SUMMARYThe prevalence ofToxoplasma gondiiin free-ranging chickens (Gallus domesticus) is a good indicator of the prevalence ofT. gondiioocysts in the soil because chickens feed from the ground. The prevalence ofT. gondiiin 76 free-range chickens from Guyana, South America was determined. Antibodies toT. gondiiwere assayed by the modified agglutination test (MAT), and found in 50 (65·8%) of 76 chickens with titres of 1:5 in four, 1:10 in one, 1:20 in five, 1:40 in seven, 1:80 in six, 1:160 in eight, 1:320 in four, 1:640 or higher in 15. Hearts and brains of 26 chickens with titres of <1:5 were pooled in 5 batches and bioassayed in mice. Hearts and brains of 50 chickens with titres of 1:5 or higher were bioassayed in mice.Toxoplasma gondiiwas isolated by bioassay in mice from 35 chickens with MAT titres of 1:20 or higher. All mice inoculated with tissues of 30 infected chickens remained asymptomatic.Toxoplasma gondiiisolates from 35 chickens were genotyped using 11 PCR-RFLP markers including SAG1, SAG2, SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1, a new SAG2, and Apico. A total of 9 genotypes were identified, with 5 genotypes (nos 1, 4, 5, 6 and 7) unique to Guyana, 2 genotypes (nos 2 and 3) previously identified in chickens from Brazil, 1 genotype (no. 8) previously identified in chickens from Brazil, Costa Rica and Nicaragua, and 1 genotype (no. 9) belonging to the clonal type III lineage that exists globally. Infection with 2 genotypes was found from 1 chicken. This is the first report of genetic characterization ofT. gondiiisolates from any host from Guyana.
Characterization of Toxoplasma gondii Isolates in Free-Range Chickens From Portugal