Dubey J P, Lenhart A, Castillo C E, Alvarez L, Marcet P, Sreekumar C, Lehmann T
United States Department of Agriculture, Agricultural Research Service, Animal and Natural Resources Institute, Animal Parasitic Diseases Laboratory, Beltsville, Maryland 20705-2350, USA.
J Parasitol. 2005 Dec;91(6):1332-4. doi: 10.1645/GE-500R.1.
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 46 free-range chickens (Gallus domesticus) from Venezuela was determined. Antibodies to T. gondii were assayed by the modified agglutination test (MAT). Antibodies were found in 16 (32%) chickens with titers of 1:5 in 1, 1:10 in 2, 1:40 in 2, 1:80 in 2, 1:160 in 2, 1:320 in 3, 1: 640 in 2, and 1:1,280 or higher in 2. Hearts, pectoral muscles, and brains of 13 chickens with MAT titers of 1:40 or more were bioassayed individually in mice. Tissues of each of 3 chickens with titers of 1:5 or 1:10 were pooled and bioassayed in mice. Tissues from the remaining 30 seronegative chickens were pooled and fed to 1 T. gondii-free cat. Feces of the cat were examined for oocysts; it did not shed oocysts. Toxoplasma gondii was isolated from 12 of 13 chickens with MAT titers of 1:40 or more. Toxoplasma gondii was isolated from pooled tissues of 1 of 2 chickens with titers of 1:10. Eight of these 13 isolates were virulent for mice. Genotyping of 13 of these isolates using the SAG2 locus indicated that 10 were type III, and 3 were type II. Phenotypically and genetically these isolates were different from T. gondii isolates from North America and Brazil. This is the first report of isolation of T. gondii from chickens from Venezuela.
散养家禽体内弓形虫的感染率是土壤中弓形虫卵囊感染率的良好指标，因为家禽在地面觅食。测定了委内瑞拉46只散养家禽（家鸡）体内弓形虫的感染率。采用改良凝集试验（MAT）检测鸡血清中抗弓形虫抗体。在16只（32%）鸡中检测到抗体，抗体效价分别为：1只鸡为1:5，2只鸡为1:10，2只鸡为1:40，2只鸡为1:80，2只鸡为1:160，3只鸡为1:320，2只鸡为1:640，2只鸡为1:1280或更高。对13只MAT效价为1:40及以上的鸡的心脏、胸肌和大脑分别在小鼠体内进行生物测定。将3只效价为1:5或1:10的鸡的组织混合后在小鼠体内进行生物测定。将其余30只血清学阴性鸡的组织混合后喂给1只未感染弓形虫的猫。检查猫的粪便中是否有卵囊；未发现排出卵囊。从13只MAT效价为1:40及以上的鸡中的12只鸡中分离出弓形虫。从2只效价为1:10的鸡中的1只鸡的混合组织中分离出弓形虫。这13株分离株中有8株对小鼠具有致病性。利用SAG2基因座对其中13株分离株进行基因分型，结果表明10株为III型，3株为II型。从表型和基因方面来看，这些分离株与来自北美和巴西的弓形虫分离株不同。这是首次从委内瑞拉鸡中分离出弓形虫的报告。
