Modifications to the parasitological technique of Rugai increase the diagnostic sensitivity for strongyloidiasis.

Strongyloidiasis is a neglected tropical disease caused mainly by Strongyloides stercoralis, a nematode that can persist for decades in the human host with a very low parasitic burden and without specific symptoms. Hence, it is difficult to diagnose and control. Larval concentration and culture methods with fecal samples show higher sensitivity for the diagnosis of Strongyloides-infected individuals; however, these techniques are not routinely used, primarily due to the challenges associated with processing a substantial volume of fecal samples. In the current study, we comparatively evaluated the sensitivity and applicability of modifications made to the Rugai parasitological method for the diagnosis of strongyloidiasis in fecal samples of experimentally infected rats and in 68 individuals from an urban community close to Maceió, Brazil. The presence and quantity of parasite larvae in the feces were comparatively evaluated using different parasitological techniques. In the experimental model, we demonstrated that the modified Rugai technique (RMOD) allowed for significantly higher recovery of larvae than the original Rugai technique (RO). Moreover, the sediment was cleaner and easier to evaluate using optical microscopy. Compared to other parasitological techniques, such as agar-plate culture (A-PC) and spontaneous sedimentation (SS), the RMOD technique showed higher sensitivity in the detection of larvae in all infected groups and presented comparatively better performance, especially in rats with a low parasite burden. In the human population, among the 68 stool samples evaluated, Strongyloides larvae were detected in the feces of six individuals with an estimated prevalence of 8.82%. However, the performance of each parasitological method was remarkably different. SS identified Strongyloides larvae in only two individuals and A-PC in three, whereas RMOD was able to identify six infected individuals, resulting in sensitivities of 33.3%, 50%, and 100%, respectively. In conclusion, the modifications introduced to the Rugai technique resulted in improved sensitivity for the detection of Strongyloides spp. infections, especially in stool samples with a low parasite burden, in comparison with other routinely used parasitological techniques.

Evaluation of isotype-based serology for diagnosis of Schistosoma mansoni infection in individuals living in endemic areas with low parasite burden.

Intestinal schistosomiasis is a chronic and debilitating disease that affects public health systems worldwide. Control interventions to reduce morbidity primarily involve the diagnosis and treatment of infected individuals. However, the recommended Kato-Katz (KK) parasitological method shows low sensitivity in individuals with low parasite loads and is not useful for monitoring elimination of parasite transmission at later stages. In the current study, we evaluated the accuracy of serum reactivity levels of different immunoglobulin isotypes in an enzyme-linked immunosorbent assay (ELISA), utilizing Schistosoma mansoni crude extracts, with the aim to improve the diagnosis of infected individuals with low parasite loads. The serum reactivity of IgM and IgG subclass antibodies (IgG1, IgG3, and IgG4) against soluble adult worm and egg antigen preparations was evaluated in residents from a schistosomiasis-endemic area in northern Minas Gerais, Brazil. The parasitological status of the study population was determined through fecal examination with multiple parasitological tests to create a consolidated reference standard (CRS) plus a fecal DNA detection test (q-PCR). Twelve months after praziquantel treatment, a second serum sample was obtained from the population for reexamination. A two-graph receiver operating characteristic curve (TG-ROC) analysis was performed using the serum reactivity of non-infected endemic controls and egg-positive individuals, and the cut-off value was established based on the intersection point of the sensibility and specificity curves in TG-ROC analyses. The diagnostic accuracy of each serological test was evaluated in relation to the parasitological CRS and to the combination of CRS plus qPCR results. The data revealed that serum reactivity of IgM and IgG3 against S. mansoni antigens did not allow identification of infected individuals from the endemic area. In contrast, serum IgG1 and IgG4-reactivity against schistosome antigens could distinguish between infected and non-infected individuals, with AUC values ranging between 0.728-0.925. The reactivity of IgG4 anti-soluble egg antigen - SEA (sensitivity 79 %, specificity 69 %, kappa = 0.49) had the best diagnostic accuracy, showing positive reactivity in more than 75 % of the infected individuals who eliminated less than 12 eggs per gram of feces. Moreover, serum IgG4 reactivity against SEA and against soluble worm antigen preparation (SWAP) was significantly reduced in the serum of infected individuals after 12 months of confirmed parasitological cure and in the absence of re-infection. These results reinforce that the described IgG4 anti-SEA ELISA assay is a sensitive alternative for the diagnosis of active intestinal schistosomiasis in individuals from endemic areas, including in those with a very low parasite load.

Schistosoma and Leishmania: An Untold Story of Coinfection.

A remarkable characteristic of infectious diseases classified as Neglected Tropical Diseases (NTDs) is the fact that they are mostly transmitted in tropical and subtropical regions with poor conditions of sanitation and low access to healthcare, which makes transmission areas more likely to overlap. Two of the most important NTDs, schistosomiasis and leishmaniasis, despite being caused by very different etiological agents, have their pathogenesis heavily associated with immune-mediated mechanisms, and Schistosoma spp. and Leishmania spp. have been shown to simultaneously infect humans. Still, the consequences of Schistosoma-Leishmania coinfections remain underexplored. As the inflammatory processes elicited by each one of these parasites can influence the other, several changes have been observed due to this coinfection in naturally infected humans, experimental models, and in vitro cell assays, including modifications in susceptibility to infection, pathogenesis, prognostic, and response to treatment. Herein, we review the current knowledge in Schistosoma-Leishmania coinfections in both human populations and experimental models, with special regard to how schistosomiasis affects tegumentary leishmaniasis, discuss future perspectives, and suggest a few steps to further improve our understanding in this model of parasite-host-parasite interaction.

Development and evaluation of an indirect ELISA using a multiepitope antigen for the diagnosis of intestinal schistosomiasis.

The laboratory diagnosis of intestinal schistosomiasis, carried out by detecting parasite eggs in feces, has low sensitivity when applied to individuals with low parasitic load. Serological tests can be more sensitive for the diagnosis of the disease. Therefore, the objective of this work was to develop and evaluate an ELISA-based immunoenzymatic assay, using a Schistosoma mansoni multiepitope antigen (ELISA IgG anti-SmME). For this, the amino acid sequences of S. mansoni cathepsin B and asparaginyl endopeptidase were submitted to the prediction of B cell epitopes and, together with peptide sequences obtained from earlier works, were used in the construction of a minigene. The multiepitope protein was expressed in Escherichia coli and the performance of the ELISA IgG anti-SmME for schistosomiasis was evaluated using serum samples from 107 individuals either egg positive or negative. In addition, 11 samples from individuals with other helminth infections were included. The ELISA IgG anti-SmME showed a sensitivity of 81.1% and a specificity of 46.1%. Further analysis revealed a 77.2% sensitivity in diagnosis of individuals with egg counts of ≤12 epg (eggs per gram feces) and 87.5% for individuals with 13­99 epg. It is worth mentioning that, to our knowledge, this was the first study using a multiepitope recombinant antigen in an ELISA for diagnosis of intestinal schistosomiasis, which demonstrated promising results in the diagnosis of individuals with low parasitic loads.

Accuracy Study of Kato-Katz and Helmintex Methods for Diagnosis of Schistosomiasis Mansoni in a Moderate Endemicity Area in Sergipe, Northeastern Brazil.

Schistosomiasis is a neglected tropical disease (NTD) caused by blood flukes from the genus Schistosoma. Brazil hosts the main endemic area in the Americas, where Schistosoma mansoni is the only species causing the disease. Kato-Katz (KK) thick smear is the WHO recommended screening test for populational studies, but there is growing evidence for the sensitivity limitations associated with KK, especially in areas with low parasite loads. Helmintex (HTX) is another highly sensitive egg-detection method, based on the magnetic properties of S. mansoni eggs and their isolation in a magnetic field. The objective of this study is to evaluate both KK and HTX in a moderate endemic locality, Areia Branca, located in the municipality of Pacatuba, in the state of Sergipe in northeastern Brazil. From 234 individual fecal samples, two KK thick smears were prepared and evaluated for each sample. Similarly, 30 g of each fecal sample was processed by HTX protocol. Eggs were detected in 80 (34.18%) residents. Twenty-three (9.83%) samples were positive for eggs (only by KK), and 77 (32.91%) samples showed positive for eggs (only by HTX). Sensitivity, specificity, and accuracy estimates gave values of 28.75%, 100% and 75.64%, respectively, for KK, and 96.25%, 100% and 98.72% respectively, for HTX. The positive predictive value was 100% for both methods, while the negative predictive value was 72.99% for KK and 98.09% for HTX. Overall, HTX presented a superior performance compared to the one sample, two slides KK examination. The study confirms the role of HTX as a reference method for the definition of true-positive samples in comparative accuracy studies and its potential role in the late stages when the certification of schistosomiasis transmission interruption is required. Diagnostic tests are important tools for the elimination of this NTD, besides the effective implementation of safe water, basic sanitation, snail control, and the treatment of infected populations.

Estado nutricional e segurança alimentar de famílias em vulnerabilidade social no município de Contagem, Minas Gerais, 2014 / Nutritional status and food security of socially vulnerable families in the municipality of Contagem, Minas Gerais, 2014

Este é um estudo transversal avaliando estado nutricional e insegurança alimentar em uma comunidade vulnerável de Contagem, região metropolitana de Belo Horizonte. Um total de 273 indivíduos de 67 famílias foram avaliados. Para a avaliação antropométrica, determinou-se o peso, a estatura, o índice de massa corporal, a circunferência da cintura e a razão cintura-estatura. A insegurança alimentar foi analisada por meio da Escala Brasileira de Insegurança Alimentar. As concentrações de colesterol total, triglicerídeos, glicose e albumina sérica também foram determinadas. Das 67 famílias avaliadas, 51% (n = 34) apresentaram insegurança alimentar, sendo 79,4% leve, 17,7% moderada e 2,9% grave. Em crianças e adolescentes, sobrepeso e obesidade foram diagnosticados em 9,3% (n = 4) e 19,5% (n=16), respectivamente. Entre os adultos, 34,1% (n = 42) foram classificados com sobrepeso, 27,6% (n = 34) com obesidade grau I e 59,3% (n = 73) apresentaram risco aumentado de doenças cardiovasculares. Nos idosos, o excesso de peso foi diagnosticado em 44,0% (n = 11) e 80,0% (n = 20) apresentaram risco aumentado para doenças cardiovasculares. Hiperglicemia, hipercolesterolemia e hipertrigliceridemia foram diagnosticadas em 17, 45 e 72% da população, respectivamente. Houve correlação positiva entre os parâmetros antropométricos e bioquímicos, com exceção da albumina e glicose, que apresentaram correlação negativa em crianças e adultos. Nosso estudo confirma o impacto da vulnerabilidade social na ocorrência de elevadas proporções de insegurança alimentar, ocasionando alta prevalência de sobrepeso e obesidade e risco aumentado para desordens cardiovasculares. Além disso, nossos achados endossam o uso de concentrações séricas de albumina como indicador de alterações no metabolismo da glicose.

This is a cross-sectional study evaluating nutritional status and food insecurity in a vulnerable community in Contagem, in the metropolitan region of Belo Horizonte. A total of 273 individuals from 67 families were evaluated. For the anthropometric assessment, weight, height, body mass index, waist circumference, and waist-to-height ratio were determined. Food insecurity was analyzed using the Brazilian Food Insecurity Scale. Total cholesterol, triglycerides, glucose, and serum albumin concentrations were also determined. Of the 67 families evaluated, 51% (n = 34) had food insecurity, of which 79.4% were mild, 17.7% were moderate, and 2.9% were severe. In children and adolescents, overweight and obesity were diagnosed in 9.3% (n = 4) and 19.5% (n = 16), respectively. Among adults, 34.1% (n = 42) were classified as overweight, 27.6% (n = 34) had grade I obesity, and 59.3% (n = 73) had an increased risk of cardiovascular disease. In the elderly, overweight was diagnosed in 44.0% (n = 11), and 80.0% (n = 20) had an increased risk for cardiovascular diseases. Hyperglycemia, hypercholesterolemia, and hypertriglyceridemia were diagnosed in 17, 45, and 72% of the population, respectively. There was a positive correlation between anthropometric and biochemical parameters, with the exception of albumin and glucose, which showed a negative correlation in children and adults. Our study confirms the impact of social vulnerability on the occurrence of high proportions of food insecurity, leading to a high prevalence of overweight and obesity and an increased risk for cardiovascular disorders. Furthermore, our findings support the use of serum albumin concentrations as an indicator of changes in glucose metabolism.

Previous History of American Tegumentary Leishmaniasis Alters Susceptibility and Immune Response Against Schistosoma mansoni Infection in Humans.

Schistosomiasis and Leishmaniasis are chronic parasitic diseases with high prevalence in some tropical regions and, due to their wide distribution, a risk of co-infections is present in some areas. Nevertheless, the impact of this interaction on human populations is still poorly understood. Thus, the current study evaluated the effect of previous American Tegumentary Leishmaniasis (ATL) on the susceptibility and immune response to Schistosoma mansoni infection in residents from a rural community in Northern of Minas Gerais state, Brazil, an area endemic for both parasitic infections. The participants answered a socioeconomic questionnaire and provided stool and blood samples for parasitological and immunological evaluations. Stool samples were examined by a combination of parasitological techniques to identify helminth infections, especially S. mansoni eggs. Blood samples were used for hemograms and to measure the serum levels of cytokines and chemokines. Reports on previous ATL were obtained through interviews, clinical evaluation forms, and medical records. S. mansoni infection was the most prevalent parasitic infection in the study population (46%), and the majority of the infected individuals had a very low parasite burden. In the same population, 93 individuals (36.2%) reported previous ATL, and the prevalence of S. mansoni infection among these individuals was significantly higher than among individuals with no ATL history. A multiple logistic regression model revealed that S. mansoni infection was positively associated with higher levels of CCL3 and CCL17, and a higher frequency of IL-17 responders. Moreover, this model demonstrated that individuals with an ATL history had a 2-fold higher probability to be infected with S. mansoni (OR = 2.0; 95% CI 1.04-3.68). Among S. mansoni-infected individuals, the logistic regression demonstrated that a previous ATL history was negatively associated with the frequency of IL-17 responders and CXCL10 higher responders, but positively associated with higher IL-27 responders. Altogether, our data suggest that previous ATL may alter the susceptibility and the immune response in S. mansoni-infected individuals, which may likely affect the outcome of schistosomiasis and the severity of the disease in humans.

Use of Schistosoma mansoni soluble egg antigen (SEA) for antibody detection and diagnosis of schistosomiasis: The need for improved accuracy evaluations of diagnostic tools.

Many antigens for use in antibody-detection systems for schistosomiasis have been investigated over the past 40 years. In particular, soluble egg antigens (SEA) are still widely used in enzyme-linked immunosorbent assays (ELISAs) for detection of immunoglobulin classes and subclasses. Here, we conducted a literature review to examine accuracy evaluations of SEA-Immunoglobulin G (IgG)-ELISAs performed to detect Schistosoma mansoni infections and published between 1979 and 2019. S. mansoni is the main causative agent for intestinal schistosomiasis in many countries in Africa and Central and South America. After retrieving 214 relevant abstracts from the PubMed database, we selected 15 publications to undergo a full review. Sensitivity and specificity values varied from 71 to 99%, and from 6 to 100%, respectively. In addition, 11/15 studies did not state confidence intervals. Therefore, the findings from this review indicate that after four decades, we still do not have consistent evaluation estimates of SEA-IgG-ELISAs. Antigen mass per well and dilution of test sera in these articles varied from 0.018 µg to 1.5 µg, and from 1:50 to 1:500, respectively. Most of the reported accuracy evaluations used control sera which were selected based on parasitological examinations for egg detection, although ill-defined criteria were also noted. The number and composition of control serum panels was considered not adequate in approximately half of the studies. It is also noteworthy that among more than 30 diagnostic antigen preparations under development since the 1970s, most were not validated in the field and they failed to reach populations in need. Thus, attention to guidelines for standardization, estimations of accuracy, and reporting of results is needed to facilitate coordinated efforts aimed at schistosomiasis control and elimination.

The use of the circulating cathodic antigen (CCA) urine cassette assay for the diagnosis and assessment of cure of Schistosoma mansoni infections in an endemic area of the Amazon region.

INTRODUCTION: Schistosomiasis is a poverty-related disease that affects people in 78 countries worldwide. This study aimed to evaluate the point-of-care circulating cathodic antigen (POC-CCA) test performance using sensitive parasitological methods as a reference standard (RS) in individuals before and after treatment. METHODS: The RS was established by combining the results of 16 Kato-Katz slides and the Helmintex® method. Positivity rates of the POC-CCA test and Kato-Katz and Helmintex® methods were calculated before treatment and 30 days afterward. Furthermore, the sensitivity, specificity, accuracy, and kappa coefficient before treatment were determined by comparing the methods. The cure rate was defined 30 days after treatment. RESULTS: Among the 217 participants, the RS detected a total of 63 (29.0%) positive individuals. The POC-CCA test identified 79 (36.4%) infections. The evaluation of POC-CCA test performance in relation to the RS revealed a sensitivity of 61.9%, specificity of 74.0%, accuracy of 70.5%, and kappa coefficient of 0.33. Out of the 53 remaining participants after treatment, a total of 45 (81.1%) showed egg negative results, and 8 (18.9%) were egg positive according to the RS. A total of 5 (9.4%) egg-positive and 37 (69.8%) egg-negative individuals were positive by the POC-CCA test. CONCLUSIONS: Our data show that the POC-CCA test has potential as an auxiliary tool for the diagnosis of Schistosoma mansoni infection, yielding better results than 16 Kato-Katz slides from three different stool samples. However, the immunochromatographic test lacks sufficient specificity and sensitivity for verifying the cure rate after treatment.

Toxoplasma gondii: Cytokine responses in mice reinfected with atypical strains.

This study aimed to elucidate the cellular immune response against Toxoplasma gondii in chronically infected mice reinfected with different strains of the parasite to elucidate the immunological basis for chronicity or virulence and to uncover the involvement of genes that encode virulence proteins and modulate the immune response. BALB/c mice were infected by oral gavage with non-virulent D8 strain and challenged 45 days post-infection with virulent EGS or CH3 strains. Cytokine measurement was performed 2 days post-challenge in cell extracts of the small intestine and 2, 7, and 14 days post-challenge in serum. Virulence gene allele type of these strains was analyzed. Challenged mice survived by avoiding exacerbated inflammation and inhibiting the overproduction of cytokines. Local and systemic cytokine response in challenged mice was similar to chronic controls and quite distinct in mice acutely infected with the EGS or CH3 strains. Allelic combinations of the virulence genes ROP5/ROP18 was predictive of virulence in mice when tested in these T. gondii strains. Other allelic combinations of rhoptries and dense granules genes showed discrepancies.

Accuracy of real-time polymerase chain reaction to detect Schistosoma mansoni - infected individuals from an endemic area with low parasite loads.

Due to the efforts to control schistosomiasis transmission in tropical countries, a large proportion of individuals from endemic areas present low parasite loads, which hinders diagnosis of intestinal schistosomiasis by the Kato-Katz (KK) method. Therefore, the development of more sensitive diagnostic methods is essential for efficient control measures. The aim was to evaluate the accuracy of a real-time polymerase chain reaction (RT-PCR) to detect Schistosoma mansoni DNA in fecal samples of individuals with low parasite loads. A cross-sectional population-based study was conducted in a rural community (n = 257) in Brazil. POC-CCA® was performed in urine and feces were used for RT-PCR. In addition, fecal exams were completed by 18 KK slides, saline gradient and Helmintex techniques. The combined results of the three parasitological tests detected schistosome eggs in 118 participants (45.9%) and composed the consolidated reference standard (CRS). By RT-PCR, 117 out of 215 tested samples were positive, showing 91.4% sensitivity, 80.2% specificity and good concordance with the CRS (kappa = 0.71). RT-PCR identified 86.9% of the individuals eliminating less than 12 eggs/g of feces, demonstrating much better performance than POC-CCA® (50.8%). Our results showed that RT-PCR is a valuable alternative for the diagnosis of intestinal schistosomiasis in individuals with very low parasite loads.

The use of the circulating cathodic antigen (CCA) urine cassette assay for the diagnosis and assessment of cure of Schistosoma mansoni infections in an endemic area of the Amazon region

Abstract INTRODUCTION Schistosomiasis is a poverty-related disease that affects people in 78 countries worldwide. This study aimed to evaluate the point-of-care circulating cathodic antigen (POC-CCA) test performance using sensitive parasitological methods as a reference standard (RS) in individuals before and after treatment. METHODS The RS was established by combining the results of 16 Kato-Katz slides and the Helmintex® method. Positivity rates of the POC-CCA test and Kato-Katz and Helmintex® methods were calculated before treatment and 30 days afterward. Furthermore, the sensitivity, specificity, accuracy, and kappa coefficient before treatment were determined by comparing the methods. The cure rate was defined 30 days after treatment. RESULTS Among the 217 participants, the RS detected a total of 63 (29.0%) positive individuals. The POC-CCA test identified 79 (36.4%) infections. The evaluation of POC-CCA test performance in relation to the RS revealed a sensitivity of 61.9%, specificity of 74.0%, accuracy of 70.5%, and kappa coefficient of 0.33. Out of the 53 remaining participants after treatment, a total of 45 (81.1%) showed egg negative results, and 8 (18.9%) were egg positive according to the RS. A total of 5 (9.4%) egg-positive and 37 (69.8%) egg-negative individuals were positive by the POC-CCA test. CONCLUSIONS Our data show that the POC-CCA test has potential as an auxiliary tool for the diagnosis of Schistosoma mansoni infection, yielding better results than 16 Kato-Katz slides from three different stool samples. However, the immunochromatographic test lacks sufficient specificity and sensitivity for verifying the cure rate after treatment.

Discrepancy between batches and impact on the sensitivity of point-of-care circulating cathodic antigen tests for Schistosoma mansoni infection.

The Kato-Katz (KK) technique is the mainstay mapping tool for the diagnosis of Schistosoma mansoni infection, despite showing poor sensitivity in cases of low-intensity infections. As an alternative, a rapid point-of-care circulating cathodic antigen diagnostic test (POC-CCA) has been commercially developed that involves a simple urine assay to detect S. mansoni, rather than a stool-based parasitological examination. Although POC-CCA has proven to be a more sensitive test than KK, it is not yet clear how to interpret discordant results between the two tests, particularly for situations in which the KK result is positive and the POC-CCA result is negative. Thus, the objective of this study was to evaluate the degree of diagnostic variability between different POC-CCA batches with respect to results obtained with KK. For this purpose, we collected urine and stool samples of school-aged children from areas of low and moderate endemicity in Brazil, and compared different POC-CCA batches results with those of KK-positive individuals. We found a statistically significant difference between the results obtained from various POC-CCA batches using the same urine samples, regardless of the degree of endemicity and the intensity of infection in positive KK samples. In addition, there was poor agreement between the KK and POC-CCA results in some batches of the rapid test, resulting in false negatives. These findings raise concerns around quality control checks of POC-CCA, especially in light of the high cost and increasing reliance on this new diagnostic method as control programs move towards a goal of elimination.

Concordance of the point-of-care circulating cathodic antigen test for the diagnosis of intestinal schistosomiasis in a low endemicity area.

BACKGROUND: The Kato-Katz technique is recommended worldwide for the diagnosis of intestinal schistosomiasis, detecting parasite eggs in feces of infected people. However, new tests have been developed in order to facilitate diagnosis, e.g. by detection of specific antigens secreted by schistosomes, such as the circulating cathodic antigen (CCA). The aim of this study was to evaluate the performance of the point-of-care circulating cathodic antigen test (POC-CCA) compared to the Kato-Katz technique in a low prevalence area in the Amazon Region, located in the municipality of Primavera, State of Pará, Brazil. METHODS: Positivity rates of the POC-CCA test and the Kato-Katz technique were calculated. The sensitivity, specificity, accuracy and kappa coefficient were determined by comparing both methods. The reference standard was established using 16 Kato-Katz slides, 12 of the first fecal sample, two of the second and two of the third one. The study also included the concordance between POC-CCA results and different numbers and combinations of Kato-Katz slides. RESULTS: The prevalence of schistosomiasis according to the reference standard or POC-CCA test reached a rate of 9.4% or 23.9%, respectively, among a total of 372 participants. The positivity rates by the Kato-Katz technique increased from 2.4 to 9.4%, according to the increase in the number of slides examined and fecal samples collected. A sensitivity of 55.6%, specificity 76.9%, accuracy 76% and κ coefficient of 0.06 was observed by comparing one slide of the first sample and POC-CCA. Comparing 6 slides from three different samples, two slides of each, with POC-CCA resulted in a sensitivity of 58.3%, specificity 78.4%, accuracy 77% and κ coefficient of 0.16. Finally, the comparison of 16 slides from three different samples with POC-CCA revealed a sensitivity of 65.7%, specificity 80.4%, accuracy 79%, and κ coefficient of 0.27. CONCLUSIONS: The immunochromatographic test has the potential to be an important tool to combat schistosomiasis because of its practicality and applicability but should be applied with caution in low prevalence areas and in programs that aim to eliminate this disease. TRIAL REGISTRATION: CAAE#21824513.9.0000.5091 . January 31st, 2014.

Identification of priority areas for surveillance of cutaneous leishmaniasis using spatial analysis approaches in Southeastern Brazil.

BACKGROUND: Cutaneous leishmaniasis (CL) is an important public health problem in Brazil and in several tropical regions of the world. In the Americas, Brazil is the country with the highest number of registered cases. In Brazil, the state of Minas Gerais has the highest number of cases in the southeastern region. In the present study, we used spatial analysis in the State of Minas Gerais to identify municipalities of priority during a nine-year period (2007-2015), which might be used to guide surveillance and control measures. METHODS: An ecological study with spatial analysis of autochthonous cases of CL was performed in the state of Minas Gerais between 2007 and 2015. We calculated incidence rates, used Empirical Bayesian smoothing for each municipality, and divided the analyses into three-year intervals. In order to analyze the existence of spatial autocorrelation, and to define priority areas, Moran's Global Index and Local Indicators of Spatial Association (LISA) were used. RESULTS: The mean incidence rate for the entire state was 6.1/100,000 inhabitants. For Minas Gerais, analysis of CL cases over time revealed a successive increase of indicated mesoregions with high priority municipalities. Eight of the designated mesoregions contained municipalities classified as high priority areas in any of the three evaluated trienniums, and four mesoregions had high priority municipalities throughout the entire investigation. CONCLUSIONS: Within the southeastern region of Brazil, Minas Gerais State stands out, with highest CL incidence rates. Using spatial analysis, we identified an increasing numbers of cases in the municipalities classified as high priority areas in different mesoregions of the state. This information might be of value to direct surveillance and control measures against CL and to understand the dynamics of the expansion of CL in Minas Gerais. Similar approaches might be used to map CL in other regions throughout Brazil, or in any other country, where national notification and control programs exist.

Evaluation of diagnostic methods for the detection of intestinal schistosomiasis in endemic areas with low parasite loads: Saline gradient, Helmintex, Kato-Katz and rapid urine test.

BACKGROUND: In some tropical countries, such as Brazil, schistosomiasis control programs have led to a significant reduction in the prevalence and parasite burden of endemic populations. In this setting, the Kato-Katz technique, as the standard diagnostic method for the diagnosis of Schistosoma mansoni infections, which involves the analysis of two slides from one fecal sample, loses its sensitivity. As a result, a significant number of infected individuals are not detected. The objective of this study was to perform extensive parasitological testing of up to three fecal samples and include a rapid urine test (POC-CCA) in a moderate prevalence area in Northern Minas Gerais, Brazil, and evaluate the performance of each test separately and in combination. METHODS AND FINDINGS: A total of 254 individuals were examined with variants of the standard Kato-Katz technique (up to18 Kato-Katz slides prepared from three fecal samples), a modified Helmintex (30 g of feces), the saline gradient (500 mg of feces), and the POC-CCA methods. We established a reference standard taking into consideration all the positive results in any of the parasitological exams. Evaluation of the parasite burden by two Kato-Katz slides confirmed that most of the individuals harbored a light infection. When additional slides and different parasitological methods were included, the estimated prevalence rose 2.3 times, from 20.4% to 45.9%. The best sensitivity was obtained with the Helmintex method (84%). All parasitological methods readily detected a high or moderate intensity of infection; however, all lost their high sensitivity in the case of low or very low intensity infections. The overall sensitivity of POC-CCA (64.9%) was similar to the six Kato-Katz slides from three fecal samples. However, POC-CCA showed low concordance (κ = 0.34) when compared with the reference standard. CONCLUSIONS: The recommended Kato-Katz method largely underestimated the prevalence of S. mansoni infection. Because the best performance was achieved with a modified Helmintex method, this technique might serve as a more precise reference standard. An extended number of Kato-Katz slides in combination with other parasitological methods or with POC-CCA was able to detect more than 80% of egg-positive individuals; however, the rapid urine test (POC-CCA) produced a considerable percentage of false positive results.

Schistosomiasis in the Amazon region: is the current diagnostic strategy still appropriate?

Abstract INTRODUCTION: This study analyzed the performance of the Kato Katz technique in detecting intestinal schistosomiasis in the State of Pará. METHODS: Of three stool samples provided by each of 380 participants, a total of 16 Kato Katz slides were examined to define the reference value (RV) of positives for comparisons. RESULTS: The RV revealed 37 (9.7%) infected participants in contrast to 10 (2.6%) according to a single slide. CONCLUSIONS: This significant underestimation of the infection rate gives reason to discuss if the current classification of prevalence levels reflects the real situation, principally in low transmission areas, like the Amazon region.

Schistosomiasis in the Amazon region: is the current diagnostic strategy still appropriate?

INTRODUCTION: This study analyzed the performance of the Kato Katz technique in detecting intestinal schistosomiasis in the State of Pará. METHODS: Of three stool samples provided by each of 380 participants, a total of 16 Kato Katz slides were examined to define the reference value (RV) of positives for comparisons. RESULTS: The RV revealed 37 (9.7%) infected participants in contrast to 10 (2.6%) according to a single slide. CONCLUSIONS: This significant underestimation of the infection rate gives reason to discuss if the current classification of prevalence levels reflects the real situation, principally in low transmission areas, like the Amazon region.

Identification of immunodominant antigens for the laboratory diagnosis of toxocariasis.

OBJECTIVES: To identify immunodominant antigens of Toxocara canis recognised by Toxocara-infected sera as recombinant reagents for immunodiagnosis of toxocariasis. METHODS: Pooled sera from human cases of toxocariasis were used to identify immunodominant antigens by immunoscreening a T. canis larval expression cDNA library. The positive clones were sequenced to reveal the identity of the antigens. The recombinant proteins were expressed in E. coli and then used to confirm their immunoreaction with sera of humans with toxocariasis. Two chosen antigens were also used to differentiate Toxocara infection from other helminth infections in mice. RESULTS: Eleven antigens with immunodiagnostic potential were identified, including two C-type lectins (CTLs) that reacted strongly with the Toxocara-positive serum pool. The first CTL (Tc-CTL-1) is the same as TES-32, previously identified as a major immunodominant component of TES; the second CTL (Tc-CTL-2) is a novel C-type lectin sharing 83% amino acid sequence identity within the functional domain of Tc-CTL-1. The E. coli-expressed recombinant Tc-CTL-1 was strongly recognised by the Toxocara-positive serum pool or sera from animals experimentally infected with T. canis. Reactivity with recombinant Tc-CTL-1 was higher when the unreduced protein was used in an enzyme-linked immunosorbent assay (ELISA), dot-blot assay or Western blot test compared to the protein under reduced condition. Both recombinant Tc-CTL-1- and Tc-CTL-2-based ELISAs were able to differentiate T. canis infection from other helminth infections in experimentally infected mice. CONCLUSIONS: Both Tc-CTL-1 and Tc-CTL-2 were able to differentiate Toxocara infection from other helminth infections and could potentially be used as sensitive and specific immunodiagnostic antigens.