Parasit Vectors. 2013 Sep 17;6:266. doi: 10.1186/1756-3305-6-266.
The protozoan Toxoplasma gondii is the causative agent of toxoplasmosis, with complications varying from mental disease to death. While human infection can occur via ingestion of tissue cysts from infected meat, most human infection comes from oocysts. Cats are the only definitive host, and thus shedding of oocysts by cats provides the ultimate source of toxoplasmosis.
While most studies in the area use seroprevalence to monitor Toxoplasma incidence in cat populations, this provides only a history of infection. This study used PCR detection of oocysts from cat feces to more accurately estimate the numbers of cats producing oocysts and thus posing an active health risk. DNA sequencing was use to confirm the identity of the PCR products.
Of the 49 cats tested, 9 yielded PCR products of the expected size. Six of the nine were determined by sequence analysis to be false positives, while three products were true positives. Overall, 6% of cats examined were found to be actively shedding oocysts.
The incidence of oocyst shedding in the cat population studied was significantly higher than expected and higher than found in most cat populations world-wide. Of equal importance, the primers tested were shown to produce PCR products of multiple sizes and non-target products of expected size. We detected false positives at a higher rate than true positives, emphasizing the need for confirmatory analysis. Further research may produce better protocols for Toxoplasma detection from cat fecal samples.
原生动物刚地弓形虫是弓形体病的病原体，其并发症从精神疾病到死亡不等。虽然人类感染可以通过摄入感染肉组织中的包囊来发生，但大多数人类感染来自卵囊。猫是唯一的终宿主，因此猫排出的卵囊是弓形体病的最终来源。
虽然该领域的大多数研究都使用血清流行率来监测猫群中的弓形体病发病率，但这只能提供感染的历史记录。本研究使用从猫粪便中检测卵囊的 PCR 来更准确地估计产生卵囊的猫的数量，从而构成主动健康风险。使用 DNA 测序来确认 PCR 产物的身份。
在 49 只受检猫中，有 9 只产生了预期大小的 PCR 产物。通过序列分析，其中 6 个被确定为假阳性，而 3 个为真阳性。总的来说，受检猫中有 6%被发现正在主动排出卵囊。
在所研究的猫群中，卵囊排出的发生率明显高于预期，高于全球大多数猫群。同样重要的是，测试的引物产生了多种大小的 PCR 产物和预期大小的非靶产物。我们检测到假阳性的比例高于真阳性，这强调了需要进行确认性分析。进一步的研究可能会为从猫粪便样本中检测弓形体病产生更好的方案。
