ABSTRACT
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.
ABSTRACT
Com a ampliação e a frequência das campanhas de desparasitação contra os geo-helmintos Ascaris lumbricoides, Trichuris trichiura, ancilostomídeos e Strongyloides stercoralis, ocorreu, como esperado, a redução da prevalência e da morbidade associada a estas parasitoses. Entretanto, alterações no perfil parasitológico das populações com redução dos helmintos e aumento significativo das protozooses intestinais se tornaram evidentes em todo o mundo. Além disso, a redução de carga parasitária tem dificultado o diagnóstico de rotina por meio de técnicas microscópicas de baixa sensibilidade. Neste artigo trazemos atualizações sobre algumas técnicas diagnósticas, como a Técnica de Sedimentação Espontânea em Tubo (SSTT), FLOTAC/Mini-FLOTAC e a otimização do método de Kato-Katz, além de alternativas viáveis para aumentar a sensibilidade dos métodos e tornar o diagnóstico das parasitoses intestinais mais preciso.
With the expansion and increased frequency of deworming against soil-transmitted helminths Ascaris lumbricoides, Trichuris trichiura, hookworms and Strongyloides stercoralis, there was, as expected, a reduction in the prevalence and morbidity associated with these diseases. However, changes in the parasitological profile of populations, with a reduction in helminths and a significant increase in intestinal protozoa, became evident worldwide. In addition, the reduction in the parasitic burden has made routine diagnosis difficult through low-sensitivity microscopic techniques. In this article we bring updates on diagnostic techniques, such as spontaneous sedimentation technique in tube (SSTT), FLOTAC/Mini-FLOTAC and optimization of Kato-Katz technique, as well as viable alternatives to increase the sensitivity of methods and make the diagnosis of intestinal parasites more accurate.
Subject(s)
Feces/parasitology , Helminthiasis , Chemoprevention , Clinical Laboratory TechniquesABSTRACT
The development of T follicular helper cells (Tfh) is a multifactorial process that occurs in multiple stages. After their activation the Tfh cells interact with the B cells to complete their differentiation. During this process, the Tfh cells begin to express canonical molecules such as the transcription factor B-cell lymphoma 6 protein, the CXC chemokine receptors type 5, and the inducible T-cell costimulator, as well as secreting other molecules such as IL-21. This whole process is regulated positively and negatively by several factors so that the best response is offered in the face of diseases of various origins, among them helminthiasis. In this context, the role of circulating Tfh, IL-4 and IgG subtypes is essential for an effective response against these pathogens. In this review, the migration process and the differentiation of Tfh, the regulation, their cell subtypes and the role of Tfh in the context of helminth infections will be addressed.
