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Optimization of the Helmintex method for schistosomiasis diagnosis

Favero, Vivian, Frasca Candido, Renata Russo, De Marco Verissimo, Carolina, Jones, Malcolm K., St. Pierre, Timothy G., Lindholz, Catieli Gobetti, Da Silva, Vinicius Duval, Morassutti, Alessandra Loureiro, Graeff-Teixeira, Carlos
Experimental parasitology 2017 v.177 pp. 28-34
Schistosoma mansoni, detergents, eggs, epidemiological studies, feces, magnetic fields, medical treatment, polysorbates, schistosomiasis, screening, sediments
A diagnostic test that is reliable, sensitive, and applicable in the field is extremely important in epidemiological surveys, during medical treatment for schistosomiasis, and for the control and elimination of schistosomiasis. The Helmintex (HTX) method is based on the use of magnetic beads to trap eggs in a magnetic field. This technique is highly sensitive, but the screening of fecal samples consumes lots of time, thus delaying the results, especially in field studies. The objective of this work was to determine the effects of incorporation of the detergent Tween-20 into the method in an attempt to decrease the final pellet volume produced by the HTX method as well as the use of ninhydrin to stain the Schistosoma mansoni eggs. We showed that these modifications reduced the final volume of the fecal sediment produced in the last step of the HTX method by up to 69% and decreased the screening time to an average of 10.1 min per sample. The use of Tween 20 and ninhydrin led to a high percentage of egg recovery (27.2%). The data obtained herein demonstrate that the addition of detergent and the use of ninhydrin to the HTX process can optimize the screening step and also improve egg recovery, thus justifying the insertion of these steps into the HTX method.