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Review
. 2022 Feb 27;10(3):517.
doi: 10.3390/microorganisms10030517.

Contamination of Soil, Water, Fresh Produce, and Bivalve Mollusks with Toxoplasma gondii Oocysts: A Systematic Review

Nadia María López Ureña  1 , Umer Chaudhry  2 , Rafael Calero Bernal  1 , Santiago Cano Alsua  3 , Davide Messina  2   4 , Francisco Evangelista  2 , Martha Betson  2 , Marco Lalle  5 , Pikka Jokelainen  6 , Luis Miguel Ortega Mora  1 , Gema Álvarez García  1
Affiliations
Review

Contamination of Soil, Water, Fresh Produce, and Bivalve Mollusks with Toxoplasma gondii Oocysts: A Systematic Review

Nadia María López Ureña et al. Microorganisms. .

Abstract

Toxoplasma gondii is a major foodborne pathogen capable of infecting all warm-blooded animals, including humans. Although oocyst-associated toxoplasmosis outbreaks have been documented, the relevance of the environmental transmission route remains poorly investigated. Thus, we carried out an extensive systematic review on T. gondii oocyst contamination of soil, water, fresh produce, and mollusk bivalves, following the PRISMA guidelines. Studies published up to the end of 2020 were searched for in public databases and screened. The reference sections of the selected articles were examined to identify additional studies. A total of 102 out of 3201 articles were selected: 34 articles focused on soil, 40 focused on water, 23 focused on fresh produce (vegetables/fruits), and 21 focused on bivalve mollusks. Toxoplasma gondii oocysts were found in all matrices worldwide, with detection rates ranging from 0.09% (1/1109) to 100% (8/8) using bioassay or PCR-based detection methods. There was a high heterogeneity (I2 = 98.9%), which was influenced by both the sampling strategy (e.g., sampling site and sample type, sample composition, sample origin, season, number of samples, cat presence) and methodology (recovery and detection methods). Harmonized approaches are needed for the detection of T. gondii in different environmental matrices in order to obtain robust and comparable results.

Keywords: Toxoplasma gondii; bivalve mollusk; environment; fresh produce; fruit; methodology; oocysts; sampling strategy; soil; water.

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Conflict of interest statement

M.L. is guest editor for Microorganisms, Special Issue “Advances in the Diagnosis, Detection, Epidemiology, and Control of Toxoplasma gondii”, but he had no role in the editorial handling of the current manuscript. The other authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Four-step flow diagram of the systematic review of the presence of Toxoplasma gondii oocysts in soil, water, vegetables, fruit, and bivalve mollusks worldwide until the end of 2020.
Figure 2
Figure 2
Worldwide detection of Toxoplasma gondii oocysts in environmental matrices based on molecular methods (PCR, qPCR, and LAMP) in studies published by the end of 2020. Results are presented as positive samples/total of samples collected. Articles that analyzed pooled samples and did not specify how the number of positive individual samples was estimated were excluded.
Figure 3
Figure 3
Workflow and key considerations for standard sampling strategies and detection methods for Toxoplasma gondii in environmental matrices.
See this image and copyright information in PMC

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