Recent therapeutic approaches in control of parasitic diseases with special reference to schistosomiasis

Control of schistosomiasis relies on a single drug, praziquantel (PZQ). Given the rising concerns about the potential emergence of PZQ-resistant strains, it has now become necessary to search for novel therapeutics. Efforts have been made for developing new schistosomicidal drugs, or testing existing drugs originally used for non-related diseases. However, the current pace for antischistosomal drug discovery is slow; hence, repositioning of existing approved drugs can offer a safe, rapid and cost effective solution. The literature regarding antischistosomal compounds contains a large number of natural products screened for their schistosomicidal properties. However, only a few of these may be promising drug leads in the development of a therapeutic reserve for schistosomiasis. Therefore, it is important to continue to identify new drugs and to explore alternative strategies to improve screening efficacy. Most of the extracts or natural compounds were only evaluated with In vitro studies; it is expected that they will be evaluated using in vivo experimental models. Further, it must be mentioned that the results of In vitro assays with many drugs do not correspond to what is observed in vivo; however, In vitro screening could identify novel anthelmintics that could eventually translate into practical applications. Thus, while In vitro tests are recommended initially, the assessment of therapeutic activity using in vivo models should be performed. The analysis of the S. mansoni genome and transcriptome offers great possibilities for identifying possible new drug targets and will facilitate further exploration of differences between host and parasite metabolic pathways. In addition to the isolation and structural determination of new drugs from natural products and information from the originating plant, the integration of the pharmacological properties of natural products with the functional genomics and proteomic studies in schistosome and In vitro screening methods with improved automatic high-content screening will be important tools to identify possible new drugs in the future and shed light on the approaches of helminth chemotherapy.