Dubey J P, Marcet Paula L, 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):1335-9. doi: 10.1645/GE-575R.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 61 free-range chickens (Gallus domesticus) from provinces of Santiago del Estero and Entre Rios, Argentina was determined. Antibodies to T. gondii were assayed by the modified agglutination test (MAT) and were found in 25 chickens; titers were 1:5 in 6 chickens, 1:10 in 1 chicken, 1:20 in 2 chickens, 1:40 in 1 chicken, 1:80 in 2 chickens, 1:60 in 4 chickens, 1:120 in 2 chickens, 1:640 in 3 chickens, and 1: 1,280 or higher in 4 chickens. Hearts, pectoral muscles, and brains of 22 seropositive (MAT 1:10 or higher) chickens were bioassayed individually in mice. Tissue from 39 chickens with titers of 1:5 or less were pooled and fed to 3 T. gondii-free cats. Feces of cats were examined for oocysts, but none was found. Toxoplasma gondii was isolated from 17 of 22 chickens with MAT titers of 1:10 or higher. Genotyping of these 17 isolates using polymorphisms at the SAG2 locus indicated that 4 were Type I, 3 were Type II, and 10 were Type III. Toxoplasma gondii isolates (2 Type I and I Type III) from 3 chickens were virulent for mice and 1 Type I was not mouse virulent. Prevalence of T. gondii antibodies in chickens varied among regions, being 3 times greater in the humid Pampeana region (61.2%) than in the semiarid plain of Santiago del Estero (20%).
散养鸡中弓形虫的流行情况是土壤中弓形虫卵囊流行情况的良好指标，因为鸡在地面觅食。测定了来自阿根廷圣地亚哥 - 德尔埃斯特罗省和恩特雷里奥斯省的61只散养鸡（家鸡）中弓形虫的流行情况。采用改良凝集试验（MAT）检测弓形虫抗体，在25只鸡中检测到抗体；6只鸡的滴度为1:5，1只鸡为1:10，2只鸡为1:20，1只鸡为1:40，2只鸡为1:80，4只鸡为1:60，2只鸡为1:120，3只鸡为1:640，4只鸡为1:1280或更高。对22只血清阳性（MAT 1:10或更高）鸡的心脏、胸肌和大脑分别在小鼠中进行生物测定。将39只滴度为1:5或更低的鸡的组织混合后喂给3只无弓形虫的猫。检查猫的粪便中的卵囊，但未发现。从22只MAT滴度为1:10或更高的鸡中的17只分离出弓形虫。利用SAG2位点的多态性对这17株分离株进行基因分型，结果表明4株为I型，3株为II型，10株为III型。从3只鸡中分离出的弓形虫分离株（2株I型和1株III型）对小鼠具有致病性，1株I型对小鼠无致病性。鸡中弓形虫抗体的流行率因地区而异，湿润的潘帕地区（61.2%）比圣地亚哥 - 德尔埃斯特罗的半干旱平原（20%）高3倍。
