Effects of hypertonic solutions on two species of human intestinal parasites during fecal examination.

Aim: Ova and parasite examination by flotation requires hypertonic solutions, which can damage the egg and cyst membranes, leading to false negatives. The authors investigated the harmful effects of ZnSO4 and C12H22O11 solutions on the ova and parasite examination. Materials & methods: The authors processed samples using the Three Fecal Test technique. Aliquots were floated in different pH levels, temperatures and solution densities. Results: Densities above 1.12 g/ml led structures to collapse after 6-10 min. pH neutralization of the ZnSO4 solution did not prevent the parasites from changing. Conclusion: All structures were altered when standard methods were performed. To delay collapse, the parasite floating under 5 °C is highly desirable.

Fecal exams require solutions that can damage the intestinal parasite's shape. This is bad for diagnosis. The authors investigated the harmful effects of these solutions on fecal exams. The authors processed samples using a technique called the Three Fecal Test. Fecal samples were floated in different conditions, including neutral and acidic solutions, high and low temperatures and varying densities of chemical solutions. Densities above 1.12 g/ml altered the structures of parasites. Neutral solutions did not prevent the structures from changing. The structures of all parasites were altered when the usual techniques were performed. Thus, the techniques for diagnosing intestinal parasites in feces must be improved. Temperatures under 5 °C are the best for preventing the destruction of parasite membranes.

The effect of ivermectin alone and in combination with cobicistat or elacridar in experimental Schistosoma mansoni infection in mice.

Schistosoma mansoni is less susceptible to the antiparasitic drug ivermectin than other helminths. By inhibiting the P-glycoprotein or cytochrome P450 3A in mice host or parasites in a murine model, we aimed at increasing the sensitivity of S. mansoni to the drug and thus preventing infection. We assigned 124 BALB/c mice to no treatment, treatment with ivermectin only or a combination of ivermectin with either cobicistat or elacridar once daily for three days before infecting them with 150 S. mansoni cercariae each. The assignment was done by batches without an explicit randomization code. Toxicity was monitored. At eight weeks post-infection, mice were euthanized. We determined number of eggs in intestine and liver, adult worms in portal and mesenteric veins. Disease was assessed by counting granulomas/cm2 of liver and studying organ weight indices and total weight. IgG levels in serum were also considered. No difference between groups treated with ivermectin only or in combination with cobicistat or elacridar compared with untreated, infected controls. Most mice treated with ivermectin and elacridar suffered severe neurological toxicity. In conclusion, systemic treatment with ivermectin, even in the presence of pharmacological inhibition of P-glycoprotein or cytochrome P450 3A, did not result in effective prophylaxis for S. mansoni infection in an experimental murine model.

The effect of analyst training on fecal egg counting variability.

Fecal egg counts (FECs) are essential for veterinary parasite control programs. Recent advances led to the creation of an automated FEC system that performs with increased precision and reduces the need for training of analysts. However, the variability contributed by analysts has not been quantified for FEC methods, nor has the impact of training on analyst performance been quantified. In this study, three untrained analysts performed FECs on the same slides using the modified McMaster (MM), modified Wisconsin (MW), and the automated system with two different algorithms: particle shape analysis (PSA) and machine learning (ML). Samples were screened and separated into negative (no strongylid eggs seen), 1-200 eggs per gram of feces (EPG), 201-500 EPG, 501-1000 EPG, and 1001+ EPG levels, and ten repeated counts were performed for each level and method. Analysts were then formally trained and repeated the study protocol. Between analyst variability (BV), analyst precision (AP), and the proportion of variance contributed by analysts were calculated. Total BV was significantly lower for MM post-training (p = 0.0105). Additionally, AP variability and analyst variance both tended to decrease for the manual MM and MW methods. Overall, MM had the lowest BV both pre- and post-training, although PSA and ML were minimally affected by analyst training. This research illustrates not only how the automated methods could be useful when formal training is unavailable but also how impactful formal training is for traditional manual FEC methods.

Further evaluation and validation of the VETSCAN IMAGYST: in-clinic feline and canine fecal parasite detection system integrated with a deep learning algorithm.

BACKGROUND: Fecal examinations in pet cats and dogs are key components of routine veterinary practice; however, their accuracy is influenced by diagnostic methodologies and the experience level of personnel performing the tests. The VETSCAN IMAGYST system was developed to provide simpler and easier fecal examinations which are less influenced by examiners' skills. This system consists of three components: a sample preparation device, an automated microscope scanner, and analysis software. The objectives of this study were to qualitatively evaluate the performance of the VETSCAN IMAGYST system on feline parasites (Ancylostoma and Toxocara cati) and protozoan parasites (Cystoisospora and Giardia) and to assess and compare the performance of the VETSCAN IMAGYST centrifugal flotation method to reference centrifugal and passive flotation methods. METHODS: To evaluate the diagnostic performance of the scanning and algorithmic components of the VETSCAN IMAGYST system, fecal slides were prepared by the VETSCAN IMAGYST centrifugal flotation technique with pre-screened fecal samples collected from dogs and cats and examined by both an algorithm and parasitologists. To assess the performance of the VETSCAN IMAGYST centrifugal flotation technique, diagnostic sensitivity and specificity were calculated and compared to those of conventional flotation techniques. RESULTS: The performance of the VETSCAN IMAGYST algorithm closely correlated with evaluations by parasitologists, with sensitivity of 75.8-100% and specificity of 93.1-100% across the targeted parasites. For samples with 50 eggs or less per slide, Lin's concordance correlation coefficients ranged from 0.70 to 0.95 across the targeted parasites. The results of the VETSCAN IMAGYST centrifugal flotation method correlated well with those of the conventional centrifugal flotation method across the targeted parasites: sensitivity of 65.7-100% and specificity of 97.6-100%. Similar results were observed for the conventional passive flotation method compared to the conventional centrifugal flotation method: sensitivity of 56.4-91.7% and specificity of 99.4-100%. CONCLUSIONS: The VETSCAN IMAGYST scanning and algorithmic systems with the VETSCAN IMAGYST fecal preparation technique demonstrated a similar qualitative performance to the parasitologists' examinations with conventional fecal flotation techniques. Given the deep learning nature of the VETSCAN IMAGYST system, its performance is expected to improve over time, enabling it to be utilized in veterinary clinics to perform fecal examinations accurately and efficiently.

Criteria for identification of Schistosoma mansoni eggs in faecal sediments prepared with the Helmintex method and stained by ninhydrin

Helmintex is a sensitive method used for detecting Schistosoma mansoni eggs. Here, we describe the observed frequency of six proposed criteria associated with the identification of S. mansoni eggs prepared with the Helmintex method and stained with ninhydrin. The efficacy of these criteria in classifying S. mansoni eggs when applied in various combinations was also examined. Nine observers registered the presence or absence of 6 different criteria in 100 eggs using a microscope at 100x magnification. Ninhydrin purple, which was frequently observed, was the criterion associated with the lowest inter-observer variability. At least three criteria were associated with a significantly better performance in egg identification. In conclusion, ninhydrin staining and a combination of criteria are recommended for microscope examination of faecal sediments.

Epiisopilosine alkaloid has activity against Schistosoma mansoni in mice without acute toxicity.

Schistosomiasis is a disease caused by parasites of the genus Schistosoma, currently affecting more than 200 million people. Among the various species of this parasite that infect humans, S. mansoni is the most common. Pharmacological treatment is limited to the use of a single drug, praziquantel (PZQ), despite reports of parasite resistance and low efficacy. It is therefore necessary to investigate new potential schistosomicidal compounds. In this study, we tested the efficacy of epiisopilosine (EPIIS) in a murine model of schistosomiasis. A single dose of EPIIS (100 or 400 mg/kg) administered orally to mice infected with adult S. mansoni resulted in reduced worm burden and egg production. The treatment with the lower dose of EPIIS (100 mg/kg) significantly reduced total worm burden by 60.61% (P < 0.001), as well as decreasing hepatosplenomegaly and egg excretion. Scanning electron microscopy revealed morphological changes in the worm tegument after treatment. Despite good activity of EPIIS in adult S. mansoni, oral treatment with single dose of EPIIS 100 mg/kg had only moderate effects in mice infected with juvenile S. mansoni. In addition, we performed cytotoxicity and toxicological studies with EPIIS and found no in vitro cytotoxicity (in HaCaT, and NIH-3T3 cells) at a concentration of 512 µg/mL. We also performed in silico analysis of toxicological properties and showed that EPIIS had low predicted toxicity. To confirm this, we investigated systemic acute toxicity in vivo by orally administering a 2000 mg/kg dose to Swiss mice. Treated mice showed no significant changes in hematological, biochemical, or histological parameters compared to non-treated animals. Epiisopilosine showed potential as a schistosomicidal drug: it did not cause acute toxicity and it displayed an acceptable safety profile in the animal model.

Evaluation of Parasite Egg and Cyst Recovery Using Devices Designed for Centrifugal or Stationary Flotation.

Two new devices (OT, ST), were recently introduced for the recovery of parasite eggs and cysts for microscopic examination. These devices, two stationary flotation devices, and a standard double-centrifugal sugar-flotation were compared using common flotation solutions and methods recommended by the manufacturers for the recovery of hookworm, ascaridoid, and whipworm eggs from companion animal fecal samples. Additionally, the recovery of Giardia cysts in the OT device using a zinc sulfate versus sodium nitrate solution was evaluated. Double-centrifugal sugar-flotation (1.30 specific gravity) was the most sensitive method for the recovery of the nematode eggs from feces of companion animals. Overall, centrifugation increased the recovery of eggs as compared with standing flotation methods, with the ST performing equivalently to the OT. Although these more recently introduced tests have good sensitivities for the nematodes tested, egg recovery was routinely markedly less than that achieved by standard double-centrifugal sugar-flotation, and false-negatives did occur. Still, the OT and ST generally have increased recoveries over the two standing flotation devices, and are significantly better than these for the recovery of ascaridoid and whipworm eggs from dog and cat samples. Zinc sulfate (1.18 specific gravity) is recommended for the recovery of Giardia cysts when using the OT device.

A Comparative Study of Four Methods for the Detection of Nematode Eggs and Large Protozoan Cysts in Mandrill Faecal Material.

Coproscopical methods like sedimentation and flotation techniques are widely used in the field for studying simian gastrointestinal parasites. Four parasites of known zoonotic potential were studied in a free-ranging, non-provisioned population of mandrills (Mandrillus sphinx): 2 nematodes (Necatoramericanus/Oesophagostomum sp. complex and Strongyloides sp.) and 2 protozoan species (Balantidium coli and Entamoeba coli). Different coproscopical techniques are available but they are rarely compared to evaluate their efficiency to retrieve parasites. In this study 4 different field-friendly methods were compared. A sedimentation method and 3 different McMaster methods (using sugar, salt, and zinc sulphate solutions) were performed on 47 faecal samples collected from different individuals of both sexes and all ages. First, we show that McMaster flotation methods are appropriate to detect and thus quantify large protozoan cysts. Second, zinc sulphate McMaster flotation allows the retrieval of a higher number of parasite taxa compared to the other 3 methods. This method further shows the highest probability to detect each of the studied parasite taxa. Altogether our results show that zinc sulphate McMaster flotation appears to be the best technique to use when studying nematodes and large protozoa.

[Concordance between the zinc sulphate flotation and centrifugal sedimentation methods for the diagnosis of intestinal parasites].

INTRODUCTION: The diagnosis of intestinal parasitic infections depends on the parasite load, the specific gravity density of the parasite eggs, oocysts or cysts, and the density and viscosity of flotation or sedimentation medium where faeces are processed. OBJECTIVE: To evaluate the concordance between zinc sulphate flotation and centrifugal sedimentation in the recovery of parasites in faecal samples of children. MATERIALS AND METHODS: Faecal samples of 330 children from day care centers were evaluated by zinc sulphate flotation and centrifugal sedimentation techniques. The frequencies of detection of parasites by each method were determined and the agreement between the diagnostic techniques was evaluated using the kappa index, with 95% confidence intervals. RESULTS: The faecal flotation in zinc sulphate diagnosed significantly more cases of Trichuris trichiura infection when compared to centrifugal sedimentation (39/330; 11.8% vs. 13/330; 3.9%, p<0.001), with low diagnostic concordance between methods (kappa=0.264; 95% CI: 0.102-0.427). Moreover, all positive samples for Enterobius vermicularis eggs (n=5) and Strongyloides stercoralis larvae (n=3) were diagnosed only by zinc sulphate. No statistical differences were observed between methods for protozoa identification. CONCLUSIONS: The results showed that centrifugal flotation in zinc sulphate solution was significantly more likely to detect light helminths eggs such as those of T. trichiura and E. vermicularis in faeces than the centrifugal sedimentation process.

Concordance between the zinc sulphate flotation and centrifugal sedimentation methods for the diagnosis of intestinal parasites / Concordancia entre los métodos de flotación con sulfato de zinc y sedimentación centrífuga para el diagnóstico de parásitos intestinales

Resumen Introduction: The diagnosis of intestinal parasitic infections depends on the parasite load, the specific gravity density of the parasite eggs, oocysts or cysts, and the density and viscosity of flotation or sedimentation medium where faeces are processed. Objective: To evaluate the concordance between zinc sulphate flotation and centrifugal sedimentation in the recovery of parasites in faecal samples of children. Materials and methods: Faecal samples of 330 children from day care centers were evaluated by zinc sulphate flotation and centrifugal sedimentation techniques. The frequencies of detection of parasites by each method were determined and the agreement between the diagnostic techniques was evaluated using the kappa index, with 95% confidence intervals. Results: The faecal flotation in zinc sulphate diagnosed significantly more cases of Trichuris trichiura infection when compared to centrifugal sedimentation (39/330; 11.8% vs. 13/330; 3.9%, p<0.001), with low diagnostic concordance between methods (kappa=0.264; 95% CI: 0.102-0.427). Moreover, all positive samples for Enterobius vermicularis eggs (n=5) and Strongyloides stercoralis larvae (n=3) were diagnosed only by zinc sulphate. No statistical differences were observed between methods for protozoa identification. Conclusions: The results showed that centrifugal flotation in zinc sulphate solution was significantly more likely to detect light helminths eggs such as those of T. trichiura and E. vermicularis in faeces than the centrifugal sedimentation process.

Abstract Introducción. El diagnóstico de infecciones parasitarias intestinales depende de la carga de parásitos, la densidad de la gravedad específica de los huevos, ooquistes o quistes de parásitos, y de la densidad y viscosidad de los reactivos de flotación o sedimentación usados para procesar las heces. Objetivo. Evaluar la concordancia entre el método de flotación de sulfato de zinc y la sedimentación por centrifugación en la recuperación de parásitos en muestras fecales de niños. Materiales y métodos. Se evaluaron las muestras fecales de 330 niños de guarderías mediante las técnicas de flotación con sulfato de zinc y de sedimentación por centrifugación. Se determinó la frecuencia de detección de parásitos con cada método y se evaluó la concordancia entre las técnicas de diagnóstico mediante el índice kappa, con intervalos de confianza del 95 %. Resultados. Mediante la flotación fecal con sulfato de zinc, se diagnosticó un número significativamente mayor de casos de infección por Trichuris trichiura que con la sedimentación por centrifugación (39/330; 11,8 % Vs. 13/330; 3,9 %) (p<0,001), con poco acuerdo entre los métodos (kappa=0,264; IC95% 0,102-0,427). Además, todas las muestras positivas para huevos de Enterobius vermicularis (n=5) y larvas de Strongyloides stercoralis (n=3) se diagnosticaron solamente por sulfato de zinc. No se observaron diferencias estadísticamente significativas entre los métodos para la identificación de protozoos. Conclusiones. La flotación centrífuga en una solución de sulfato de zinc presentó una probabilidad significativamente mayor de detectar los huevos livianos de helmintos como T. trichiura y E. vermicularis en heces, que el proceso de sedimentación por centrifugación.

Estudio de la presencia de huevos de Toxocara sp. en suelos de áreas públicas de la ciudad de Chillán, Chile / Study of Toxocara sp. eggs in soils of public areas of the city of Chillán, Chile

Introduction: Squares and public areas are mentioned frequently as source of infections by Toxocara sp. for people. There is no study of the presence of Toxocara sp. eggs in soils of the city of Chillán, Chile. Aims: To assess the presence of toxocara eggs in the soils of public areas of Chillán. Material and Methods: 43 public areas were studied in January of 2014. Samples were processed by sedimentation-flotation method. In addition, two positive control assays were performed: one with feces contaminated with Toxocara eggs mixed with soil; and the other leaving the feces on the soil and then analyzing this soil. Results: No Toxocara eggs were detected in public areas, but they were found in both positive control assays. Discussion: Several factors, including seasonality (summer) and the frequency of the cleaning of the areas, may explain this result, which cannot be interpreted necessarily as a lack of risk, but instead as a low risk, if it exists, given the possibility that the load may be low enough as to be undetectable.

Introducción: Las áreas públicas se mencionan frecuentemente como fuente de infección por Toxocara sp. para la población. En la ciudad de Chillán no se han realizado estudios de la presencia de huevos de Toxocara sp. en suelos de áreas públicas. Objetivos: Evaluar la presencia de huevos de Toxocara en suelos de áreas públicas de la ciudad de Chillán. Material y Método: Se evaluaron 43 áreas públicas en enero de 2014, analizándose sus suelos mediante el método de sedimentación-flotación. Además se realizaron dos ensayos como controles positivos, uno con una mezcla de heces positivas a huevos de Toxocara y suelo, luego se analizó la mezcla, y el otro dejando heces positivas sobre el suelo, y luego analizando sólo el suelo. Resultados: No se detectaron huevos de Toxocara en las muestras de áreas públicas, pero sí se encontraron en ambos controles positivos. Discusión: Diversos factores, incluyendo la estacionalidad (verano) y la frecuencia de la limpieza en las áreas, pueden explicar este resultado, el que no debe ser interpretado necesariamente como una carencia de riesgo, sino más bien como un riesgo que de existir es escaso, dada la posibilidad que la carga sea lo suficientemente baja para no ser detectada.

Pathological and parasitological aspects of the peacock (Pavo cristatus) infection by Tanaisia (Paratanaisia) bragai / Aspectos patológicos e parasitológicos da infecção por Tanaisia (Paratanaisia) bragai em pavões (Pavo cristatus)

Trematodes belonging to the family Eucotylidae, including Tanaisia (Paratanaisia)bragai Santos, 1934are parasites of the kidney and ureter that affect several species of domestic and wild birds. Tanaisia bragai is considered a low pathogenic parasite, but high worm burdens may determine clinical complications, including signs of apathy, weight loss, diarrhea and death...

Os trematódeos da família Eucotylidae, incluindo Tanaisia (Paratanaisia)bragai Santos, 1934, são parasitos de rins e ureteres de várias espécies de aves domésticas e silvestres. Tanaisia bragai é considerada uma espécie pouco patogênica, mas que pode determinar complicações clínicas como apatia, perda de peso, diarreia e morte, quando em cargas parasitárias elevadas...

Echinococcus multilocularis in North America: the great unknown.

Over the last decade, studies have begun to shed light on the distribution and genetic characterization of Echinococcus multilocularis, the causative agent of alveolar echinococcosis (AE), in North America. Recent findings indicate that the parasite is likely expanding its range in the central region of the United States and Canada and that invasions of European strains might have occurred. In our review, we present the available data on E. multilocularis infections in wild and domestic animals and humans in North America and emphasize the lack of knowledge on the distribution of the parasite in wild and domestic hosts. Furthermore, we stress the need to better understand the complexity of host communities and their roles in shaping the transmission and distribution of the parasite. We hypothesize that a lack of knowledge about AE by North American physicians might result in the misdiagnosis of cases and an underestimation of disease incidence. The endemic presence of the parasite in urban areas and a recent human case in Alberta, Canada, suggest that the scientific community may need to reconsider the local public health risks, re-assess past cases that might have been overlooked and increase surveillance efforts to identify new cases of human AE.

Laboratory assessment of sensitive molecular tools for detection of low levels of Echinococcus multilocularis-eggs in fox (Vulpes vulpes) faeces.

BACKGROUND: In endemic areas with very low infection prevalence, the frequency and intensity of Echinococcus multilocularis can be extremely low. This necessitates efficient, specific and sensitive molecular tools. We wanted to compare the existing molecular tools, used in the Norwegian national surveillance programme, and compare these with new techniques for detection of this zoonotic pathogen in fox faeces. Here we present the results of screening samples containing a known level of E. multilocularis eggs with two highly sensitive DNA isolation and extraction methods combined with one conventional PCR and three real-time PCR methods for detection. METHODS: We performed a comparison of two extraction protocols; one based on sieving of faecal material and one using targeted DNA sampling. Four methods of molecular detection were tested on E. multilocularis-egg spiked fox faeces. RESULTS: There were significant differences between the multiplex PCR/egg sieving DNA extraction methods compared to the new DNA fishing method and the three real-time PCR assays. Results also indicate that replicates of the PCR-reactions improve detection sensitivity when egg numbers are low. CONCLUSIONS: The results indicate that the use of real-time PCR combined with targeted DNA extraction, improves the sensitivity of E. multilocularis detection in faecal samples containing low numbers of E. multilocularis eggs. Results also indicate the importance of replicates of the PCR-reactions when pathogen levels are low.

Re-evaluation of the formalin-ether sedimentation method for the improvement of parasite egg recovery efficiency.

The formalin-ether sedimentation (FES) method is considered as reliable method of fecal examination for the detection of parasites. In this study, we re-evaluated several aspects of FES such as (i) pretreatment of feces; (ii) filtration of fecal suspensions; (iii) test-tube material and (iv) substitution of ether by other organic solvents as to see an improvement in parasite egg recovery. The egg count was represented by the number of ova detected per 100 µg of sediment. Pre-treatment of feces with formalin (pH 7) increased egg detection rate remarkably compared with original FES method. Use of three layers of gauze dramatically reduced the sediment in the final product, and led to an increase in the number of ova detected. Use of polypropylene test tubes instead of glass test tubes also increased the number of egg detection. None of the organic solvents used to replace the ether produced better results. Based on these findings, we proposed a modified FES procedure. Further, we also compared the parasite positive rate and the number of ova recovered by using original FES and the modified FES procedures by examining 112 fecal samples collected from school children of parasite endemic area in Nepal. Feces collected from Nepal had many parasite ova, and these fecal samples barely displayed false-negative results even by method with low sensitivity. When the mean number of Hemenolepis nana, hookworm, T. trichiura, and A. lumbricoides ova recovered by original FES and the modified FES methods was compared, the values obtained by modified FES were superior (higher). This result suggested that the modified FES is effective and better for the recovery of parasite ova in areas of low-intensity parasitic infection.

A rapid diagnostic test for schistosomiasis mansoni

This article presents an improvement to the Kato-Katz (KK) method, making it faster and more efficient for the visualisation of fertile eggs in stool samples. This modified KK method uses sodium acetate formalin as a fixative and reveals the intensity of infection in less than 1 h, reducing the diagnostic time without increasing the cost. This modified method may contribute to future epidemiological studies in both hospitals and the field due to its rapid and precise diagnostic, which allow for immediate treatment.

A conventional polymerase chain reaction-based method for the diagnosis of human schistosomiasis in stool samples from individuals in a low-endemicity area

The aim of this study was to evaluate the efficacy of a polymerase chain reaction (PCR)-based method to detect Schistosoma mansoni DNA in stool samples from individuals living in a low-endemicity area in Brazil. Of the 125 initial stool samples, 80 were ELISA reactive and eggs were identified in 19 of the samples by parasitological examination. For the PCR evaluations, 56 stool samples were selected and divided into five groups. Groups I-IV were scored negative for S. mansoni eggs by parasitological examination. Groups I and II were ELISA reactive, whereas Groups III and IV were ELISA nonreactive. Groups II and III were positive for other intestinal parasites. PCR testing scored eight samples as positive from these four groups. Group V represented the S. mansoni -positive group and it included ELISA-reactive samples that were scored positive for S. mansoni by one or more parasitological examinations (6/19 were positive by Kato-Katz method, 9/17 by saline gradient and 10/13 by Helmintex®). PCR scored 13 of these 19 samples as positive for S. mansoni . We conclude that while none of these methods yielded 100% sensitivity, a combination of techniques should be effective for improving the detection of S. mansoni infection in low-endemicity areas.

[Evaluation of the Kato-Katz technique for monitoring Schistosoma mansoni infestation in endemic areas]. / Évaluation de la technique de Kato-Katz pour la surveillance des infestations à Schistosoma mansoni en zone d'endémie.

The Kato-Katz technique has become the gold standard for all studies on intestinal schistosomiasis. Though repeatability and reproducibility can be disappointing and the sensitivity is low, it remains easy, inexpensive, and fast and as such, is perfectly suited for epidemiological surveys or to monitor the effectiveness of mass treatment. For optimal interpretation of the Kato-Katz results in a recent study of three endemic villages in the Senegal River basin, a study of the measurement uncertainties of this analysis was conducted according to Cofrac and ISO 15189 guidelines. Repeat examinations of stool smears from the same individual, taken a few days apart, can significantly increase the sensitivity of the Kato-Katz test, which allows its use as a technique in clinical biology.

Evaluation of a novel rapid diagnostic test for Schistosoma haematobium based on the detection of human immunoglobulins bound to filtered Schistosoma haematobium eggs.

OBJECTIVES: To determine whether the detection of human IgG bound to Schistosoma haematobium eggs from filtered urine could be used as a rapid diagnostic test (RDT-Sh). METHODS: We filtered 160 urine samples from children in the Kwale District of Kenya to isolate S. haematobium eggs and used anti-human IgG antibody conjugated to horseradish peroxidase to bind to the human IgG attached to the eggs. We then added 3,3'5,5'-tetramethylbenzidine base (TMB), which turns blue in the presence of horseradish peroxidase to detect the S. haematobium eggs. The RDT-Sh was compared in a blinded manner to urine microscopy. RESULTS: The RDT-Sh was positive in 89% of urine samples containing >1 egg/10 ml (58/65 samples) and 97% of urine samples containing >11 eggs/10 ml urine (35/36 samples) seen by microscopy. The RDT-Sh was negative 79% of the time when no eggs were seen on urine microscopy, but because up to three times more urine was used for the RDT-Sh, there were likely cases in which eggs were on the RDT-Sh filter but not detected by microscopy. We used latent class analysis incorporating urine microscopy, haematuria, proteinuria and RDT-Sh results to determine an overall 97% sensitivity and 78% specificity for RDT-Sh, 96% and 81% for urine microscopy, 71% and 98% for microscopic haematuria and 46% and 89% for proteinuria, respectively. CONCLUSIONS: The RDT-Sh is quick, inexpensive and easy to perform in the field for the diagnosis of S. haematobium.

Effective classification of the prevalence of Schistosoma mansoni.

OBJECTIVE: To present an effective classification method based on the prevalence of Schistosoma mansoni in the community. METHODS: We created decision rules (defined by cut-offs for number of positive slides), which account for imperfect sensitivity, both with a simple adjustment of fixed sensitivity and with a more complex adjustment of changing sensitivity with prevalence. To reduce screening costs while maintaining accuracy, we propose a pooled classification method. To estimate sensitivity, we use the De Vlas model for worm and egg distributions. We compare the proposed method with the standard method to investigate differences in efficiency, measured by number of slides read, and accuracy, measured by probability of correct classification. RESULTS: Modelling varying sensitivity lowers the lower cut-off more significantly than the upper cut-off, correctly classifying regions as moderate rather than lower, thus receiving life-saving treatment. The classification method goes directly to classification on the basis of positive pools, avoiding having to know sensitivity to estimate prevalence. For model parameter values describing worm and egg distributions among children, the pooled method with 25 slides achieves an expected 89.9% probability of correct classification, whereas the standard method with 50 slides achieves 88.7%. CONCLUSIONS: Among children, it is more efficient and more accurate to use the pooled method for classification of S. mansoni prevalence than the current standard method.