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ARS Home » Northeast Area » Beltsville, Maryland (BARC) » Beltsville Agricultural Research Center » Animal Parasitic Diseases Laboratory » Research » Publications at this Location » Publication #354388
Research Project: Detection and Control of Foodborne Parasites for Food Safety

Location: Animal Parasitic Diseases Laboratory

Title: Genetic characterization of Toxoplama gondii DNA samples isolated from humans living in North America: An unexpected high prevalence of atypical genotypes

Author
item POMARES, CHRISTILLE - Palo Alto Medical Foundation Toxoplasma Serology Laboratory
item DEVILLARD, SEBASTIEN - University Of Lyon
item HOLMES, TYSON - Stanford University School Of Medicine
item OLARIU, TUTOR - Stanford University School Of Medicine
item PRESS, CYNTHIA - Palo Alto Medical Foundation Toxoplasma Serology Laboratory
item RAMIREZ, RAYMUND - Palo Alto Medical Foundation Toxoplasma Serology Laboratory
item TALUCOD, JEANNE - Palo Alto Medical Foundation Toxoplasma Serology Laboratory
item ESTRAN, REMY - Victor Babes University Of Medicine And Pharmacy
item SU, CHUNLEI - University Of Tennessee
item Dubey, Jitender
item AIZENBERG, DANIEL - National Reference Center For Toxoplasmosis
item MONTOYA, JOSE - Palo Alto Medical Foundation Toxoplasma Serology Laboratory

Submitted to: Journal of Infectious Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/13/2018
Publication Date: 6/30/2018
Citation: Pomares, C., Devillard, S., Holmes, T.H., Olariu, T.R., Press, C.J., Ramirez, R., Talucod, J., Estran, R., Su, C., Dubey, J.P., Aizenberg, D., Montoya, J.G. 2018. Genetic characterization of Toxoplama gondii DNA samples isolated from humans living in North America: An unexpected high prevalence of atypical genotypes. Journal of Infectious Diseases. 218(11):1783-1791. https://doi.org/10.1093/infdis/jiy375
DOI: https://doi.org/10.1093/infdis/jiy375

Interpretive Summary: Most emerging infectious diseases in humans are zoonoses. Among these pathogens, the zoonotic protozoan parasite T. gondii is perhaps the most ubiquitous, having been identified in the tissues of a variety of animal hosts, including both mammalian and avian species. Toxoplasma gondii is estimated to chronically infect one third of the world’s human population, causing ocular toxoplasmosis in immunocompetent individuals and often-fatal encephalitis in the immunocompromised, as well as birth defects and mortality following vertical transmission to developing fetuses. Globally, this parasite has distinct population structures for each major geographic region examined, with striking contrast between the highly diverse, epidemic structure of the Central/South American region and the more clonal populations found in all other areas, wherein North America, Europe and north Africa, and east Asia are each dominated by particularly clonal genotypes. In the present study, 41 T. gondii DNA samples from patients diagnosed with toxoplasmosis in the United States were genotyped: 18 (43.9%) and 5 (12.2%) were characterized as types II and III, respectively. The remaining 18 genotypes (43.9%) were atypical; first genetic characterization of T. gondii in humans. These results will be of interest to parasitologists, biologists, and microbiologists.

Technical Abstract: Whereas in Europe most of Toxoplasma gondii genotypes belong to the type II lineage, in Latin America, type II is rare and atypical strains predominate. In North America, data on T. gondii genotypes in humans are scarce. In this study, T. gondii DNA samples from 67 patients diagnosed with toxoplasmosis in the United States were available for genotyping. Discriminant analysis of principal components (DAPC) was used to infer each atypical genotype to a geographic area where patients were likely infected. Associations between genotype, disease severity, immune status, and geographic region, were also estimated. Forty-one DNA samples out of 67 were successfully genotyped: 18 (43.9%) and 5 (12.2%) were characterized as types II and III, respectively. The remaining 18 genotypes (43.9%) were atypical and were assigned to a geographic area. Ten genotypes originated from Latin America, 7 from North America and one from Asia (China). In North America, unlike Europe, T. gondii atypical genotypes are common in humans and unlike Latin America, type II strains are still present with significant frequency. Clinicians should be aware that atypical genotypes are common in North America and have been associated with severe ocular and systemic disease and unusual presentations of toxoplasmosis in immunocompetent patients.