Prevalence of Leptospira antibodies in cattle, sheep, and goats in Kilwa District, Tanzania: a risk to public health

Background: Leptospirosis is a global zoonotic infection affecting both humans and animals in tropical and subtropical countries, including Tanzania. The objective of this study was to determine the prevalence of leptospirosis in livestock in Kilwa Southern Tanzania. Methods: A cross-sectional investigation was undertaken from January to March 2023 to establish the prevalence of leptospirosis in livestock in Kilwa district, southern Tanzania. A total of 100 blood samples from cattle, 120 blood samples from goats, and 20 blood samples from sheep were sampled from different selected sites for serum harvesting. Through a microscopic agglutination test, the collected serum samples were tested against five live leptospiral antigens to detect leptospiral antibodies. Common five reported serovars in Tanzania were used in this study such as leptospiral serovars Sokoine, Pomona, Grippotyphosa, Hebdomadis, and Lora. Results: The overall prevalence of leptospirosis in cattle was 26.0%=95%CI=0.1774-0.3573, in goats was 27.5%=95%CI=0.1975-0.3640, and in sheep was 30.0%=95%CI=0.1189-0.5428. Both livestock hosts demonstrated high prevalence with serovar Sokoine being the most prevalent serovar over others. Most of the antibody titers obtained suggested prolonged exposures of this livestock to leptospirosis infection and only a few antibody titers especially from goats suggest recent infection of leptospirosis Logistic regression analysis was performed to determine the association between different characteristics and disease. A significant (P=0.0086) association was obtained between disease prevalence and different characteristics such as location, sex, host, and serovars. Conclusion: Increased human-livestock contact raises the risk of disease transmission to both humans and animals. Reducing this disease burden, especially in low-income countries like Tanzania where livestock are key to income and food security, is essential. Vaccinating livestock with locally adapted strains can significantly reduce leptospirosis transmission.