Mini-FLOTAC and Kato-Katz: helminth eggs watching on the shore of lake Victoria

Abstract

BackgroundOne of the challenges for monitoring helminth control programmes based on preventive chemotherapy is the lack of a copro-parasitological gold–standard method that combines good sensitivity with quantitative performance, low cost, and easy-to-learn technique.The aim of our study was to evaluate and compare, the WHO recommended quantitative diagnostic technique (Kato-Katz) and the Mini-FLOTAC.MethodsMini-FLOTAC is an innovative method based on floatation of helminths eggs with two different solutions (FS2 and FS7) using a close system (Fill-FLOTAC) with 5% fixative. Kato-Katz was performed following WHO recommendation. The study was carried out in a rural part of Tanzania, close to Lake Victoria, where the laboratory facilities are fairly scarce, and the basic technique used in the local laboratory (direct smear) was taken as reference standard.Results201 children were screened for intestinal helminths and 91% of them were found to be positive. The agreement among the three techniques was calculated with k Cohen coefficient and was fairly good (k = 0.4), although the Mini-FLOTAC results were more sensitive for hookworm (98%) with FS2, and for S.mansoni (90%) with FS7 followed by Kato-Katz (91% and 60% respectively) and direct smear (30% and 10% respectively). A good agreement was found between Mini-FLOTAC and Kato-Katz (k = 0.81) with FS7 (k = 0.76) for hookworm diagnosis and a fairly good one for S.mansoni diagnosis (k = 0.5). For both infections we had a poor agreement between the two quantitative techniques and the direct smear (k<0.3). Kato-Katz diagnosed a higher number of eggs (calculated by arithmetic mean) both for hookworm (455 vs 424 EPG) and for S.mansoni (71 vs 58 EPG) compared with the Mini-FLOTAC, but the differences were not significant (p = 0.4).ConclusionsMini-FLOTAC is a promising technique, comparable and as sensitive as the Kato-Katz, which is the recommended method in intestinal helminthology for monitoring helminth control programmes. A comparative advantage of the Mini-FLOTAC is that it comprises of a closed system with preserved samples that both protects the operators and allows subsequent examination of the samples. Further studies are needed to validate the mini-FLOTAC with other quantitative techniques (McMaster) and in different settings where other soil-transmitted helminths are also endemic.

Diagnostic Accuracy and Cost-Effectiveness of Alternative Methods for Detection of Soil-Transmitted Helminths in a Post-Treatment Setting in Western Kenya

“…The observed sensitivity of each method is lower than that presented in a previous study comparing Kato-Katz and Mini-FLOTAC, which reported a sensitivity of up to 91% and 97% for detecting hookworm using Kato-Katz and Mini-FLOTAC methods respectively [16]. There are two likely reasons for the lower accuracy reported here.…”

“…The number of samples collected and diagnosed was varied within the observed maximum and minimum values. Diagnostic test sensitivity and accuracy were also varied within a distribution of observed values in this study and previous studies [16], [30], [40]. Microsoft Excel and Palisade @Risk (www.Palisade.com) were used in the analysis, and @Risk simulations of 1000 iterations were conducted for the PSA of each surveillance scenario.…”

“…The recently developed Mini-FLOTAC overcomes this constraint and includes a closed chamber for flotation and mixing, and a separate reading disc [15]. A study in Tanzania and India demonstrated that Mini-FLOTAC was more sensitive for STH diagnosis than either a direct smear or the formol-ether concentration technique, while other work has shown Mini-FLOTAC and Kato-Katz to be comparable for hookworm diagnosis in a very high prevalence setting in Tanzania [16].…”

Mini-FLOTAC, Kato-Katz and McMaster: three methods, one goal; highlights from north Argentina

“…Mini-FLOTAC has been compared with the traditionally recommended quantitative techniques, both separately [16] and, in this work, together. As shown by these results, it may be considered a valid alternative to Kato-Katz, although in this study it was only possible to test for A. lumbricoides as the prevalence of the other two major STH, T. trichiura and hookworms, was too low for a meaningful evaluation.…”

Mini-FLOTAC for counting Toxoplasma gondii oocysts from cat feces – Comparison with cell counting plates

“…Recent studies have shown that Mini-FLOTAC is more sensitive than the formol-ether concentration method and direct smear for the diagnosis of soil-transmitted helminths in humans, than the McMaster technique for the diagnosis of Eimeria in goats (Barda et al, 2013a(Barda et al, , 2013b(Barda et al, , 2013cSilva et al, 2013).…”