivity (OR=6.5; 95% CI: 1.74-42.17, **p < 0.01). Conclusion: The detection of Brucella antibodies in both species indicates ongoing transmission and potential risk to public health. Our findings suggest that rodents may serve as reservoirs of brucellosis, contributing to its persistence and spread. Further research is essential to characterize the specific brucella species circulating among cattle and rodents and to understand the dynamics of interspecies transmission.