Epidemiology of human and animal leptospirosis in Kenya: A systematic review and meta-analysis of disease occurrence, serogroup diversity and risk factors

Background Leptospirosis is a priority zoonotic disease in Kenya, but an in-depth review of its presence in humans, animals and the environment is lacking. Therefore, we conducted this systematic review and meta-analysis to understand the epidemiological situation to date.Methodology We searched for literature in African journals online, AGRIS, Embase, the Leptospira WOAH reference laboratory library, ProMED-mail, PubMed, Scopus, Web of Science, and the institutional repositories of 33 academic institutions and included 66 publications on leptospirosis in Kenya which spanned from 1951 to 2022. The review was registered on the International Platform of Registered Systematic Review and Meta-analysis Protocols (INPLASY).Findings Most investigations were done in rural and urban areas in western, southern, central, and coastal areas in Kenya and the largely pastoral eastern and northern areas were under-represented. A wide host range of domestic animals and wildlife was revealed, and occupational exposure was an important risk factor for humans. The microscopic agglutination test (MAT) was the most frequent test, particularly common in studies conducted during the 1980s and 1990s. However, varying MAT panels and cut-off titres were observed. The overall seroprevalence in cattle was 28.2% (95% confidence intervals [CI]: 12.0-53.0; heterogeneity: I2 = 96.7%, tau 2 = 1.4), and 11.0% in goats (95% CI: 5.4-21.2; heterogeneity: I2 = 78.8%, tau 2 = 0.4). Molecular tests were seldom used to determine species and illustrate strain diversity. There was a lack of awareness of leptospirosis among farmers and health practitioners.Conclusion The widespread presence of leptospires and inadequate diagnostic capacity demonstrate that leptospirosis is a common but underreported disease in Kenya. Raising awareness and boosting the country's diagnostic capacity is crucial to timely detection and disease control. Leptospirosis is a prevalent but understudied zoonotic disease in Kenya. A comprehensive review of the presence of the disease in various hosts is therefore needed to catalogue the research efforts and inspire future scientific inquiry on this neglected tropical disease. We therefore undertook this comprehensive review of published literature in leading databases and institutional repositories of relevant Kenyan higher institutions of learning. Literature spanning more than 70 years was identified and study areas showed a regional bias towards central, western, southern and coastal regions. The arid and semi-arid areas in the northern and eastern regions with large animal and wildlife populations that could facilitate leptospiral transmission were under-represented, and the inclusion of these pastoral regions could give a better picture of the country's leptospirosis risk profile. Summary estimates in cattle and goats revealed considerable pooled seroprevalence of leptospirosis and the need for control in animal hosts. A low awareness among farmers, and animal and public health practitioners was found, demonstrating the need for education initiatives that can facilitate at-risk populations such as farmers. Additionally, the country lacks the capacity for MAT testing, and recent efforts to culture for leptospires are non-existent. Understanding the circulating serovars and strain diversity is crucial to the effective control of leptospirosis. Investments in diagnostics for peripheral and central laboratories are vital for public health response.