Epidemiology of Toxoplasma gondii infections in humans and selected wildlife and domestic animal species in an interface area in the Bushbuckridge Municipality, Mpumalanga, South Africa

Abstract

Toxoplasma gondii (T. gondii) is an obligate protozoan parasite in warm-blooded animals of global importance and affecting approximately 30-50 % of the human population (approximately more than two billion people) worldwide. This parasite is able to infect a wide range of mammals and birds including livestock, wildlife, domestic animals, and humans. Its dissemination within the different animal species is highly dependent on the interspecies interactions and the environment. In the agricultural sector T. gondii was seen to cause economical losses in goats and sheep due to the increase of abortions.

Toxoplasma gondii has a noticeable effect globally on food safety and environmental health, which are the main issues of concern to reducing and preventing its spread. In most African countries including South Africa (SA), however, information on the national seroprevalence of T. gondii is limited in people and animals and has not yet been fully investigated.

This study investigated the epidemiology and dynamics surrounding T. gondii in the Bushbuckridge Municipality (Mpumalanga, South Africa). Both serological (latex agglutination commercial kit) and molecular techniques (multiplex nested PCR detecting genetic markers SAG1, SAG2b, SAG3, PK1 and C22-8) were used to determine the prevalence in humans, livestock from informal farms, domestic animals and feral rodents (captured rodents). A questionnaire survey targeting the community members was also conducted to get a better understanding of the socio-economical, environmental and husbandry conditions in the area. The seroprevalence in humans, cats, chickens, goats and rodents was 8.8%, 0.0%, 4.2%, 11.2% and 18.0%, respectively. Seroprevalence in impalas, kudus, wild dogs, wildebeests, warthogs and zebras was estimated at 5.2%, 7.3%, 100.0%, 20.9%, 13.4% and 9.1%, respectively. The results reveal a low prevalence of T. gondii in the human, domestic cycle and most of the wildlife species. The highest seroprevalence was detected in wild dogs possibly indicating that the dominating route of transmission could be through the ingestion of contaminated meat in wildlife. Rodents captured in different habitats showed a relatively high seroprevalence of T. gondii in human dwellings (19.0%), croplands (15.3%) and nature conservation (20.2%) habitats, which suggests that rodents could be the possible bridges between the wildlife cycle and the surrounding human and domestic cycles in the interface area. The questionnaire revealed that 63.0% of the household owners are informal farmers and 35.9% are pet owners. A high female participation was found at 75.3% when compared to males at 24.7%, which also indicates that the women are possibly the ones that care and manage the livestock and pets in the households. Strains from lineages Type II and Type III were detected circulating in the studied area with variation detected in satellite markers SAG1 and SAG3, possibly suggesting an atypical T. gondii circulating in the area. This study is important and beneficial because it displays current epidemiological information relating to the distribution, the possible transmission and incidence of T. gondii in the Bushbuckridge Municipality (Mpumalanga, South Africa).