Aprimoramento do método Helmintex® para diagnóstico da infecção por Schistosoma mansoni baseado na detecção de ovos

Abstract

Human schistosomiasis is considered one of the most devastating tropical diseases, affecting about 250 million people around the world. For this reason, it is considered the second most important parasitic diseases in terms of socio-economic effects, losing only to malaria. In Brazil, Schistosoma mansoni is the only etiological agent of schistosomiasis, affecting 19 States. In areas of recent disease introduction or where the control occurs, low parasite burden is a reality and its detection is hampered by the low sensitivity of the available diagnostic methods. Helmintex® is a recently proposed method that uses a large amount of feces, numerous concentration steps, and addition of paramagnetic particles, conveying high sensitivity for the detection of eggs of S. mansoni in feces. However, it is a laborious process, with limited application in the field and delayed delivery of the diagnosis. The objective of this thesis is the improvement of egg detection methodologies for the diagnosis of schistosomiasis, mainly seeking the improvement of the Helmintex® methodology. Thus, the first chapter of this thesis proposes the reduction of the final Helmintex® sediment, with the use of neutral detergent, Tween 20, and the staining of S. mansoni eggs with ninhydrin, aiming to optimize the methodology. The second chapter investigates the use of a chemiluminescent reaction for the detection of S. mansoni eggs in the final Helmintex® sediment, aiming to speed up the final diagnosis. Finally, the third chapter explores the peculiarities of eggs and their passage through the intestinal wall, observing their clustering and the secretion by the eggs of a protein called Sm 16. The results obtained in this work reinforce the proposed role of the Helmintex method, to serve as a reference for the diagnosis of intestinal schistosomiasis, and for the comparative evaluation of other tests, in addition to registering for the first time, the formation of cluster and the excretion of the protein Sm16 by S. mansoni eggs during their migration through the intestinal wall of mice.