Department of Zoonotic Diseases, Veterinary Research Division, National Research Centre, El-Tahrir Street, Dokki, Post Box 12622, Giza, Egypt.
Zoology Department, Faculty of Science, Cairo University, Giza, Egypt.
Acta Parasitol. 2022 Mar;67(1):437-445. doi: 10.1007/s11686-021-00483-4. Epub 2021 Oct 22.
This study investigated the prevalence and molecular detection of Cryptosporidium spp. in catfish (Clarias gariepinus).
A total of 300 Carias gariepinus fish were collected from two freshwater sources: the Nile River (180) and drainage canals (120). The stomach and intestine epithelium of each individual fish sample were screened by modified Ziehl-Neelsen (mZN) staining technique for the detection of Cryptosporidium oocysts followed by the serological survey for detection of Cryptosporidium antibodies using Enzyme-Linked Immunosorbent Assay (ELISA) and molecular characterization using complemented DNA polymerase chain reaction (cPCR).
ELISA showed higher prevalence of 69.3% than that prevalence obtained by mZN, 64% for the total examined Clarias gariepinus fish. Also, higher prevalence of Cryptosporidium infection 65.5% and 75.8% obtained by ELISA than 61.1% and 68.3% by mZN, in both fish groups from Nile River and Drainage canal, respectively. PCR analysis revealed the expected positive bands at 1056 bp. DNA sequencing and phylogenetic analysis proved that the positive-PCR Cryptosporidium isolate identified in the present study was Cryptosporidium molnari.
Freshwater fishes (Clarias gariepinus) are subjected to a high infection rate with Cryptosporidium spp.; the drainage canals obtained fishes showed higher prevalence than that collected from Nile River which indicates an important public health problem and a potential risk of drainage canals in Egypt. ELISA showed higher prevalence of cryptosporidiosis than mZN, for the total examined Clarias gariepinus fish and phylogenetic analyses confirmed this protozoal organism to be a novel species of Cryptosporidium molnari.
本研究调查了鲶鱼（Clarias gariepinus）中隐孢子虫属的流行情况和分子检测。
从尼罗河（180 份）和排水渠（120 份）两个淡水来源采集了 300 份鲶鱼样本。采用改良的齐尔-尼尔森（mZN）染色技术对每个个体鱼样的胃和肠上皮进行筛查，以检测隐孢子虫卵囊，然后采用酶联免疫吸附试验（ELISA）检测隐孢子虫抗体，并用补充的 DNA 聚合酶链反应（cPCR）进行分子特征分析。
ELISA 显示的总阳性率为 69.3%，高于 mZN 检测的 64%，以及尼罗河流域和排水渠所有鲶鱼样本的 64%。此外，ELISA 检测到的隐孢子虫感染率高于 mZN，尼罗河流域和排水渠鲶鱼样本分别为 65.5%和 75.8%，而 mZN 检测到的感染率分别为 61.1%和 68.3%。PCR 分析显示预期的 1056bp 阳性条带。DNA 测序和系统发育分析证实，本研究中从阳性-PCR 隐孢子虫分离株鉴定为莫氏隐孢子虫。
淡水鱼类（Clarias gariepinus）受到隐孢子虫属的高度感染；从排水渠采集的鱼类比从尼罗河采集的鱼类显示出更高的感染率，这表明排水渠存在重要的公共卫生问题，也是埃及的一个潜在风险。ELISA 检测到的隐孢子虫病阳性率高于 mZN，对所有检测的鲶鱼样本均如此，系统发育分析证实这种原生动物是一种新型的莫氏隐孢子虫。
