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Submitted to: Veterinary Parasitology
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 7/15/2006 Publication Date: 1/1/2007 Citation: Dubey, J.P., Sundar, N., Gennari, S.M., Minervino, A.H., Farias, N., Ruas, J.L., Santos, T., Cavalcante, G.T., Kwok, O.C., Su, C. 2007. Biologic and genetic comparison of Toxoplasma gondii isolates in free-range chickens from the northern pará state and the southern state Rio Grande do Sul, Brazil revealed highly diverse and distinct parasite populations. Veterinary Parasitology. 143:182-188. 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.Toxoplasmosis causes mortality in many species of animals in the zoos, especially primates. Scientists at the Beltsville Agricultural Research Center and University of Sao Paulo, Brazil, South America report genetic characterization of Toxoplasma from chickens from Brazil. The results will be of interest to biologists, parasitologists, and veterinarians Technical Abstract: The prevalence of Toxoplasma gondii in free-ranging chickens (Gallus domesticus) 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 84 free-range chickens (34 from the northern Pará state, and 50 from Rio Grande do Sul, the southern state) from Brazil, South America was determined. Antibodies to T. gondii were assayed by the modified agglutination test (MAT), and found in 39 (46.4%) of 84 chickens with titers of 1:10 in one, 1:20 in two, 1: 40 in four, 1: 80 in seven, 1:160 in five, 1:320 in six, 1:640 in eight, and '1:1280 in six. Hearts and brains of 44 chickens with titers of 1:20 or less were pooled and fed to two T. gondii-free cats. Hearts and brains of 39 chickens with titers of 1:20 or higher were bioassayed in mice. Feces of cats were examined for oocysts. One cat fed tissues from 31 chickens with titers of less than 1:10 from Rio Grande do Sul shed T. gondii oocysts. T. gondii was isolated by bioassay in mice from 33 chickens with MAT titers of 1:20 or higher. All infected mice from 10 isolates died of toxoplasmosis. All 34 isolates (15 from Pará, 19 from Rio Grande do Sul) were genotyped using 11 nuclear markers including SAG1, SAG2, SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1, a new SAG2 and Apico. Eleven genotypes were revealed for Pará isolates and seven genotypes for Rio Grande do Sul. No genotype was shared between the two geographical locations. These data suggests that T. gondii isolates are highly diverse and genetically distinct between the two different regions in Brazil that are 4500 km apart. |
