Submitted to: Journal of Parasitology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 9/30/2004
Publication Date: 10/30/2004
Citation: Dubey, J.P., Bhalyat, M.I., Miska, K.B., Macpherson, C.N., Sharma, R.N., Sreekumar, C., Hill, D.E., Shen, S.K., Kwok, O.C., Lehmann, T. 2004. Isolation, tissue distribution, and molecular characterization of toxoplasma gondii from chickens from Grenada, West Indies. Journal of Parasitology. 91(3):557-560. Interpretive Summary: Infection by the single-celled parasite, Toxoplasma gondii, is common in man and animals. Humans become infected by eating undercooked infected meat or ingesting the resistant stage of Toxoplasma (oocysts) in the environment. Infections in free range-range chickens is indicative of Toxoplasma infection in the environment because chickens feed from the ground. Scientists at the Beltsville Agricultural Research Center and Centers for Disease Control, Atlanta, Georgia, report isolation and molecular characterization of Toxoplasma gondii strains from free-range chickens from Grenada, West Indies. These results will be of interest to public health workers, 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 102 free-range chickens (Gallus domesticus) from Grenada was determined. Antibodies to T. gondii were assayed by the modified agglutination test (MAT). Antibodies were found in 53 ( 52%) chickens with titers of 1:5 in 6, 1: 10 in 4, 1:20 in 4, 1: 40 in 4, 1: 80 in 15, 1: 160 in 9, 1: 320 in 5, 1: 640 in 4, and 1: 1,280 or more in 2. Hearts, pectoral muscles, and brains of 43 seropositive chickens with MAT titers of 1:20 or more were bioassayed individually in mice. Tissues of each of 10 chickens with titers of 1:5 and 1:10 were pooled and bioassayed in mice. Tissues from the remaining 49 seronegative chickens were pooled and fed to 4 T. gondii-free cats. Feces of cats were examined for oocysts; they did not shed oocysts. Toxoplasma gondii was isolated from 35 of 43 chickens with MAT titers of 1:20 or more; from the heart, brain and pectoral muscle of 2, hearts and brains of 20, from the hearts alone of 11, and brain alone of 2. Toxoplasma gondii was isolated from 1 of 10 chickens with titers of 1:5 or 1:10. All 36 T. gondii isolates were avirulent for mice. Genotyping of 31 of these 36 isolates using the SAG2 locus indicated that 27 were Type III and 4 were Type I. Genetically, the isolates from Grenada were different from those from the USA; Type II was not found, whereas Type II was the predominant type from the USA. Phenotypically, Type I and III isolates from Grenada were avirulent for mice while those from Brazil were mouse virulent. This is the first report of isolation of T. gondii from chickens from Grenada, West Indies.