Submitted to: Veterinary Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/26/2003
Publication Date: 4/20/2003
Citation: DUBEY, J.P., GRAHAM, D.H., DAHL, E., HILAI, M., EL-GHAYSH, A., SREEUMAR, C., KWOK, O.C., SHEN, S.K., LEHMANN, T. ISOLATION AND MOLECULAR CHARACTERIATOIN OF TOXOPLASMA GONDII FROM CHICKENS AND DUCKS FROM EGYPT. VETERINARY PARASITOLOGY 114:89-95, 2003. Interpretive Summary: Infections by the single-celled parasite Toxoplasma gondii are widely prevalent in humans and animals. Humans become infected by ingesting uncooked meat infected with this parasite or food contaminated with the resistant stage of the parasite (oocyst) excreted in cat feces. Scientists at the Beltsville Agricultural Research Center and an university in Egypt have isolated viable Toxoplasma from 20 of 121 chickens from Egypt. These findings will be of interest to biologists, parasitologists and public health workers.
Technical Abstract: The prevalence of Toxoplasma gondii in free range chickens is a good indicator of the prevalence of T. gondii oocysts in the environment because chickens feed from the ground. In the present study, prevalence of T. gondii in 121 free range chickens (Gallus domesticus) and 19 ducks (Anas sp.) from a rural area surrounding Giza, Egypt was assessed. Blood, heart, and brain from each animal were examined for T. gondii infection. Antibodies to T. gondii, assayed with the modified agglutination test (MAT), were found in 49 (40.4%) chickens in titers of 1:5 in 11, 1:10 in four, 1:20 in four, 1:40 in eight, 1:80 in ten, and 1:160 or more in 12 chickens. Antibodies were found in three ducks each with a titer of 1:80. Hearts and brains of seropositive (MAT ¿1:5) chickens and ducks were bioassayed in mice. Additionally, hearts and brains of seronegative (MAT <1:5) animals were bioassayed in T. gondii-free cats. T. gondii was isolated from 19 of 49 seropositive chickens (one with titer of 1:5, two with titer of 20, one with titer of 40, five with titer of 80, three with titer of 1:160, and seven with titer of ¿ 1:360). One cat fed tissues pooled from 15 seronegative chickens shed T. gondii oocysts, while two cats fed tissues of 34 seronegative chickens did not shed oocysts. T. gondii was isolated form one of the seropositive ducks by bioassay in mice. The two cats fed tissues from 16 seronegative ducks did not shed oocysts. Genotyping of 20 chicken isolates of T. gondii using the SAG 2 locus indicated that 17 isolates were type III and three were type II. The duck isolate of T. gondii was type III. The mice inoculated with tissue stages of all 21 isolates of T. gondii from chickens and ducks remained asymptomatic, indicating that phenotypically they were not type I because type I strains are lethal for mice. Infections with mixed genotypes were not found.