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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 50 free-range chickens (Gallus domesticus) from Amazon, Brazil, was determined. Antibodies to T. gondii were assayed by the modified agglutination test (MAT) and found in 33 (66%) chickens with titers of 1:5 in 3, 1:10 in 2, 1:20 in 1, 1:40 in 1, 1:80 in 2, 1:160 in 5, 1:200 in 9, 1:400 in 5, 1:800 in 2, 1:1,600 in 2, and 1:3,200 or higher in 1. Hearts and brains of 33 seropositive chickens were bioassayed individually in mice. Tissues from 17 seronegative chickens were pooled and fed to 2 T. gondii-free cats. Feces of cats were examined for oocysts, but none was found. Toxoplasma gondii was isolated from 24 chickens with MAT titers of 1:5 or higher. Genotyping of these 24 T. gondii isolates by polymorphisms at the SAG2 locus indicated that 14 were type I, and 10 were type III; the absence of type II strains from Brazil was confirmed. Fifty percent of the infected mice died of toxoplasmosis, irrespective of the genotype.

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 225 free-range chickens (Gallus domesticus) from Portugal was determined. Antibodies to T. gondii were assayed by the modified agglutination test (MAT) and found in 61 chickens with titers of 1:5 in 8, 1:10 in 6, 1:20 in 3, 1:40 in 23, 1:80 in 5, 1:160 in 4, 1:320 in 8, and 1:640 or higher in 4. Hearts, leg muscles, and brains of 15 seropositive (MAT 1:10 or higher) chickens were bioassayed individually in mice. Tissue from 38 chickens with titers of 1:5 or less were pooled and fed to a T. gondii-free cat. Feces of the cat were examined for oocysts, but none was found. Toxoplasma gondii was isolated from 16 of 19 chickens with MAT titers of 1:10 or higher. Genotyping of 12 of these 16 isolates with polymorphisms at the SAG2 locus indicated that 4 were type III, and 8 were type II. None of the isolates was lethal for mice. Phenotypically, T. gondii isolates from chickens from Portugal were different from those of T. gondii isolates from chickens from Brazil.

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 77 free-range chickens (Gallus domesticus) from Colombia, South America was determined. Antibodies to T. gondii were assayed by the modified agglutination test (MAT), and found in 32 (44.4%) of 72 chickens with titers of 1:5 in 4, 1:10 in 3, 1:20 in 1, 1:40 in 1, 1:80 in 8, 1:160 in 8, 1:320 in 3, and 1:640 or higher in 4. Hearts and brains of 31 seropositive chickens were pooled and bioassayed in mice. Tissues from 32 (16+16) seronegative chickens were pooled and fed to two, T. gondii-free cats, and tissues from nine chickens without matching sera were fed to one T. gondii-free cat. Feces of cats were examined for oocysts. T. gondii oocysts were excreted by a cat that was fed tissues of 16 seronegative chickens. T. gondii was isolated by bioassay in mice from 23 chickens with MAT titers of 1:20 or higher. All infected mice from 16 of the 23 isolates died of toxoplasmosis. Overall, 82 (81.1%) of 101 mice that became infected after inoculation with chicken tissues died of toxoplasmosis. Genotyping of these 24 isolates using polymorphisms at the SAG2 locus indicated that seven T. gondii isolates were Type I, 17 were Type III, and none was Type II. Phenotypically, T. gondii isolates from chickens from Colombia were similar to isolates from Brazil but different from the isolates from North America; most isolates from chickens from Brazil and Colombia were lethal for mice whereas isolates from North America did not kill inoculated mice. Genetically, none of the T. gondii isolates from Colombia and Brazil was SAG2 Type II, whereas most isolates from chickens from North America were Type II. This is the first report of genetic characterization of T. gondii isolates from Colombia, South America.

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 free-range chickens (Gallus domesticus) from 11 Bio-farms in Austria was determined. Antibodies to T. gondii assayed by the modified agglutination test (MAT) were found in 302 of 830 (36.3%) chickens with titers of 1:10 in 50, 1:20 in 69, 1:40 in 53, 1:80 in 40, 1:160 or higher in 90. Hearts of 218 chickens with MAT titers of 10 or higher were bioassayed individually in mice. Tissues from 1183 chickens were pooled and fed to 15, T. gondii-free cats. Feces of the cats were examined for oocysts; 11 cats shed T. gondii oocysts. T. gondii was isolated from 56 chickens by bioassay in mice. Thus, there were 67 isolates of T. gondii from these chickens. Genotyping of these 67 isolates using the SAG2 locus indicated that all 33 were Type II. Phenotypically and genetically these isolates were different from T. gondii isolates from Brazil. None of the isolates was virulent for mice. This is the first report of isolation of T. gondii from chickens from Austria.

The prevalence of Toxoplasma gondii in free-range 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 greater in 2. Hearts, pectoral muscles, and brains of 43 seropositive chickens with MAT titers of 1:20 or greater 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. T. gondii was isolated from 35 of 43 chickens with MAT titers of 1:20 or greater; from the hearts, brains, and pectoral muscles of 2, hearts and brains of 20, from the hearts alone of 11, and brains alone of 2. T. 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 these 36 isolates using polymorphisms at the SAG2 locus indicated that 29 were Type III, 5 were Type I, 1 was Type II, and 1 had both Type I and Type III. Genetically, the isolates from Grenada were different from those from the United States; Type II was the predominant type from the United States. Phenotypically, all isolates from Grenada were avirulent for mice, whereas those from Brazil were mouse-virulent. This is the first report of isolation of T. gondii from chickens from Grenada, West Indies.

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, and 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, but none was seen. 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 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 on isolation and genotyping of T. gondii from any source from these 4 countries in Africa.

Little is known of the prevalence of Toxoplasma gondii in commercially raised chickens. In the present study, the prevalence of T. gondii in 96 free-range chickens (Gallus domesticus) from a commercial farm in Israel was assessed. Blood, heart, and brain from each chicken were examined for T. gondii infection. Antibodies to T. gondii, assayed with the modified agglutination test (MAT > or = 1:5), were found in 45 of the 96 chickens. Hearts and brains of seropositive (MAT > or = 1:5) chickens were bioassayed in mice. Additionally, hearts and brains of 51 seronegative (MAT < 1:5) chickens were bioassayed in two T. gondii-free cats. T. gondii was isolated from 19 of the 45 (42.2%) seropositive chickens by bioassay in mice. Both the cats fed tissues pooled from seronegative chickens shed T. gondii oocysts. Tachyzoites and tissue cysts of all 21 isolates of T. gondii from chickens were avirulent for mice. Seventeen of the 19 isolates genotyped were found to be type II, and 2 were type III. Understanding of the sources of infection on such farms could be the key to the development of better prevention strategies.

The present study was undertaken to isolate and genotype Toxoplasma gondii from free-range chickens (Gallus domesticus) from villages in Maharashtra and Tamil Nadu states of central and south India, respectively. Blood, heart, and brain from a total of 741 chickens were examined for T. gondii infection. Antibodies to T. gondii, as assayed with the modified agglutination test (MAT >or = 1:5) were found in 133 (17.9%) chickens. Hearts and brains of 186 chickens were bioassayed in mice. Additionally, hearts and/or brains of most of the seronegative (MAT < 1:5) chickens were fed to 20 T. gondii-free cats, while 32 seropositive chickens (MAT 1:5) were fed to 3 cats. T. gondii was not isolated from any of the chickens by mouse bioassay. Five of the cats that were fed seronegative chickens shed oocysts, while isolates were not obtained from any of the other cats fed seropositive chickens. These five isolates, along with the two that were previously isolated in India through cat bioassay, were genetically analyzed. Genotyping using the SAG 2 locus indicated that two isolates were type II and five were type III. Microsatellite analysis revealed allelic differences between and within the lineages. This is the first report of genetic characterization of any T. gondii isolate from India.

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 40 free range chickens (Gallus domesticus) from a rural area surrounding Paraná, Brazil was assessed. Blood, heart, and brain from each chicken were examined for T. gondii infection. Antibodies to T. gondii, assayed with the modified agglutination test (MAT> or =1:5) were found in 16 chickens. Hearts and brains of seropositive (MAT> or =1:5) chickens were bioassayed in mice. Additionally, hearts and brains of seronegative (MAT<1:5) chickens were bioassayed in two T. gondii-free cats (12 chickens per cat). T. gondii was isolated from 13 of 16 (81%) seropositive chickens. Of the two cats fed tissues pooled form seronegative chickens, one shed T. gondii oocysts. Nine of the 13 T. gondii isolates killed 100% of infected mice. The T. gondii isolate from the cat was also virulent for mice. Genotyping of 13 chicken isolates of T. gondii using the SAG2 locus indicated that seven isolates were type I and six were type III; three of these type III isolates killed all infected mice suggesting that all strains virulent for mice are not type I. The isolate from the feces of the cat fed chicken tissues was type I.

The prevalence of Toxoplasma gondii in free-ranging chickens can be considered 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 29 free-range chickens (Gallus domesticus) from Argentina was investigated. Blood, heart, and brain from each chicken were examined for T. gondii infection. Antibodies to T. gondii, assayed with the modified agglutination test (MAT), were found in 19 of 29 (65.5%) chickens. Hearts and brains of seropositive (MAT > or = 1:5) chickens were bioassayed in mice. Toxoplasma gondii was isolated from 9 of 19 seropositive chickens. Genotyping of chicken isolates of T. gondii using the SAG2 locus indicated that 1 was type I, 1 was type II, and 7 were type III. This is the first report of isolation of T. gondii from chickens from Argentina.

This article presents a study on the prevalence of viable Toxoplasma gondii in beef, chicken and pork from retail meat stores in the U.S. The prevalence of viable Toxoplasma gondii was determined in 6,282 samples obtained from 698 retail meat stores from 28 major geographic areas. Each sample consisted of a minimum of 1 kilogram of meat purchased from the retail meat case.