Prevalence of Toxoplasma gondii in commensal pest rodents at the National Zoological Garden in South Africa

Abstract

Toxoplasmosis is a zoonotic disease caused by the ubiquitous Apicomplexan protozoa Toxoplasma gondii (T. gondii). The overall epidemiology of T. gondii in Southern Africa is understudied. Although a few studies have documented its circulation in humans, domestic animals, and wild animals, these studies were limited in species diversity and geographical location. Rodents are intermediate hosts and are recognised as key reservoir hosts for T. gondii. Rodents play an important role in the maintenance and transmission of the parasite as they are preyed on by cats, the definitive hosts. Toxoplasma gondii infection rates in the local rodent population may reflect infection rates in cats. The aim of this study was to determine the prevalence of T. gondii in pest rodents within the South African National Biodiversity Institute National Zoological Garden (SANBI NZG). Furthermore, an attempt was made to confirm the presence of T. gondii DNA in the various rodents’ tissues (brain, tongue, muscle, diaphragm, and heart) using quantitative polymerase chain reaction (qPCR). A total of 138 sera were tested for T. gondii antibodies using a commercial latex agglutination test. A cut-off titre ≥ 64 was used to distinguish between positive and negative cases. Ten samples were positive for T. gondii antibodies, bringing the overall prevalence to 7.25% (95%, CI= 3.53 – 12.92). Using the generalised linear model, there was a statistically significant (p<0.00432) positive correlation between presence of T. gondii antibodies and rodent body weight. No T. gondii DNA amplification was observed on the tissue samples from the ten T. gondii antibody positive rodents. The results of this study provide baseline knowledge about the role of rodents in the epidemiology of T. gondii natural infections, particularly in the human-wildlife interface.