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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 #396103

Research Project: Foodborne Parasites and their Impact on Food Safety

Location: Animal Parasitic Diseases Laboratory

Title: Toxoplasma gondii clonal type III is the dominant genotype identified in Grenadian pigs

item CHIKWETO, ALFRED - St George'S University
item ALHASSAN, ANDY - St George'S University
item CHUNLEI, SU - University Of Tennessee
item MACPHERSON, CALUM - St George'S University
item BHAIYAT, MUHAMMAD - St George'S University
item Dubey, Jitender

Submitted to: Veterinary Medicine and Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/1/2022
Publication Date: 7/9/2022
Citation: Chikweto, A., Alhassan, A., Chunlei, S., Macpherson, C., Bhaiyat, M., Dubey, J.P. 2022. Toxoplasma gondii clonal type III is the dominant genotype identified in Grenadian pigs. Veterinary Medicine and Science.

Interpretive Summary: Food safety is a worldwide concern. Among these zoonotic pathogens, the single celled parasite Toxoplasma gondii is perhaps the most ubiquitous, having been identified in virtually all warm- blooded animals and humans. Toxoplasma gondii can cause serious illness in humans and animals, including birth defects. Humans become infected postnatally by eating undercooked meat infected with T. gondii tissue cysts or by ingesting oocysts from the environment. Cats (domestic and wild) are the main reservoir of infection because they are the only hosts that can excrete the environmentally resistant stage, the oocyst. Pigs are important in the life cycle and epidemiology of T. gondii because they serve as sources of infection for humans in many countries. Here, the authors report first isolation and genetic characterization of viable Toxoplasma from pigs in Grenada, West Indies. This research was completed in 2018, before the redirection of Toxoplasma research at USDA.

Technical Abstract: Toxoplasma gondii is a widespread zoonotic protozoan parasite capable of infecting all warm-blooded animals. Although the genotypes of T. gondii in pigs have been reported worldwide, there is no information on the genotypes and diversity of T. gondii in pigs in Grenada, West Indies. Objectives: The aims of the present study were to isolate, genotype and determine the diversity of T. gondii genotypes in pigs. Methods: We carried out a modified agglutination test (MAT) on blood from 149 pig hearts collected from a local meat market. Myocardial tissue homogenate from pigs that tested positive for T. gondii was homogenized and inoculated into mice for isolation of the parasite. We collected mouse tissues and extracted DNA for genotyping based on 11 polymerase chain reaction-restriction fragment length polymorphism markers (SAG1, SAG2, alt. SAG2, SAG 3, BTUB, GRA6, L358, PK1, C22-8, C 29-2 and Apico). Results: Out of the 149 pig hearts, 31 (20.8%) tested positive for T. gondii on MAT. Bioassays in mice yielded 12 isolates designated TgpgGr1 to TgpgGr12. Molecular characterization of T. gondii revealed four genotypes as follows: ToxoDB #2-clonal type III (seven isolates); ToxoDB #7 (three isolates); ToxoDB #13 (one isolate); ToxoDB #30 (1 isolate). Overall, ToxoDB #2 was the most common (58%). Toxo database (DB) # 13, which causes interstitial pneumonia in affected mice, has also been reported. Conclusion: The genetic diversity of T. gondii in pigs in Grenada is lower than that in other surrounding Caribbean areas.