FLOTAC: a new sensitive technique for the diagnosis of hookworm infections in humans

Abstract

Summary Hookworms infect more than 10% of the world's population, but current diagnostic tools have drawbacks. Our objective was to compare the diagnostic performance of three methods (Kato-Katz, ether concentration and FLOTAC techniques) for hookworm diagnosis. Stool samples were obtained from 102 schoolchildren in Côte d'Ivoire. First, a duplicate 41.7 mg Kato-Katz thick smear was prepared. Next, a small portion of stool (mean weight 1.8 g) was preserved in sodium acetate-acetic acid-formalin and forwarded to a European laboratory. These samples were split in three parts, one processed by an ether concentration technique and two by the FLOTAC technique. All samples were examined by experienced technicians for hookworm eggs using light microscopy. The observed hookworm prevalences as assessed by the FLOTAC, Kato-Katz and ether concentration techniques were 65.7%, 51.0% and 28.4%, respectively. Considering the combined results as the diagnostic 'gold' standard, the FLOTAC technique had a sensitivity of 88.2% compared with 68.4% for the Kato-Katz and 38.2% for the ether concentration techniques. The Kato-Katz method resulted in a significantly higher mean number of eggs per gram of stool (155.8 EPG) compared with the FLOTAC (37.7 EPG) and ether concentration (5.7 EPG) methods. The FLOTAC method shows promise as an important new tool for individual hookworm diagnosis and for rigorous monitoring of helminth control programmes. [Clinical Trial No. ISRCTN21782274].

Reduction in Hookworm Infection after Praziquantel Treatment among Children and Young Adults in Leyte, the Philippines

“…Finally, all stool exams for worm eggs have some degree of measurement error, although for hookworm, accuracy improves with number of stool specimens. 22,29,30 We think this is less of a problem, because a large proportion of the sampled population provided three stool specimens at most follow-up visits, the number of stools provided at each time point was greater than at baseline, and we used the same procedure for collecting, preparing, and reading stool samples throughout the course of the study.…”

FLOTAC: A promising technique for detecting helminth eggs in human faeces

“…Detailed procedures of FLOTAC have been described elsewhere. 3,5,6 In brief, in the first Côte d'Ivoire and the Zanzibar study, flotation solutions no. 4 (FS4; sodium nitrate, specific gravity = 1.20) and 13 (FS13; zinc sulphate plus potassium iodomercurate, specific gravity = 1.45) were used.…”

A single FLOTAC is more sensitive than triplicate Kato–Katz for the diagnosis of low-intensity soil-transmitted helminth infections

“…Recently, it has been shown that the FLOTAC technique (a non-invasive multivalent faecal egg-count technique) 16 holds promise for the accurate diagnosis of hookworm infections. 17 As FLOTAC uses a much larger amount of stool for the detection of helminth eggs than does the Kato-Katz method (up to 1 g vs. 41.7 mg) there is a greater chance of detecting helminth eggs, especially if contained in the sample at low density.…”