Current Status of Avian Toxoplasmosis in the World: A Systematic Review and Meta-analysis

Toxoplasmosis is a food-borne disease that infects almost all warm-blooded mammals and birds. Birds are considered intermediate hosts for the parasite. The consumption of infected birds by humans and other animals plays a highlight role in the transmission of this parasite. Accordingly, the present review was conducted to find the global seroprevalence of T. gondii in birds.

A comprehensive search of five academic databases (ScienceDirect, PubMed, Web of Science, ProQuest, and Scopus) and Google Scholar was conducted for literature published from 1952 to December 13, 2020.

Finally, a total of 211 studies, including 69006 birds (from 61 countries), were incorporated in the present study. The seroprevalence was calculated at 27.96% (95% CI=25.27-30.73) based on the random effect. The pooled seroprevalence rates of T. gondii were in Africa (39.73%), America (34.50%), Asia (23.65%), and Europe (17.46%). Based on these results, the Modified Agglutination Test (MAT) was the most common diagnostic method (122 studies). The weighted prevalence was higher in free-range chickens (37.60%) and domestic chickens (36.93%) than in other bird types.

Based on the findings of the study, a high seropositivity of T. gondii in birds indicates that they could be a potential food safety risk for humans.

The current review has contributed to enhancing the understanding of the relatively high level of T. gondii seroprevalence in birds. The results from this study are useful for policymakers to control T. gondii infection in meat consumption, due to the significant role of poultry in the human diet.