Field validity and feasibility of four techniques for the detection of Trichuris in simians: a model for monitoring drug efficacy in public health?

Comparison of the Kato-Katz, Wet Mount, and Formol-Ether Concentration Diagnostic Techniques for Intestinal Helminth Infections in Ethiopia

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).

Assessing resistance against macrocyclic lactones in gastro-intestinal nematodes in cattle using the faecal egg count reduction test and the controlled efficacy test

The main objective of the present study was to evaluate the accuracy of the faecal egg count reduction test (FECRT) to assess the resistance status of ivermectin (IVM)-resistant isolates of the cattle nematodes Ostertagia ostertagi and Cooperia oncophora, using the controlled efficacy test (worm counts) as a reference. The second objective was to investigate whether both IVM-resistant isolates showed side-resistance against moxidectin (MOX) under controlled conditions. Thirty male Holstein calves were experimentally infected with 25,000 L3 of an IVM-resistant O. ostertagi isolate and 25,000 L3 of an IVM-resistant C. oncophora isolate. Twenty-eight days later the calves were randomly divided into 2 treatment groups and 1 untreated control group. Animals in groups 1 and 2 received MOX (Cydectin(®) 1%, Pfizer) and IVM (Ivomec(®) 1%, Merial) respectively, by subcutaneous injection at a dose rate of 0.2mg/kg bodyweight. Faecal samples were collected 7 and 14 days after treatment and animals were necropsied 14/15 days post-treatment. Both the FECRT and the controlled efficacy test demonstrated that the O. ostertagi and C. oncophora isolates were resistant against IVM, with efficacies below 90%. The IVM-resistant O. ostertagia isolate was still susceptible to MOX treatment, as shown by over 99% reduction in egg counts and worm burden. The FECRT suggested borderline resistance against MOX in the IVM-resistant C. oncophora isolate, with egg count reductions between 97% (95% CI: 76; 100) at day 7 and 86% (95% CI: 49; 96) at day 14. However, the controlled efficacy test clearly showed MOX-resistance, with a decrease of only 31% (95% CI: -12; 57) in C. oncophora worm numbers. After MOX treatment, a significantly lower number of eggs per female C. oncophora worms was counted compared to the control group (43% reduction). Due to this reduced fecundity, the FECRT may fail to detect MOX-resistance.

The bias, accuracy and precision of faecal egg count reduction test results in cattle using McMaster, Cornell-Wisconsin and FLOTAC egg counting methods

The faecal egg count reduction test (FECRT) is the recommended method to monitor anthelmintic drug efficacy in cattle. There is a large variation in faecal egg count (FEC) methods applied to determine FECRT. However, it remains unclear whether FEC methods with an equal analytic sensitivity, but with different methodologies, result in equal FECRT results. We therefore, compared the bias, accuracy and precision of FECRT results for Cornell-Wisconsin (analytic sensitivity = 1 egg per gram faeces (EPG)), FLOTAC (analytic sensitivity = 1 EPG) and McMaster method (analytic sensitivity = 10 EPG) across four levels of egg excretion (1-49 EPG; 50-149 EPG; 150-299 EPG; 300-600 EPG). Finally, we assessed the sensitivity of the FEC methods to detect a truly reduced efficacy. To this end, two different criteria were used to define reduced efficacy based on FECR, including those described in the WAAVP guidelines (FECRT <95% and lower limit of 95%CI <90%) (Coles et al., 1992) and those proposed by El-Abdellati et al. (2010) (upper limit of 95%CI <95%). There was no significant difference in bias and accuracy of FECRT results across the three methods. FLOTAC provided the most precise FECRT results. Cornell-Wisconsin and McMaster gave similar imprecise results. FECRT were significantly underestimated when baseline FEC were low and drugs were more efficacious. For all FEC methods, precision and accuracy of the FECRT improved as egg excretion increased, this effect was greatest for McMaster and least for Cornell-Wisconsin. The sensitivity of the three methods to detect a truly reduced efficacy was high (>90%). Yet, the sensitivity of McMaster and Cornell-Wisconsin may drop when drugs only show sub-optimal efficacy. Overall, the study indicates that the precision of FECRT is affected by the methodology of FEC, and that the level of egg excretion should be considered in the final interpretation of the FECRT. However, more comprehensive studies are required to provide more insights into the complex interplay of factors inherent to study design (sample size and FEC method) and host-parasite interactions (level of egg excretion and aggregation across the host population).

Comparison of the Kato-Katz thick smear and McMaster egg counting techniques for monitoring drug efficacy against soil-transmitted helminths in schoolchildren on Pemba Island, Tanzania

The Kato-Katz thick smear technique is widely used to assess prevalence and intensity in soil-transmitted helminth (STH) control programmes, but its usefulness in monitoring anthelminthic drug efficacy needs to be validated and compared with other methods. A promising alternative is the McMaster egg counting technique. In the present study, the efficacy of single-dose albendazole against STH infections in 430 schoolchildren on Pemba Island was assessed using both the Kato-Katz and McMaster techniques. The study revealed comparable drug efficacy results for both methods and confirmed the potency of the McMaster technique as an alternative method for monitoring large-scale deworming programmes.

Novel insights in the fecal egg count reduction test for monitoring drug efficacy against soil-transmitted helminths in large-scale treatment programs

BACKGROUND

The fecal egg count reduction test (FECRT) is recommended to monitor drug efficacy against soil-transmitted helminths (STHs) in public health. However, the impact of factors inherent to study design (sample size and detection limit of the fecal egg count (FEC) method) and host-parasite interactions (mean baseline FEC and aggregation of FEC across host population) on the reliability of FECRT is poorly understood.

METHODOLOGY/PRINCIPAL FINDINGS

A simulation study was performed in which FECRT was assessed under varying conditions of the aforementioned factors. Classification trees were built to explore critical values for these factors required to obtain conclusive FECRT results. The outcome of this analysis was subsequently validated on five efficacy trials across Africa, Asia, and Latin America. Unsatisfactory (<85.0%) sensitivity and specificity results to detect reduced efficacy were found if sample sizes were small (<10) or if sample sizes were moderate (10-49) combined with highly aggregated FEC (k<0.25). FECRT remained inconclusive under any evaluated condition for drug efficacies ranging from 87.5% to 92.5% for a reduced-efficacy-threshold of 90% and from 92.5% to 97.5% for a threshold of 95%. The most discriminatory study design required 200 subjects independent of STH status (including subjects who are not excreting eggs). For this sample size, the detection limit of the FEC method and the level of aggregation of the FEC did not affect the interpretation of the FECRT. Only for a threshold of 90%, mean baseline FEC <150 eggs per gram of stool led to a reduced discriminatory power.

CONCLUSIONS/SIGNIFICANCE

This study confirms that the interpretation of FECRT is affected by a complex interplay of factors inherent to both study design and host-parasite interactions. The results also highlight that revision of the current World Health Organization guidelines to monitor drug efficacy is indicated. We, therefore, propose novel guidelines to support future monitoring programs.

Is anthelmintic resistance a concern for the control of human soil-transmitted helminths?

The major human soil-transmitted helminths (STH), Ascaris lumbricoides, hookworms (Necator americanus and Ancylostoma duodenale) and Trichuris trichiura have a marked impact on human health in many parts of the world. Current efforts to control these parasites rely predominantly on periodic mass administration of anthelmintic drugs to school age children and other at-risk groups. After many years of use of these same drugs for controlling roundworms in livestock, high levels of resistance have developed, threatening the sustainability of these livestock industries in some locations. Hence, the question arises as to whether this is likely to also occur in the human STH, thereby threatening our ability to control these parasites. This is particularly important because of the recent increase in mass control programmes, relying almost exclusively on benzimidazole anthelmintics. It will be important to ensure that resistance is detected as it emerges in order to allow the implementation of mitigation strategies, such as use of drug combinations, to ensure that the effectiveness of the few existing anthelmintic drugs is preserved. In this review we address these issues by firstly examining the efficacy of anthelmintics against the human STH, and assessing whether there are any indications to date that resistance has emerged. We then consider the factors that influence the effect of current drug-use patterns in selecting for resistant parasite populations. We describe the tools currently available for resistance monitoring (field-based coprological methods), and those under development (in vitro bioassays and molecular tests), and highlight confounding factors that need to be taken into account when interpreting such resistance-monitoring data. We then highlight means to ensure that the currently available tools are used correctly, particularly with regard to study design, and we set appropriate drug-efficacy thresholds. Finally, we make recommendations for monitoring drug efficacy in the field, as components of control programmes, in order to maximise the ability to detect drug resistance, and if it arises to change control strategy and prevent the spread of resistance.

Control of soil-transmitted helminths in sub-Saharan Africa: diagnosis, drug efficacy concerns and challenges

Soil-transmitted helminthiasis (STH) occur throughout the developing world and remain a major public health problem in the poorest communities with enormous consequences on health and development of school-aged and preschool children. The extent of the problem has long been neglected because these diseases rarely kill at a young age, due to their insidious and chronic nature. Today there exists a momentum and an unprecedented opportunity for a cost-effective control of these neglected tropical diseases. The control of these diseases has become a priority on the agenda of many governments, donors and international agencies, which provides important funding opportunities for STH control through integration and co-implementation of control interventions. In the era of preventive chemotherapy, the intensification of mass administration of anthelminthic drugs will result in epidemiological changes of STH transmission levels, with a rapid increase of light infections as far as control programmes are successful. As consequence, the current diagnostic tools may not be always appropriate and may therefore require adaptation or development of alternative assays adapted to the stage of control. This paper reviews aspects relevant to diagnosis and appropriate tools for accurate surveillance and monitoring of STH control programmes and drug efficacy. Prospects, opportunities and challenges for the control are discussed.

Comparison of the Kato-Katz and FLOTAC techniques for the diagnosis of soil-transmitted helminth infections

Decisions on individual or community treatment and evaluation of chemotherapy based control programs depend on parasitological diagnostic techniques. The aim of this study was to compare the accuracy of a single Kato-Katz thick smear and a single FLOTAC for the determination of the prevalence and intensity of soil-transmitted helminth infections. A total of 271 faecal specimens were collected from schoolchildren in Ethiopia, and microscopically examined using the Kato-Katz method (41.7 mg stool per slide) and the FLOTAC technique. The combined results from the Kato-Katz and FLOTAC methods were used as diagnostic 'gold' standard for reference in the analysis. Agreement between the two methods showed kappa values of 0.74, 0.73 and 0.28 for Ascaris lumbricoides, Trichuris trichiura and hookworm, respectively. A single FLOTAC revealed significantly more infections than a single Kato-Katz for each of the three soil-transmitted helminths (p<0.01). The sensitivities of a single Kato-Katz for diagnosis of T. trichiura, A. lumbricoides and hookworm infections were 76.6%, 67.8% and 19.6%, respectively, while the sensitivity of FLOTAC was 100% for all the three soil-transmitted helminth species. A single Kato-Katz yielded considerably higher mean faecal egg counts (FECs) (729.1, 145.2 and 60.7 eggs per gram of stool (EPG) for A. lumbricoides, T. trichiura and hookworm, respectively) compared with a single FLOTAC (142.5, 54.5 and 14.6 EPG, respectively) (p<0.05). Our study confirms that a single FLOTAC is more sensitive than a single Kato-Katz for the diagnosis of soil-transmitted helminth infections, but results in lower FECs. Further standardization and validation are still required in different epidemiological settings with varying levels of intensity of infections before recommending FLOTAC for large-scale community diagnosis.

A comparison of the sensitivity and fecal egg counts of the McMaster egg counting and Kato-Katz thick smear methods for soil-transmitted helminths

Background

The Kato-Katz thick smear (Kato-Katz) is the diagnostic method recommended for monitoring large-scale treatment programs implemented for the control of soil-transmitted helminths (STH) in public health, yet it is difficult to standardize. A promising alternative is the McMaster egg counting method (McMaster), commonly used in veterinary parasitology, but rarely so for the detection of STH in human stool.

Methodology/Principal Findings

The Kato-Katz and McMaster methods were compared for the detection of STH in 1,543 subjects resident in five countries across Africa, Asia and South America. The consistency of the performance of both methods in different trials, the validity of the fixed multiplication factor employed in the Kato-Katz method and the accuracy of these methods for estimating ‘true’ drug efficacies were assessed. The Kato-Katz method detected significantly more Ascaris lumbricoides infections (88.1% vs. 75.6%, p<0.001), whereas the difference in sensitivity between the two methods was non-significant for hookworm (78.3% vs. 72.4%) and Trichuris trichiura (82.6% vs. 80.3%). The sensitivity of the methods varied significantly across trials and magnitude of fecal egg counts (FEC). Quantitative comparison revealed a significant correlation (Rs >0.32) in FEC between both methods, and indicated no significant difference in FEC, except for A. lumbricoides, where the Kato-Katz resulted in significantly higher FEC (14,197 eggs per gram of stool (EPG) vs. 5,982 EPG). For the Kato-Katz, the fixed multiplication factor resulted in significantly higher FEC than the multiplication factor adjusted for mass of feces examined for A. lumbricoides (16,538 EPG vs. 15,396 EPG) and T. trichiura (1,490 EPG vs. 1,363 EPG), but not for hookworm. The McMaster provided more accurate efficacy results (absolute difference to ‘true’ drug efficacy: 1.7% vs. 4.5%).

Conclusions/Significance

The McMaster is an alternative method for monitoring large-scale treatment programs. It is a robust (accurate multiplication factor) and accurate (reliable efficacy results) method, which can be easily standardized.

Currently, in public health, the reduction in the number of eggs excreted in stools after drug administration is used to monitor the efficacy of drugs against parasitic worms. Yet, studies comparing diagnostic methods for the enumeration of eggs in stool are few. We compared the Kato-Katz thick smear (Kato-Katz) and McMaster egg counting (McMaster) methods, which are commonly used diagnostic methods in public and animal health, respectively, for the diagnosis and enumeration of eggs of roundworms, whipworms and hookworms in 1,536 stool samples from children in five trials across Africa, Asia and South America. The Kato-Katz method was the most sensitive for the detection of roundworms, but there was no significant difference in sensitivity between the methods for hookworms and whipworms. The sensitivity of the methods differed across the trials and magnitude of egg counts. The Kato-Katz method resulted in significantly higher egg counts, but these were subject to lack of accuracy caused by intrinsic properties of this method. McMaster provided more reliable estimates of drug efficacies. We conclude that the McMaster is an alternative method for monitoring large-scale treatment programs. It allows accurate monitoring of drug efficacy and can be easily performed under field conditions.

Monitoring drug efficacy against gastrointestinal nematodes when faecal egg counts are low: do the analytic sensitivity and the formula matter?

The faecal egg count reduction test (FECR) is the recommended technique to monitor anthelmintic drug efficacy in livestock. However, results are often inconclusive due to the low analytic sensitivity of the diagnostic technique or the conflict in results from FECR formulae. A novel experimental set-up was, therefore, used to compare the impact of analytic sensitivity and formulae on FECR results. Four McMaster techniques (analytic sensitivities 50, 33.3, 15 and 10) and a FLOTAC technique (analytic sensitivity ~ 1) were used on faecal samples of 30 calves with a FEC of less than 200 eggs per gram. True drug efficacies of 70%, 80% and 90% were experimentally mimicked by comparing FEC before and after dilution (3:10, 2:10 and 1:10, respectively). The FECR was summarized using group (FECR(1)) and individual (FECR(2)) based formulae. There was a significant increase in precision of FECR when the analytic sensitivity increased (p < 0.0001). The precision also depended on the formula used, FECR(1) (p < 0.05) resulting in more precise FECR compared to FECR(2). The accuracy of the FECR differed marginally between the two formulae (p = 0.06), FECR(1) being more accurate. In conclusion, the present study describes a novel methodology to compare techniques for the precision and the accuracy of their FECR results. The results underscored that techniques with high analytic sensitivity will improve the interpretation of FECR in animal populations where baseline FEC are low. They also point out that the precision of individual-based formulae is affected by the analytic sensitivity.

Assessment of the anthelmintic efficacy of albendazole in school children in seven countries where soil-transmitted helminths are endemic

Background

The three major soil-transmitted helminths (STH) Ascaris lumbricoides, Trichuris trichiura and Necator americanus/Ancylostoma duodenale are among the most widespread parasites worldwide. Despite the global expansion of preventive anthelmintic treatment, standard operating procedures to monitor anthelmintic drug efficacy are lacking. The objective of this study, therefore, was to define the efficacy of a single 400 milligram dose of albendazole (ALB) against these three STH using a standardized protocol.

Methodology/Principal Findings

Seven trials were undertaken among school children in Brazil, Cameroon, Cambodia, Ethiopia, India, Tanzania and Vietnam. Efficacy was assessed by the Cure Rate (CR) and the Fecal Egg Count Reduction (FECR) using the McMaster egg counting technique to determine fecal egg counts (FEC). Overall, the highest CRs were observed for A. lumbricoides (98.2%) followed by hookworms (87.8%) and T. trichiura (46.6%). There was considerable variation in the CR for the three parasites across trials (country), by age or the pre-intervention FEC (pre-treatment). The latter is probably the most important as it had a considerable effect on the CR of all three STH. Therapeutic efficacies, as reflected by the FECRs, were very high for A. lumbricoides (99.5%) and hookworms (94.8%) but significantly lower for T. trichiura (50.8%), and were affected to different extents among the 3 species by the pre-intervention FEC counts and trial (country), but not by sex or age.

Conclusions/Significance

Our findings suggest that a FECR (based on arithmetic means) of >95% for A. lumbricoides and >90% for hookworms should be the expected minimum in all future surveys, and that therapeutic efficacy below this level following a single dose of ALB should be viewed with concern in light of potential drug resistance. A standard threshold for efficacy against T. trichiura has yet to be established, as a single-dose of ALB is unlikely to be satisfactory for this parasite.

Trial Registration

ClinicalTrials.gov NCT01087099

Soil-transmitted helminths (roundworms, whipworms and hookworms) infect millions of children in (sub)tropical countries, resulting in malnutrition, growth stunting, intellectual retardation and cognitive deficits. Currently, there is a need to closely monitor anthelmintic drug efficacy and to develop standard operating procedures, as highlighted in a World Health Organization–World Bank meeting on “Monitoring of Drug Efficacy in Large Scale Treatment Programs for Human Helminthiasis” in Washington DC at the end of 2007. Therefore, we have evaluated the efficacy of a commonly used treatment against these parasitic infections in school children in Africa, Asia and South-America using a standardized protocol. In addition, different statistical approaches to analyzing the data were evaluated in order to develop standardized procedures for data analysis. The results demonstrate that the applied treatment was highly efficacious against round- and hookworms, but not against whipworms. However, there was large variation in efficacy across the different trials which warrants further attention. This study also provides new insights into the statistical analysis of efficacy data, which should be considered in future monitoring and evaluation studies of large scale anthelmintic treatment programs. Finally, our findings emphasize the need to update the World Health Organization recommended efficacy threshold for the treatment of STH.

Accuracy of the Kato-Katz, adhesive tape and FLOTAC techniques for helminth diagnosis among children in Kyrgyzstan

The purpose of this study was to assess the accuracy of three copro-microscopic techniques for helminth diagnosis: Kato-Katz, adhesive tape and FLOTAC. A total of 163 children from a peri-urban municipality near Bishkek, Kyrgyzstan, participated and submitted multiple stool samples and adhesive tapes. Ninety children supplied at least two stool samples and two adhesive tapes. Three stool samples and three adhesive tapes were available from 71 and 64 children, respectively. From each stool sample, a single Kato-Katz thick smear was prepared and examined quantitatively. Additionally, the first stool sample was subjected to the FLOTAC technique and helminth eggs were counted. Adhesive tapes were checked for the presence of Enterobius vermicularis eggs. Using pooled results as a diagnostic 'gold' standard, the prevalence of Ascaris lumbricoides, E. vermicularis, Hymenolepis nana and Dicrocoelium dendriticum were 54.4%, 13.3%, 11.1% and 11.1%, respectively. Infection intensities were low. When compared to triplicate Kato-Katz, a single FLOTAC was more sensitive for the diagnosis of A. lumbricoides (89.5% versus 39.5%) and D. dendriticum (88.9% versus 33.3%), but less sensitive for H. nana (66.7% versus 88.9%). For E. vermicularis, three adhesive tapes showed much higher sensitivity than a single FLOTAC (92.9% versus 14.3%). FLOTAC yielded significantly higher faecal egg counts than Kato-Katz for A. lumbricoides and D. dendriticum. Overall results suggest that, although FLOTAC represents a promising technique for helminth diagnosis in Kyrgyzstan, the repeated adhesive tape test remains so far the method of choice for diagnosing E. vermicularis.

Comparative cost assessment of the Kato-Katz and FLOTAC techniques for soil-transmitted helminth diagnosis in epidemiological surveys

BACKGROUND

The Kato-Katz technique is widely used for the diagnosis of soil-transmitted helminthiasis in epidemiological surveys and is believed to be an inexpensive method. The FLOTAC technique shows a higher sensitivity for the diagnosis of light-intensity soil-transmitted helminth infections but is reported to be more complex and expensive. We assessed the costs related to the collection, processing and microscopic examination of stool samples using the Kato-Katz and FLOTAC techniques in an epidemiological survey carried out in Zanzibar, Tanzania.

METHODS

We measured the time for the collection of a single stool specimen in the field, transfer to a laboratory, preparation and microscopic examination using standard protocols for the Kato-Katz and FLOTAC techniques. Salaries of health workers, life expectancy and asset costs of materials, and infrastructure costs were determined. The average cost for a single or duplicate Kato-Katz thick smears and the FLOTAC dual or double technique were calculated.

RESULTS

The average time needed to collect a stool specimen and perform a single or duplicate Kato-Katz thick smears or the FLOTAC dual or double technique was 20 min and 34 sec (20:34 min), 27:21 min, 28:14 min and 36:44 min, respectively. The total costs for a single and duplicate Kato-Katz thick smears were US$ 1.73 and US$ 2.06, respectively, and for the FLOTAC double and dual technique US$ 2.35 and US$ 2.83, respectively. Salaries impacted most on the total costs of either method.

CONCLUSIONS

The time and cost for soil-transmitted helminth diagnosis using either the Kato-Katz or FLOTAC method in epidemiological surveys are considerable. Our results can help to guide healthcare decision makers and scientists in budget planning and funding for epidemiological surveys, anthelminthic drug efficacy trials and monitoring of control interventions.

The use of a simplified faecal egg count reduction test for assessing anthelmintic efficacy on Belgian and German cattle farms

Anthelmintic resistant cattle nematodes have been reported in different regions around the world. However, in Western Europe the assessment of the problem relies largely on case reports and no prevalence data based on wide-scale surveys are available. Therefore, we performed a survey to (1) screen for reduced anthelmintic efficacy in Belgian and German cattle farms; (2) evaluate the usefulness of a simplified faecal egg count reduction test (FECRT), where efficacies are based on the mean FECs of 10 at random collected faecal samples pre- and post-treatment per farm and (3) identify possible risk factors for reduced anthelmintic efficacy. Of 88 farms included in this study, 84 farms used macrocyclic lactones (MLs). A FECR <95% was observed on 39% of these 84 farms. However, using a Markov chain Monte Carlo simulation analysis, to correct for the used McMaster FEC technique with a detection limit of 50 epg, reduced efficacy could only be confirmed in 25% of the farms (21/84). Only Cooperia spp. were found in significant numbers in the coprocultures post-treatment. Reduced efficacy was significantly associated with farm type and with a lower efficacy in beef herds compared to dairy herds. Four farms were revisited and a standardized FECRT was performed to confirm anthelmintic resistance (AR). Surprisingly, macrocyclic lactone resistance against Cooperia oncophora was only confirmed in one of four farms. In conclusion, our results show that a reduced efficacy observed in a FECRT are not only caused by AR but that the detection limit of the FEC technique used and the (in)correct administration of the anthelmintic drugs are confounding factors of major importance.

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

There is a tendency to neglect diagnostic issues in the era of 'preventive chemotherapy' in human helminthiases. However, accurate diagnosis cannot be overemphasized for adequate patient management and monitoring of community-based control programmes. Implicit is a diagnostic dilemma: the more effective interventions are in reducing helminth egg excretion, the less sensitive direct parasitological tests become. Here, experiences gained thus far with the FLOTAC technique for diagnosing common soil-transmitted helminth infections are summarized. A single FLOTAC has higher sensitivity than multiple Kato-Katz thick smears in detecting low-intensity infections. Further validation of the FLOTAC technique in different epidemiological settings is warranted, including diagnosis of intestinal schistosomiasis and food-borne trematodiases.