Submitted to: Journal of Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/15/2004
Publication Date: 7/5/2004
Citation: Dubey, J.P., Karhemere, S., Dahl, E., Sreekumar, C., Diabate, A., Dabire, K.R., Vianna, M.C., Kwok, O.C., Lehmann, T. 2004. First biologic and genetic characterization of Toxoplasma gondii isolates from chickens from Africa (Democratic Republic of Congo, Mali, Burkina Faso, and Kenya. Journal of Parasitology. 91(1):69-72. 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, Georgie, report isolation and molecular characterization of Toxoplasma gondii strains from free-range chickens from Africa. These results will be of interest to public health workers, 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. In the present study prevalence of T. gondii in chickens from Democratic Republic of Congo, Mali, Burkina Faso, and Kenya is reported. The prevalence of T. gondii antibodies in sera of 50 free-range chickens from Congo was 50 % based on the modified agglutination test (MAT); antibody titers were 1:5 in 7, 1:10 in 7, 1:20 in 6, 1:40 in 1, 1: 160 or more in 4 chickens. Hearts, pectoral muscles, and brains of 11 chickens with titers of 1: 20 or more were bioassayed individually in mice; T. gondii was isolated from 9; from the hearts of 9, brains of 3, and muscles of 3 chickens. Tissues of each of the 14 chickens with titers of 1:5 or 1:10 were pooled and bioassayed in mice; T. gondii was isolated from 1 chicken with a titer of 1:10. Tissues from the remaining 25 seronegative chickens were pooled and fed to 1 T. gondii-free cat. Feces of the cat were examined for oocysts; the cat did not shed oocysts. The results indicate that T. gondii localizes in the hearts more often than in other tissues of naturally-infected chickens. Genotyping of these 10 isolates using the SAG2 locus indicated that 8 were isolates were Type III, 1 was Type II, and 1 was Type I. Two isolates (1 type I and 1 Type III) were virulent for mice. Toxoplasma gondii was isolated by mouse bioassay from a pool of brains and hearts of 5 of 48 chickens from Mali and 1 of 40 chickens from Burkina Faso; all 6 isolates were avirulent for mice. Genetically, 4 isolates were Type III, and 2 were Type II. Sera were not available from chickens from Mali and Burkina Faso. Toxoplasma gondii antibodies (MAT 100 or more) were found in 4 of 30 chickens from Kisumu, Kenya and T. gondii was isolated from the brain of 1 of 4 seropositive chickens; this strain was avirulent for mice and was type II. This is the first report of isolation and genotyping of T. gondii from any source from these 4 countries in Africa.