title: Validation of the modified agglutination test for the detection of Toxoplasma gondii in free-range chickens by using cat and mouse bioassay.
abstract: The modified agglutination test (MAT) is one of the most commonly used tests for the detection of antibodies to Toxoplasma gondii in animal and human sera. The objective of the present study was to evaluate the diagnostic accuracy of the MAT and bioassay in free-range/backyard (FR) chickens (Gallus domesticus). Previously-published T. gondii test results from 2066 chickens from 19 countries were compiled for the present study. The frequency of isolation of T. gondii increased for MAT titres between 1:5 and 1:160, and ranged from 61 to 75% for antibody titres of 1:160, 1:320, and ⩾1:640. Twenty-three cats fed pooled hearts from a total of 802 FR seronegative (MAT, <1:5) chickens from several countries did not excrete oocysts, indicating a high negative predictive value of MAT because FR chickens would have been exposed to many microbes; cats are the most sensitive indicators of T. gondii infection in tissues and can excrete millions of oocysts after ingesting even a few bradyzoites. Of the 29 cats in this study, six cats, fed hearts pooled from 15-122 FR chickens, excreted oocysts; but these identifications were likely related to misidentification or prozone. Results of the present study support the validity of MAT for the detection of T. gondii infection in chickens.
authors.affiliation: U. S. Department of Agriculture,Agricultural Research Service,Beltsville Agricultural Research Center,Animal Parasitic Diseases Laboratory,Building 1001,Beltsville,Maryland 20705-2350,USA.
authors.forename: J P
authors.initials: JP
authors.lastname: Dubey
authors.affiliation: Department of Health Management,Atlantic Veterinary College,550 University Ave. Charlottetown,Prince Edward Island,C1A 4P3,Canada.
authors.forename: E
authors.initials: E
authors.lastname: Laurin
authors.affiliation: U. S. Department of Agriculture,Agricultural Research Service,Beltsville Agricultural Research Center,Animal Parasitic Diseases Laboratory,Building 1001,Beltsville,Maryland 20705-2350,USA.
authors.forename: O C H
authors.initials: OC
authors.lastname: Kwowk
mesh_terms: D000372:Agglutination Tests / Q000592:standards / Q000662:veterinary*; D000818:Animals; D000913:Antibodies, Protozoan / Q000097:blood; D001681:Biological Assay / Q000592:standards / Q000662:veterinary*; D002415:Cats; D002645:Chickens / Q000469:parasitology*; D005243:Feces / Q000469:parasitology; D051379:Mice; D011201:Poultry Diseases / Q000175:diagnosis*; D015203:Reproducibility of Results; D014122:Toxoplasma / Q000502:physiology; D014124:Toxoplasmosis, Animal / Q000175:diagnosis*
chemical_list: D000913:Antibodies, Protozoan
keywords: Toxoplasma gondii; bioassay; chickens; modified agglutination test