Faculdade de Ciências Agrárias e Veterinárias, CPPAR, Animal Health Research Center, UNESP, Via de acesso prof Paulo Donatto Castellani, 14884-900 Jaboticabal, São Paulo, Brazil.
Exp Parasitol. 2011 Jan;127(1):277-81. doi: 10.1016/j.exppara.2010.08.005. Epub 2010 Aug 22.
Two studies, of a natural infection and an experimental infection, were performed in order to study congenital transmission of Toxoplasma gondii in cattle. In the first study, 50 fetuses were harvested from gestating cows that were eutanasied at a municipal slaughterhouse in Jaboticabal, São Paulo state, Brazil. In the second study, 11 gestating cows were divided into four groups for inoculation with T. gondii: GI consisted of three cows inoculated with 1.0 × 10(5) oocysts during their first trimester of gestation; GII consisted of three cows inoculated with 1.0 × 10(5) oocysts during their second trimester of gestation; GIII consisted of three cows inoculated with 1.0 × 10(5) oocysts during their last trimester of gestation; and GIV consisted of two control cows, one during its first and the other during its second trimester of gestation. In both studies, the presence of T. gondii was confirmed both indirectly by immunofluorescence assay (IFAT). In the natural infection experiment, 18% (9/50) of the gestating cows were confirmed to have specific antibodies (IFAT--1:64) against T. gondii. The bioassay was able to diagnose the presence of T. gondii in the tissue samples from three calves. In the second experiment, the nine cows from groups I, II and III presented with specific antibodies (IFAT) against T. gondii. In contrast, T. gondii could not be detected by IFAT, histopathological examination or the bioassay in any of the nine calves born to cows experimentally infected with T. gondii oocysts. Based on the results from both studies, we conclude that congenital infection of T. gondii in cattle, while infrequent, does occur naturally. The pathogenicity of the strain of T. gondii may influence the likelihood of this route of transmission.
为了研究弓形虫在牛中的先天性传播，进行了两项研究，一项是自然感染研究，另一项是实验感染研究。在第一项研究中，从巴西圣保罗州雅博蒂巴市的一家市立屠宰场安乐死的妊娠母牛中收获了 50 头胎牛。在第二项研究中，将 11 头妊娠母牛分为四组进行弓形虫接种：GI 组由三头母牛组成，在妊娠的第一 trimester 接种 1.0×10(5)个卵囊；GII 组由三头母牛组成，在妊娠的第二 trimester 接种 1.0×10(5)个卵囊；GIII 组由三头母牛组成，在妊娠的最后 trimester 接种 1.0×10(5)个卵囊；GIV 组由两头母牛组成，一头在妊娠第一 trimester，另一头在妊娠第二 trimester。在这两项研究中，均通过间接免疫荧光检测（IFA）证实了弓形虫的存在。在自然感染实验中，18%（9/50）的妊娠母牛被证实具有针对弓形虫的特异性抗体（IFA--1:64）。生物检测能够在三只小牛的组织样本中诊断出弓形虫的存在。在第二项实验中，I、II 和 III 组的九头牛均出现了针对弓形虫的特异性抗体（IFA）。相比之下，在通过实验感染弓形虫卵囊的牛所生的九只小牛中，IFA、组织病理学检查或生物检测均未检测到弓形虫。基于这两项研究的结果，我们得出结论，弓形虫在牛中的先天性感染虽然不常见，但确实会自然发生。弓形虫株的致病性可能会影响这种传播途径的可能性。
