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United States Department of Agriculture

Agricultural Research Service


item Dubey, Jitender
item Su, C
item De Ikuverua, Jaqueline
item Morales, Juan
item Bolanos, Rafael
item Sundar, N
item Kwok, Oliver
item Shen, Samuel

Submitted to: Veterinary Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/4/2006
Publication Date: 6/6/2006
Citation: Dubey, J.P., Su, C., De Ikuverua, J.B., Morales, J.A., Bolanos, R.V., Sundar, N., Kwok, O.C., Shen, S.K. 2006. Biologic and genetic characteristics of toxoplasma gondii isolates in free-range chickens from costa rica, central america. Veterinary Parasitology. 139:29-36.

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 undercooked meat from infected animals and food and water contaminated with oocysts. Scientists at the Beltsville Agricultural Research Center and Univ. of Costa Rica have found that T. gondii infection is widely prevalent in chickens from Costa Rica. The results will be of interest to biologists, parasitologists, and veterinarians.

Technical Abstract: The prevalence of Toxoplasma gondii in free-ranging chickens is a good indicator of the prevalence of T. gondii oocysts in the soil because chickens feed from the ground. The prevalence of T. gondii in 94 free-range chickens (Gallus domesticus) from Costa Rica was determined. Antibodies to T. gondii were assayed by the modified agglutination test (MAT), and found in 30 (31.9%) of 94 chickens with titers of 1:5 in 10, 1:10 in three, 1:20 in one, 1: 40 in one , 1: 80 in four, 1:160 in two, 1:320 in six, and 1: 640 or higher in three. Hearts and brains of 30 chickens with titers of 1:5 or higher and 16 chickens with doubtful titers were pooled and bioassayed in mice. Tissues from 48 seronegative (MAT <1:5) chickens were pooled and fed to one T. gondii-free cat. Feces of the cat were examined for oocysts but none was found. T. gondii was isolated by bioassay in mice from 12 chickens with MAT titers of 1:10 or higher. All infected mice from four of the 12 isolates died of toxoplasmosis. Overall, 57.4% of 47 mice that became infected after inoculation with chicken tissues died of toxoplasmosis. Genotyping of these 12 isolates using polymorphisms at the loci SAG1, SAG2, SAG3, BTUB and GRA6 revealed five genotypes. Five isolates had type I alleles and one isolate had type III alleles at all loci. The rest six isolates contained the combination of type I and II or I and III alleles and were divided into three genotypes. None was found to have genotype II alleles at all five loci. This is the first report of genetic characterization of T. gondii isolates from Costa Rica, Central America.

Last Modified: 10/18/2017
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