Prevalence of Human and Animal African Trypanosomiasis in Nigeria: a Scoping Review

Abstract

Background African trypanosomiasis affects both humans (HAT) and animals (AAT). HAT is an NTD targeted for elimination in 2030, and has not been officially reported by WHO from Nigeria in the last decade despite frequent reports of animal carriers. Conversely, the burden of AAT continues to increase. This study synthesized published evidence on the prevalence of African trypanosomiasis within human and animal populations in Nigeria, the trypanosome species involved, the spread of animal reservoirs, and the variability in diagnostic methodologies employed. Methodology/principal findings A scoping review was performed following the methodological framework outlined in PRISMA-ScR checklist. A total of 16 eligible studies published between 1993 and 2021 were reviewed. 13 studies reported the prevalence of AAT, and 3 for HAT. Varying prevalence rates were recorded depending on the diagnostic methods employed. The overall prevalence of HAT was 3.6%, and AAT 27.3%. The highest incidence of HAT was detected using the Card Agglutination Test for Trypanosomiasis (CATT), and AAT by PCR, followed by microscopy (the most used technique). Domestic animals like cattle, pigs, and dogs were identified as carriers of the human-infective trypanosomes (T. brucei gambiense). Conclusion This study highlights the high prevalence and complex epidemiology of African trypanosomiasis in humans and animals in Nigeria. Remarkably, published evidence indicate that HAT is highly prevalent in Nigeria despite not being reported by WHO. However, only few studies have investigated HAT in Nigeria, indicating limited disease surveillance. Unfortunately, diagnostics challenges and disease reporting protocols seem to limit HAT reporting to WHO. Therefore, adequately coordinated epidemiological surveys and targeted intervention policies are imperative to ascertain the true epidemiological status of HAT in Nigeria towards achieving WHO’s elimination targets in 2030. The presence of animal carriers of human-infective trypanosomes underscores the importance of a one-health approach to avoid breeding the next epidemic clone in Nigeria and combat African trypanosomiasis effectively.