Ketzis Jennifer K
Ross University School of Veterinary Medicine, Basseterre, St. Kitts and Nevis, West Indies.
Acta Trop. 2017 Jun;170:178-183. doi: 10.1016/j.actatropica.2017.03.003. Epub 2017 Mar 6.
Strongyloides stercoralis is frequently under-diagnosed due to the low sensitivity of common faecal diagnostic methods used in clinical laboratories. This leads to a belief that prevalence is low and that S. stercoralis is not an important soil-transmitted helminth (STH). S. stercoralis diagnostic methods with higher sensitivity are available but often not used. Reasons for their lack of use need to be identified and addressed in order to increase awareness of this neglected parasite.
METHODOLOGY/PRINCIPAL FINDINGS: A survey was conducted with public health (14) and private laboratories (15) within the Caribbean region to determine current diagnostic methods used and technological capabilities within the laboratories. Formal-ether concentration and direct smears were the primary methods used. Five of the laboratories used a specific method for S. stercoralis (Baermann and/or agar plate culture). A Standard Operating Procedure (SOP) for a modified Baermann tailored to be compatible with the technological capabilities of the laboratories was developed and demonstrated at ten laboratories to determine limitations to adopting a S. stercoralis specific method. The primary limitations were: cost of using two diagnostic methods for one submitted sample; lack of communication with the physician regarding the reason for the faecal analysis; general lack of awareness of S. stercoralis; and lack of awareness of differences in sensitivity of diagnostic methods.
CONCLUSIONS/SIGNIFICANCE: Changing diagnostic methods involves more than ensuring the method fits within the technological capabilities of the laboratories. Several factors that influence the method used are external to the laboratory. To improve diagnosis of any of the STHs, these external factors must be addressed. Within the laboratory, more education on the sensitivity of diagnostic methods, differences in excretion levels of diagnostic stages with low infection, and increased awareness of S. stercoralis is required.
由于临床实验室常用的粪便诊断方法灵敏度较低，粪类圆线虫常常诊断不足。这导致人们认为其感染率较低，且粪类圆线虫不是一种重要的土源性蠕虫。虽然有灵敏度更高的粪类圆线虫诊断方法，但往往未被采用。需要找出并解决这些方法未被使用的原因，以提高对这种被忽视寄生虫的认识。
方法/主要发现：对加勒比地区的14家公共卫生实验室和15家私立实验室进行了一项调查，以确定实验室目前使用的诊断方法和技术能力。正式乙醚浓缩法和直接涂片法是主要使用的方法。其中5家实验室使用了针对粪类圆线虫的特定方法（贝曼氏法和/或琼脂平板培养法）。开发了一种经过改良的、适合实验室技术能力的贝曼氏法标准操作规程（SOP），并在10家实验室进行了演示，以确定采用粪类圆线虫特定方法的局限性。主要局限性包括：对一个送检样本使用两种诊断方法的成本；与医生就粪便分析原因缺乏沟通；对粪类圆线虫普遍缺乏认识；以及对诊断方法灵敏度差异缺乏认识。
结论/意义：改变诊断方法不仅仅是要确保方法适合实验室的技术能力。影响所使用方法的几个因素来自实验室外部。为了改善任何一种土源性蠕虫的诊断，必须解决这些外部因素。在实验室内部，需要就诊断方法的灵敏度、低感染情况下诊断阶段排泄水平的差异以及提高对粪类圆线虫的认识进行更多培训。
