Performance of POC-CCA® in diagnosis of schistosomiasis mansoni in individuals with low parasite burden

Abstract: INTRODUCTION: Schistosomiasis, caused by Schistosoma mansoni, is a public health concern in Brazil. However, the most popular diagnostic method, the Kato-Katz technique, exhibits low sensitivity in low-endemicity areas. We aimed to compare the performance of an immunological assay, the point-of-care circulating cathodic antigen (POC-CCA®) test, with that of two parasitological techniques in a low-endemicity population. METHODS: Our study included 141 individuals living in Estreito de Miralta, Minas Gerais, Brazil. Fecal samples were obtained from all participants and analyzed for schistosomiasis using two parasitological techniques: the Kato-Katz technique and the saline gradient technique. Additionally, POC-CCA® strips were utilized for testing urine samples. The results obtained by the different techniques were compared. RESULTS: Analysis of two or 24 slides using the Kato-Katz technique resulted in a positivity rate of 10.6% (15/141) or 19.1% (27/141), respectively. The saline gradient technique yielded a positivity rate of 17.0% (24/141). The prevalence according to both parasitological techniques was 24.1% (34/141). The POC-CCA® test yielded a positivity rate of 22.7% (32/141); however, the positivity rate was merely 2.1% if trace results were considered negative. The agreements observed between POC-CCA® and the parasitological techniques were good (Kappa indexes > 0.64). The POC-CCA® test was more sensitive than the two-slide Kato-Katz technique (p < 0.05) in detecting cases of S. mansoni infection when trace results were considered positive. CONCLUSIONS: These findings reinforce the importance of using multiple diagnostic techniques in low-endemicity areas for effective control of disease.

Evaluation of parasitological and molecular techniques for the diagnosis and assessment of cure of schistosomiasis mansoni in a low transmission area

This study evaluated parasitological and molecular techniques for the diagnosis and assessment of cure of schistosomiasis mansoni. A population-based study was performed in 201 inhabitants from a low transmission locality named Pedra Preta, municipality of Montes Claros, state of Minas Gerais, Brazil. Four stool samples were analysed using two techniques, the Kato-Katz® (KK) technique (18 slides) and the TF-Test®, to establish the infection rate. The positivity rate of 18 KK slides of four stool samples was 28.9% (58/201) and the combined parasitological techniques (KK+TF-Test®) produced a 35.8% positivity rate (72/201). Furthermore, a polymerase chain reaction (PCR)-ELISA assay produced a positivity rate of 23.4% (47/201) using the first sample. All 72 patients with positive parasitological exams were treated with a single dose of Praziquantel® and these patients were followed-up 30, 90 and 180 days after treatment to establish the cure rate. Cure rates obtained by the analysis of 12 KK slides were 100%, 100% and 98.4% at 30, 90 and 180 days after treatment, respectively. PCR-ELISA revealed cure rates of 98.5%, 95.5% and 96.5%, respectively. The diagnostic and assessment of cure for schistosomiasis may require an increased number of KK slides or a test with higher sensitivity, such as PCR-ELISA, in situations of very low parasite load, such as after therapeutic interventions.

Acute schistosomiasis diagnosis: a new tool for the diagnosis of schistosomiasis in a group of travelers recently infected in a new focus of Schistosoma mansoni

Introduction The diagnosis of schistosomiasis mansoni on early stages of infection is important to prevent late morbidity. A simple, cheap, sensitive and specific assay for routine diagnosis of schistosome infection based on the detection of specific IgG for schistosomula tegument antigens (ELISA-SmTeg) was developed by our group. Methods We describe here an acute outbreak involving a travel group of 80 individuals from a non-endemic area of the State of Minas Gerais, Brazil. These individuals were in contact with a freshwater pool where Biomphalaria glabrata was found. Results obtained from our new methodology were compared to IgG antibody titers against soluble worm antigenic preparation (SWAP) by ELISA and, also to parasitological examination, nuclear magnetic resonance and clinical findings. Results ELISA-SmTeg was capable of detecting 64 positive cases among the 80 individuals participating at the survey with a positivity ratio of 80% and a higher sensitivity than ELISA-SWAP that was only sensitive for 56% of positive cases. Besides, a significant correlation was found for the severity of the infection and the specific IgG titers against SmTeg. Conclusions Our data showed that ELISA-SmTeg might serve as the initial diagnostic tool for acute stages of the infection in community-based helminth control programs or for the surveillance of individuals from non-endemic areas. .

Evaluation of two coproscopic techniques for the diagnosis of schistosomiasis in a low-transmission area in the state of Minas Gerais, Brazil

This population study, which evaluated two parasitological methods for the diagnosis of schistosomiasis mansoni, was performed in a low-transmission area in Pedra Preta, Montes Claros, Minas Gerais, Brazil. A total of 201 inhabitants of the rural area participated in this research. Four stool samples were obtained from all participants and analysed using the Kato-Katz method (18 slides) and a commercial test, the TF-Test®, which was performed quantitatively. The data were analysed to determine prevalence, the sensitivity of the diagnostic methods, the worm burden and the definition of the "gold standard", which was obtained by totalling the results of all samples examined using the Kato-Katz technique and the TF-Test®. The results showed that the prevalence obtained from the examination of one Kato-Katz slide (the methodology adopted by the Brazilian control programme) was 8 percent compared to 35.8 percent from the "gold standard", which was a 4.5-fold difference. This result indicates that the prevalence of schistosomiasis in so-called low-transmission areas is significantly underestimated.

Schistosoma mansoni: ação da lovastatina no modelo murino / Schistosoma mansoni: the action of lovastatin on the murine model

Aimed to evaluate the lovastatin action on Schistosoma mansoni oviposition, infected mice with 100 plus minus 10 cercariae of the LE strain were used. Thirty days after infection the animals were treated with 100, 200 and 400mg/kg of lovastatin, per os, during five consecutive days and then sacrificed 7, 15, 30 or 60 days after treatment. We analyzed: distribution of worms in mesenteries and liver; mortality of worms in the liver; alteration of the oogram; eggs counting in the jejunum and liver; presence of intrauterine eggs and morphology of the worms from the treated and control groups (infected and not treated animals). Significant statistical differences were found between treated and control groups when the presence of intrauterine eggs was considered and also, alteration on the oogram, eggs at different stages of development in jejunum, liver and in the body length of males and females. The morphological study of the worms showed that the degenerative modifications occurred, mainly in the reproductive system, with reduction and alteration of the viteline follicles and the ovary of the females. Also modifications in the males testicles were observed. The results suggest that the drug under study reduces, considerably, the female S. mansoni, oviposition increases the worms' size, leads to alteration in the reproductive system of males and females. It also may induce death of a significant part of the worm populations at the dose of 400mg/kg.