A Systematic Meta-Analysis ofToxoplasma gondiiPrevalence in Food Animals in the United States

Abstract

Toxoplasma gondii is a widely distributed protozoan parasite. The Centers for Disease Control and Prevention reported that T. gondii is one of three pathogens (along with Salmonella and Listeria), that together account for >70% of all deaths due to foodborne illness in the United States. Food animals are reservoirs for T. gondii and act as one of the sources for parasite transmission to humans. Based on limited population-based data, the Food and Agriculture Organization/World Health Organization estimated that approximately 22% of human T. gondii infections are meatborne. The objective of the current study was to conduct a systematic meta-analysis to provide a precise estimation of T. gondii infection prevalence in food animals produced in the United States. Four databases were searched to collect eligible studies. Prevalence was estimated in six animal categories (confinement-raised market pigs, confinement-raised sows, non-confinement-raised pigs, lamb, goats, and non-confinement-raised chickens) by a quality-effects model. A wide variation in prevalence was observed in each animal category. Animals raised outdoors or that have outdoor access had a higher prevalence as compared with animals raised indoors. T. gondii prevalence in non-confinement-raised pigs ranked the highest (31.0%) followed by goats (30.7%), non-confinement-raised chickens (24.1%), lambs (22.0%), confinement-raised sows (16.7%), and confinement-raised market pigs (5.6%). These results indicate that T. gondii-infected animals are a food safety concern. The computed prevalence can be used as an important input in quantitative microbial risk assessment models to further predict public health burden.

Toxoplasma gondii infection in meat animals from Africa: Systematic review and meta-analysis of sero-epidemiological studies

“…According to Guo et al . [131], the heterogeneity in prevalence could also be related to the presence of risk factors including farm type, feeding practices, presence of cats, rodent control and bird control methods, farm management, carcasses handling and disposal, and water source and quality. Moreover, studies carried out in distinct countries and various climatic conditions affect the results that could be another reason for this heterogeneity.…”

Infectious immunity in the central nervous system and brain function

“…Among the best known is Toxoplasma gondii , a common zoonotic parasite with a worldwide seroprevalance of 30–70%. T. gondii causes chronic CNS infection and neuroinflammation after ingestion of oocysts in contaminated food or water 115 . Ingested oocysts develop into fast-dividing tachyzoites that invade the gut epithelium and lamina propria, replicate asexually through a process called endodyogeny and then exit and infect myeloid cells, which allow dissemination to multiple tissue sites in the body (including the eye, heart, liver, lung, lymph nodes, muscles and CNS) 116 .…”

Robust Control of a Brain-Persisting Parasite through MHC I Presentation by Infected Neurons

“…The protozoan intracellular parasite Toxoplasma gondii is a widespread foodborne pathogen (Guo et al, 2016), which commonly infects humans. Due to the lack of an effective drug targeting its encysted bradyzoite stage, this parasite cannot be cleared from the brain.…”