Submitted to: Journal of Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/1/2010
Publication Date: 9/1/2010
Citation: Dubey, J.P., Chellaiah, R., Costa, D.G., Ferreria, L.R., Kwok, O.C., Qu, D., Su, C., Marvulo, M.F., Alves, L.C., Mota, R.A., Silva, J.C. 2010. New Toxoplasma gondii genotypes isolated from free-range chickens from the Fernando de Noronha, Brazil: unexpected findings. Journal of Parasitology. 96:709-712. 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. This paper reports on new genetic types of Toxoplasma from chickens. The results will be of interest to biologists, parasitologists, public health workers, and veterinarians.
Technical Abstract: Worldwide comparison of Toxoplasma gondii isolates from free range chickens has indicated that T. gondii isolates from Brazil are phenotypically and genetically different than isolates from other countries; most strains from Brazil are pathogenic to mice, there is great genetic variability, most isolates are non clonal, and Type II is absent or rare. The prevalence of T. gondii in 50 free-range chickens (Gallus domesticus) from the island of Fernando de Noronha, Brazil (this island is 350 kilometers from the mainland) was determined. Antibodies to T. gondii were assayed by the modified agglutination test (MAT); 42 (84 %) chickens had titers of 1:5 in 2, 1:10 in 4, 1:20 in 3, 1: 40 in 6, 1: 80 in 6, 1: 160 in 5, 1:320 in 3, and 1: 640 or higher in 13. Hearts of 40 seropositive chickens were bioassayed individually in mice. Toxoplasma gondii was isolated from 24 chickens with MAT titers of 1:5 or higher; the isolates were designated TgCKBr210-233. None of the isolates was pathogenic for mice. The restricted fragment length polymorphism using 10 markers revealed 6 genotypes, including the clonal type II, type III and 4 new genotypes (#1-#4) that were different from genotypes so far reported in Brazil. All 24 isolates were successfully genotyped, 15 isolates were type #1, 1 type #2, 1 type #3, 1 type #4, 5 were clonal Type II (with type I allele at the Apico locus), and 1 isolate was clonal Type III. Results in this study indicate that T. gondii on this island consists of unique genotypes as well as clonal genotypes that are dominant in Europe and North America.