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Background Kato-Katz is a widely used method for the diagnosis of soil-transmitted helminth infection. Fecal samples cannot be preserved, and hence, should be processed on the day of collection and examined under a microscope within 60 min of slide preparation. Mini-FLOTAC is a technique that allows examining fixed fecal samples. We assessed the performance of Mini-FLOTAC using formalin-fixed stool samples compared to Kato-Katz and determined the dynamics of prevalence and intensity estimates of soil-transmitted helminth infection over a 31-day time period. Methodology The study was carried out in late 2013 on Pemba Island, Tanzania. Forty-one children were enrolled and stool samples were subjected on the day of collection to a single Kato-Katz thick smear and Mini-FLOTAC examination; 12 aliquots of stool were fixed in 5% formalin and subsequently examined by Mini-FLOTAC up to 31 days after collection. Principal Findings The combined results from Kato-Katz and Mini-FLOTAC revealed that 100% of children were positive for Trichuris trichiura, 85% for Ascaris lumbricoides, and 54% for hookworm. Kato-Katz and Mini-FLOTAC techniques found similar prevalence estimates for A. lumbricoides (85% versus 76%), T. trichiura (98% versus 100%), and hookworm (42% versus 51%). The mean eggs per gram of stool (EPG) according to Kato-Katz and Mini-FLOTAC was 12,075 and 11,679 for A. lumbricoides, 1,074 and 1,592 for T. trichiura, and 255 and 220 for hookworm, respectively. The mean EPG from day 1 to 31 of fixation was stable for A. lumbricoides and T. trichiura, but gradually declined for hookworm, starting at day 15. Conclusions/Significance The findings of our study suggest that for a qualitative diagnosis of soil-transmitted helminth infection, stool samples can be fixed in 5% formalin for at least 30 days. However, for an accurate quantitative diagnosis of hookworm, we suggest a limit of 15 days of preservation. Our results have direct implication for integrating soil-transmitted helminthiasis into transmission assessment surveys for lymphatic filariasis., Author Summary Soil-transmitted helminths are parasitic worms (hookworm, roundworm, and whipworm) that affect hundreds of millions of people. Kato-Katz is the most widely used technique for the diagnosis of soil-transmitted helminth infection. It requires the collection, processing, and microscopic examination of stool samples within the same day. In remote areas, laboratories are often far away from where stool samples are being collected, which makes it difficult to examine the samples on the same day. Mini-FLOTAC is an alternative to Kato-Katz technique that allows analysis of fixed stool samples several days after collection. We assessed the accuracy of the Mini-FLOTAC with fixed stool samples. The study was carried out in late 2013 on Pemba Island and 41 children participated. Fresh stool samples were first examined by Kato-Katz and then fixed in formalin and examined by Mini-FLOTAC (12 examinations within one month). We found that for a qualitative diagnosis (presence or absence of infection) stool samples can be fixed for 31 days. However, for an accurate quantitative diagnosis of hookworm eggs, stool samples should not be stored for more than 15 days, as egg counts decline. Our results have implications for integrating soil-transmitted helminth surveys with other neglected tropical diseases.

Background Soil-transmitted helminths and intestinal protozoa infection are widespread in developing countries, yet an accurate diagnosis is rarely performed. The aim of this study was to evaluate the recently developed mini–FLOTAC method and to compare with currently more widely used techniques for the diagnosis of intestinal parasitic infections in different settings. Methodology/Principal Findings The study was carried out in Dharamsala, Himachal Pradesh, India, and in Bukumbi, Tanzania. A total of 180 pupils from two primary schools had their stool analyzed (n = 80 in Dharamsala and n = 100 in Bukumbi) for intestinal parasitic infections with three diagnostic methods: direct fecal smear, formol-ether concentration method (FECM) and mini-FLOTAC. Overall, 72% of the pupils were positive for any intestinal parasitic infection, 24% carried dual infections and 11% three infections or more. The most frequently encountered intestinal parasites were Entamoeba coli, Entamoeba histolytica/dispar, Giardia intestinalis, hookworm, (and Schistosoma mansoni, in Tanzania). Statistically significant differences were found in the detection of parasitic infections among the three methods: mini-FLOTAC was the most sensitive method for helminth infections (90% mini-FLOTAC, 60% FECM, and 30% direct fecal smear), whereas FECM was most sensitive for intestinal protozoa infections (88% FECM, 70% direct fecal smear, and 68% mini-FLOTAC). Conclusion/Significance We present the first experiences with the mini-FLOTAC for the diagnosis of intestinal helminths and protozoa. Our results suggest that it is a valid, sensitive and potentially low-cost alternative technique that could be used in resource-limited settings — particularly for helminth diagnosis., Author Summary The mini-FLOTAC has been recently developed as a novel direct method for the diagnosis of intestinal parasitic infections. Mini-FLOTAC attempts to address the challenge of using modern technology matched with high sensitivity, affordability, and appropriateness of diagnosis in resource-limited settings where intestinal parasitic infections are widespread. We compared accuracy and feasibility of mini-FLOTAC with currently more widely used diagnostic methods, such as the direct fecal smear and the formol-ether concentration method. Our study was carried out in Dharamsala, India, and in Bukumbi, Tanzania in order to evaluate the methods under different field conditions and diverse parasitic infection profiles. Among 180 primary schoolchildren examined, 72% were positive for any intestinal parasitic infection. Mini-FLOTAC detected the highest number of helminth infections (90% sensitivity), whereas the formol-ether concentration was the most sensitive approach for intestinal protozoa infections (88% sensitivity). The logistic advantages of mini-FLOTAC are that the procedure does not require any centrifugation step or expensive equipment, it can be performed on fresh and fixed stool samples, and only requires 10–12 min of preparation before microscopic analysis. Our data suggest that mini-FLOTAC is a promising diagnostic tool for helminth diagnosis; therefore, follow-up studies in other settings are warranted.