Overview

Schistosomiasis is a neglected tropical disease caused by a trematode of the genus Schistosoma. The majority of human infections are attributable to the three species: S. haematobium, S. mansoni and S. japonicum (1). For S. mansoni, some eggs leave the body in the faeces and hatch in water to liberate miracidium larvae, which infect certain types of freshwater snails (2). Within the snail, the parasites multiply asexually to produce free-swimming cercariae larvae, and these then infect people by skin penetration (3). The adults do not multiply in the body but instead live there for several years, producing eggs (4).

Schistosomiasis infection constitutes a major public health problem, particularly in countries where the disease is endemic. Worldwide (Figure 1), it is estimated 779 million people at the risk of contracting schistosomiasis, while about 210 million are infected with the disease (5). The acute or short-term consequences of schistosomiasis infection include skin rashes, fever and fatigue, while chronic or long-term effects involve damage to internal organs such as the liver, spleen and gall bladder.

Traditionally, the schistosomiasis diagnosis has been performed by direct parasitological techniques, such as the Kato–Katz method (6). However, in cases of a low infections the Kato-Katz method is not efficient and may be detected by means of serological immunodiagnostic tests or molecular techniques (7–10). Alternative methods for the schistosomiasis diagnosis can potentially be identified through metabolomics studies, wherein the metabolites found associated with Schistosoma infections (e.g., in an animal’s blood, stool or urine) are profiled to identify characteristic biomarkers.

Results

This study used the methyl chloroformate (MCF) methodology as described by Smart et al., 2010 (11) to do the metabolomics analysis. The samples were obtained from three groups of 5 mice (Figure 3). Two groups infected (low and high parasitological load) and one group not infected (used as a control).
The metabolic profile was different between groups with some metabolites contributing to these differences (Figure 4), like Hippuric acid and Alanine. The Hippuric acid was related to a low load infection as the Alanine was related to a high load infection (Figure 5).
Previous studies found similar results using different techniques (Wang et al., 2004, García-Pérez et al., 2008 and Li et al., 2011 (12–14)) showing the relevance of these metabolites to possible be used as biomarkers for schistosomiases diagnosis.