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United States Department of Agriculture

Agricultural Research Service

Research Project: INTEGRATED APPROACH TO THE DETECTION AND CONTROL OF FOODBORNE PARASITES AND THE IMPACT ON FOOD SAFETY

Location: Animal Parasitic Diseases

Title: Geographical patterns of Toxoplasma gondii genetic diversity revealed by multilocus PCR-RFLP genotyping

Authors
item Shwab, Keats -
item Zhu, Xian-Quan -
item Majumdar, Debashree -
item Pena, Hilda -
item Gennari, Solange -
item Dubey, Jitender
item Su, Chunlei -

Submitted to: Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 1, 2013
Publication Date: December 1, 2013
Citation: Shwab, E.K., Zhu, X., Majumdar, D., Pena, H.F.J., Gennari, S., Dubey, J.P., Su, C. 2013. Geographical patterns of Toxoplasma gondii genetic diversity revealed by multilocus PCR-RFLP genotyping. Parasitology. 141: 453-461.

Interpretive Summary: Toxoplasma gondii is a single-celled parasite of all warm-blooded hosts worldwide. It causes mental retardation and loss of vision in children, and abortion in livestock. Cats are the main reservoir of T. gondii because they are the only hosts that can excrete the resistant stage (oocyst) of the parasite in the feces. Humans become infected by eating under cooked meat from infected animals and food and water contaminated with oocysts. Why some hosts/persons infected with Toxoplasma become sick whereas most remain asymptomatic is unknown. Recently, attention has been focussed on genetic diversity of Toxoplasma. In the present study, authors review all available information on genetic diversity using one system of classification. The results will be of interest to biologists and parasitologists.

Technical Abstract: In recent years, an extensive collection of Toxoplasma gondii samples have been typed by the multilocus PCR-RFLP method using a standardized set of 10 genetic markers. Here we summarize the data reported until the end of 2012. A total of 1457 samples were typed into 189 genotypes. Overall, only a few genotypes dominate in the northern hemisphere, which is in stark contrast to the southern hemisphere where hundreds of genotypes coexist with none being notably dominant. PCR-RFLP genotype #1 (Type II clonal), #2 (Type III), #3 (Type II variant) and #10 (Type I) are identified globally. Genotypes #2 and #3 dominate in Africa, genotypes #9 (Chinese 1) and #10 are prevalent in Asia, genotypes #1, #2 and #3 are highly prevalent in Europe, genotypes #1, #2, #3, #4 and #5 dominate in North America (#4 and #5 are collectively known as type 12). In Central and South America, there is no clear dominance of any genotype even though a few have been detected with relatively higher frequencies. Statistical analysis indicates that there are significant differences among populations in Africa, Asia, Europe, North America, and Central and South America, with only the populations of Europe and North America exhibiting similar diversity to each other. Collectively, the results revealed distinct population structures and geographical patterns of diversity in T. gondii.

Last Modified: 8/22/2014
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