Evidences for clustering of Schistosoma mansoni eggs in the sediment produced by Helmintex

Abstract

Diagnosis of schistosomiasis in low intensity transmission areas requires the improvement of methods in order to overcome the lack of sensitivity of classical coproparasitological methods. Helmintex is a new method based on the interaction of Schistosoma mansoni eggs with paramagnetic beads in a magnetic field. A preliminary seeding experiment gave support to a previous impression from routine examinations with Helmintex that eggs are usually found in the bottom half rather than in the upper half of the column of the sediment under examination. Nine replicas of one hundred eggs were seeded in uninfected 30g feces and each replica was submitted to Helmintex. The top 40 ?L aliquots of sediment were removed and sequentially examined under the microscope for enumeration of eggs. In 6 samples most of the eggs were found at the bottom half. This interesting finding may lead to an improved final step on egg isolation and better sensitivity for coproscopic diagnosis of schistosomiasis.