THE SUSCEPTIBILITY OF RECENT ISOLATES OF Schistosoma mansoni TO PRAZIQUANTEL

Abstract

Introduction: Schistosomiasis is a chronic disease caused by trematode flatworms of the genus Schistosoma and its control is dependent on a single drug, praziquantel (PZQ), but concerns over PZQ resistance have renewed interest in evaluating the in vitro susceptibility of recent isolates of Schistosoma mansoni to PZQ in comparison with well-established strains in the laboratory. Material and methods: The in vitro activity of PZQ (6.5-0.003 µg/mL) was evaluated in terms of mortality, reduced motor activity and ultrastructural alterations against S. mansoni. Results: After 3 h of incubation, PZQ, at 6.5 µg/mL, caused 100% mortality of all adult worms in the three types of recent isolates, while PZQ was inactive at concentrations of 0.08-0.003 µg/mL after 3 h of incubation. The results show that the SLM and Sotave isolates basically presented the same pattern of susceptibility, differing only in the concentration of 6.5 µg/mL, where deaths occurred from the range of 1.5 h in Sotave and just in the 3 h range of SLM. Additionally, this article presents ultrastructural evidence of rapid severe PZQ-induced surface membrane damage in S. mansoni after treatment with the drug, such as disintegration, sloughing, and erosion of the surface. Conclusion: According to these results, PZQ is very effective to induce tegument destruction of recent isolates of S. mansoni.

Human serum activates the tegument of female schistosomes and supports recovery from Praziquantel

“…Male and female_single schistosomes in NHSi after PZQ showed pronounced alterations of the tegument and the structures below including muscle shrinkage, vacuolization, blebs, and production of membrane bodies after PZQ exposure. Due to the sublethal dose of PZQ, used in this study, these alterations are less severe than described previously (Shaw and Erasmus 1983;Mendonça et al 2016;Matos-Rocha et al 2016). Taken into account the increased membrane activity in combination with the pronounced surface enlargement of female worms, it could be assumed that this might be advantageous for the survival within the human blood as well as the regeneration capacity after PZQ compared to male worms.…”

<p><em>Cucurbita pepo</em> Seed Oil Induces Microsatellite Instability and Tegumental Damage to <em>Schistosoma mansoni</em> Immature and Adult Worms In vitro</p>

“…Disruption to the integument of the parasite exposes the worms to the immune system of the host and thus interferes with their survival. 44 Many schistosomulum medications currently in use, such as PZQ, 45 mefloquine, 46 and artemether, 47 cause damage to the schistosomal integument.…”

Antiparasitic effects of ethanolic extracts of Piper arboreum and Jatropha gossypiifolia leaves on cercariae and adult worms of Schistosoma mansoni

“…In the positive control group, a sub-lethal dose of PZQ (0.5 μ g mL −1 ) was used, as described by Mendonça et al . (2016). In the negative control group (C-), only complete RPMI medium was used.…”

“…For this assay, one worm couple was added per well along with 50 μg mL −1 of extract for 30 h (test groups). In the positive control group, a sub-lethal dose of PZQ (0.5 μg mL −1 ) was used, as described by Mendonça et al (2016). In the negative control group (C-), only complete RPMI medium was used.…”