Endris Mengistu, Tekeste Zinaye, Lemma Wossenseged, Kassu Afework
School of Biomedical and Laboratory Sciences, College of Medicine and Health Sciences, University of Gondar, P.O. Box 196, Gondar, Ethiopia.
ISRN Parasitol. 2012 Oct 22;2013:180439. doi: 10.5402/2013/180439. eCollection 2013.
Objective. The aim of this study was to evaluate the operational characteristics (sensitivity and negative predictive value (NPV)) of wet mount, formol-ether concentration (FEC), and Kato-Katz techniques for the determination of intestinal parasitic infections. Method. A total of 354 faecal specimens were collected from students in Northwest Ethiopia and screened with Kato-Katz, wet mount, and FEC for the presence of intestinal parasitic infection. Since a gold standard test is not available for detection of intestinal parasites, the combined results from the three methods were used as diagnostic gold standard. Result. The prevalences of intestinal parasites using the single wet mount, FEC, and Kato-Katz thick smear techniques were 38.4%, 57.1%, and 59%, respectively. Taking the combined results of three techniques as a standard test for intestinal parasitic infection, the sensitivity and negative predictive value of Kato-Katz is 81.0% (confidence interval (CI) = 0.793-0.810) and 66.2% (CI = 0.63-0.622), respectively. The FEC detected 56 negative samples that were positive by the gold standard, indicating 78.3% (CI = 0.766-0.783) and 63.2% (CI = 0.603-63) sensitivity and NPV, respectively. Furthermore, Kato-Katz detects 113 cases that were negative by a single wet mount. The κ agreement between the wet mount and Kato-Katz methods for the diagnosis of Ascaris lumbricoides and hookworm was substantial (κ = 0.61 for Ascaris lumbricoides, κ = 0.65 for hookworm).
目的。本研究旨在评估湿片法、甲醛-乙醚浓缩法（FEC）和加藤厚涂片法用于确定肠道寄生虫感染的操作特性（敏感性和阴性预测值（NPV））。方法。从埃塞俄比亚西北部的学生中总共收集了354份粪便标本，并用加藤厚涂片法、湿片法和FEC法筛查肠道寄生虫感染情况。由于尚无检测肠道寄生虫的金标准试验，因此将三种方法的联合结果用作诊断金标准。结果。使用单一湿片法、FEC法和加藤厚涂片法检测到的肠道寄生虫感染率分别为38.4%、57.1%和59%。以三种技术的联合结果作为肠道寄生虫感染的标准检测，加藤厚涂片法的敏感性和阴性预测值分别为81.0%（置信区间（CI）=0.793 - 0.810）和66.2%（CI = 0.63 - 0.622）。FEC法检测出56份经金标准检测为阳性的阴性样本，其敏感性和NPV分别为78.3%（CI = 0.766 - 0.783）和63.2%（CI = 0.603 - 63）。此外，加藤厚涂片法检测出113例单一湿片法检测为阴性的病例。湿片法和加藤厚涂片法在诊断蛔虫和钩虫方面的κ一致性较高（蛔虫的κ = 0.61，钩虫的κ = 0.65）。
