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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 #336347

Research Project: Detection and Control of Foodborne Parasites for Food Safety

Location: Animal Parasitic Diseases Laboratory

Title: Prevalence and genetic characterization of Toxoplasma gondii in free-range chickens from grocery stores and farms

item YING, YUQING - University Of Maryland
item VERMA, SHIV - Non ARS Employee
item Kwok, Oliver
item ALIBANA, FATIMA - University Of Chicago
item MCLEOD, RIMA - University Of Chicago
item SU, CHUNLEI - University Of Tennessee
item Dubey, Jitender
item PRADHAN, ABANI - University Of Maryland

Submitted to: Parasitology Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/3/2017
Publication Date: 3/24/2017
Citation: Ying, Y., Verma, S.K., Kwok, O.C., Alibana, F., Mcleod, R., Su, C., Dubey, J.P., Pradhan, A.K. 2017. Prevalence and genetic characterization of Toxoplasma gondii in free-range chickens from grocery stores and farms. Parasitology Research. 116:1591-1595.

Interpretive Summary: Human toxoplasmosis, caused by single-celled parasite, Toxoplasma gondii, accounts for an estimated one-fifth of all diagnosed foodborne infections in the United States, and one fifth of the economic costs attributable to any foodborne pathogen. Pregnant women and their fetuses are exposed to elevated health risks. The ingestion of under cooked infected meat is considered an important source of toxoplasmosis in humans. Poultry is important in the transmission of Toxoplasma both as direct source of infection for humans, and indirectly as prey for the reservoir host, cats. Cats can excrete millions of environmentally resistant stage (oocyst) in their feces. Humans can acquire toxoplasmosis by ingesting food and water contaminated with oocysts. In the present study chicken hearts (n=1185) obtained from the local markets were tested for T. gondii infection. Although low levels of antibodies were found in 230 , viable Toxoplasma was not isolated from any of the 230 seropositive chickens bioassayed. Results indicate low risk of acquiring toxoplasmosis from chickens sold in grocery stores. The results will be of interests to parasitologists, public health workers and biologists.

Technical Abstract: Chickens are considered important in the epidemiology of Toxoplasma gondii. Chicken hearts (n=1185) obtained from the local markets were tested for T. gondii infection. Antibodies to T. gondii were assayed in fluid removed from the heart cavity using the modified agglutination test (MAT) at 1:5, 1:25, and 1: 100 dilutions. MAT antibodies were detected in 222 hearts at 1:5 dilution, 8 hearts at 1:25 dilution, but none were positive at 1:100 dilution. Seropositive (n=230) chicken hearts were bioassayed in mice and seronegative (n=157) chickens were bioassayed in cats. Viable T. gondii was not isolated from any hearts by bioassays in mice. The 2 cats fed 60 and 97 hearts did not excrete T. gondii oocysts. The results indicate a low prevalence of T. gondii in chickens from grocery stores. Molecular typing of 13 archived T. gondii strains isolated from free-range chickens from Ohio and Massachusetts using the PCR-RFLP markers including SAG1, SAG2 (5’-3’SAG2 and altSAG2), SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1, and Apico revealed that five were ToxoDB PCR-RFLP genotype #1, four were genotype #2, 1 was genotype #3, and three were a new genotype #268. This new genotype differs from genotype #2 only at the locus BTUB, suggesting they are closely related. These results indicate that the clonal genotypes #1 (Type II), #2 (Type III) and #3 (Type II variant) are common in free-range chickens, and the genetic diversity of T. gondii in this domestic animal is limited.