Molecular detection of Toxoplasma gondii in fresh water fish from major rivers in Nigeria: a preliminary survey

Abstract

Introduction: toxoplasmosis, caused by Toxoplasma gondii, is a recognised neglected tropical disease, and a major re-emerging One Health challenge globally. Its prevalence varies from moderate to high across different hosts and regions. The status of toxoplasmosis in fish in Nigeria is not yet sufficiently studied. This study assessed the occurrence of T. gondii in freshwater fish species captured from major rivers in Nigeria to provide data on their toxoplasmosis status and level of environmental contamination with the parasite´s oocysts. Methods: a total of 90 fish species were captured from the River Benue, the River Niger, and the confluence at Lokoja. Their gills and intestines were harvested, homogenised, and tested for T. gondii gene using nested polymerase chain reaction. Results: the DNA of T. gondii was not detected in the gills and intestines of any of the captured fish. This indicates an occurrence of 0% in the fish. Conclusion: this report is the first attempt at detecting the presence of T. gondii in freshwater fish from the River Niger, the River Benue, and their confluence at Lokoja. The results reported may imply that freshwater fish species from these rivers may be a low risk of toxoplasmosis transmission. However, further studies are needed, including other fish species and bivalves, and a larger sample size is recommended across all seasons.