Abstract This review synthesizes recent advances in the discovery of schistosomicidal candidates, with particular emphasis on the medicinal chemistry of heterocyclic scaffolds and the identification of novel molecular targets. To this end, a contextual bibliometric assessment of the literature indexed in the Web of Science and Scopus databases was conducted, considering the chemical classes investigated, antiparasitic activity, parasite life stages evaluated, mechanistic evidence, biological targets explored, and the translational potential of the compounds. Overall, recent studies indicate that the discovery of new agents against Schistosoma mansoni still relies heavily on in vitro and in vivo phenotypic screening approaches. Nevertheless, target-based strategies have gained increasing prominence, particularly those focused on pathways essential for parasite survival, including epigenetic regulation, redox homeostasis, detoxification, nucleotide metabolism, tegument integrity, and neuromuscular function. Heterocyclic compounds, especially those containing nitrogen and sulphur atoms, have emerged as privileged scaffolds owing to their structural diversity, ease of chemical optimization, and ability to interact with multiple biological targets. The analysis also highlights the growing incorporation of computational chemistry, molecular modelling, and ADMET prediction tools in the prioritization of chemical series. Despite these advances, important gaps remain regarding the integration of structure–activity relationship (SAR) studies, target validation, elucidation of mechanisms of action, evaluation across different stages of the parasite life cycle, pharmaceutical formulation development, and pharmacokinetic and pharmacodynamic characterization. Strengthening these aspects is essential to translate promising compounds into clinically relevant candidates capable of overcoming the limitations of praziquantel-based therapy.
Abstract Urinary schistosomiasis caused by Schistosoma haematobium may mimic bladder malignancy in patients evaluated outside endemic regions. We report a 20-year-old Somali university student who had been living in Türkiye for two years and had a history of freshwater exposure in Somalia. He presented with painless macroscopic haematuria and lower urinary tract symptoms. An initial 50-mL urine sample collected at 11:00 showed no parasitic structures; a repeat 20-mL terminal-stream sample collected at 13:30 on the same day revealed characteristic terminal-spined S. haematobium eggs on unstained light microscopy of centrifuged urine sediment. Cystoscopy demonstrated an approximately 2-cm sessile bladder lesion suspicious for malignancy and diffuse yellowish granular mucosal lesions (‘sandy patches’). Transurethral resection revealed eosinophil-rich chronic active cystitis and subepithelial schistosome eggs without dysplasia or malignancy. The patient received praziquantel. This case illustrates the importance of epidemiological history, repeated urine microscopy, and recognition of characteristic cystoscopic findings when evaluating bladder masses in patients from endemic regions.
Abstract The family Brachycladiidae is the most species-rich trematode taxon restricted to marine mammals, with several species being highly pathogenic. The biology of the brachycladiids remains poorly understood due to confused systematics, scarce genetic data, and unknown circulation pathways. All these challenges collide in the case of Campula oblonga Cobbold, 1858, a widespread parasite of porpoises with an unknown life cycle and signs of genetic and morphological heterogeneity across its range. To resolve this putative species complex, we sampled naticid gastropods in the Barents Sea and searched for potential brachycladiid intramolluscan stages. Several Cryptonatica affinis (Gmelin, 1791) moonsnails harboured rediae and ocellate cercariae whose nuclear (18S, 28S rDNA) and mitochondrial (nad3 mtDNA) sequences confirmed that they belong to C. oblonga. This finding represents the first unambiguous identification of an intermediate host for a trematode parasite restricted to cetaceans. Combining these life-cycle data with available genetic, morphological, and distribution records, following an integrative taxonomic approach, we hypothesised that C. oblonga may comprise three lineages: C. oblonga (to which the newly discovered intramolluscan stages belong), C. folium Ozaki, 1935, and an undescribed species, Campula sp. NWP1.
Abstract Anacanthorus is one of the most diverse genera of monopisthocotyl parasites associated with Neotropical Characiformes, particularly serrasalmid fishes. This study aimed to inventory the monopisthocotyl parasites of serrasalmid fish from the Lower São Francisco River, northeastern Brazil. Twenty-nine specimens of Pygocentrus nattereri were collected, and their parasites were examined using standard morphological methods. Our results allowed the description of Anacanthorus penedensis n. sp., supported by morphological and molecular data, and the assessment of its phylogenetic relationships within the Dactylogyridae using partial 28S rDNA sequences. Additionally, previously described monopisthocotyls are reported, including Anacanthorus reginae, Amphithecium falcatum, and Enallothecium aegidatum, whereas Rhinoxenus sp. was identified to the genus level and another dactylogyrid remained unidentified. Anacanthorus penedensis n. sp. can be distinguished from its congeners by having an accessory piece comprising two distinct expansions: a submedial expansion extending to the distal region and a conspicuous laminar subterminal expansion originating from one of the margins of the shaft, with a hooked acute tip, as well as by the relative lengths of the male copulatory organ and the accessory piece. Phylogenetic analyses of 28S rDNA sequences, based on maximum likelihood and Bayesian inference, placed the new species within the genus Anacanthorus and supported the monophyly of the group based on the dataset used in the present study. These findings reinforce the need for future integrative taxonomic studies that combine complementary lines of evidence for species delimitation and suggest the diversity of Anacanthorus remains underestimated.
Abstract As part of a broader survey on entomopathogenic nematodes (EPN), two species, Steinernema carpocapsae and S. thesami , were found for the first time in Serbia at Mt Avala. Two populations of S. carpocapsae (AV10 and AV27) were characterised using morphological and molecular methods. Sequencing of the ITS rDNA region confirmed both isolates as S. carpocapsae . Morphometric examination of infective juveniles and first- and second-generation males revealed generally typical characteristics of S. carpocapsae , although notable intraspecific variation was observed. A comparison of morphometric characters among described S. carpocapsae populations available in the literature is provided. Bacteria associated with the nematode populations were isolated from infected Galleria mellonella larvae and identified by sequencing the 16S rRNA and rpoB genes as Xenorhabdus nematophila , Serratia marcescens , Stenotrophomonas maltophilia , Enterococcus casseliflavus , Bacillus cereus , B. paranthracis , and Priestia megaterium . Pathogenicity bioassays showed that oral administration of bacterial suspensions did not cause mortality in G. mellonella larvae, whereas direct injection into the haemocoel resulted in significant mortality for most isolates. The results expand knowledge of the morphological diversity of S. carpocapsae , pointing out some possible causes that may affect intraspecific variability and providing evidence that several members of the nematode-associated microbiota possess entomopathogenic potential when intrahemocoelically administered.
