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Strongyloidosis is a parasitic disease caused by Strongyloides stercoralis, a nematode with a complex life cycle that facilitates long-term persistence within the host. The infection affects millions of people in tropical and subtropical regions and poses a particular challenge in immunocompromised individuals. Although conventional treatments, such as ivermectin and albendazole, are generally effective, emerging concerns regarding drug resistance and adverse effects have prompted the search for alternative therapeutic options. In this context, natural products—including plant extracts, bioactive phytochemicals, and nanoparticle-based formulations derived from natural sources—are emerging as promising anti-Strongyloides potential. This review summarizes recent studies on natural products with anthelmintic activity against strongyloidiasis, with emphasis on their mechanisms of action, efficacy, and future perspectives. A systematic search of the literature was conducted using terms related to Strongyloides, plant species, extracts, and bioactive compounds with nematocidal activity. Eligible studies included those reporting the activity of plants, plant extracts, and their purified metabolites against Strongyloides spp. Data were compiled into a comprehensive table including year of publication, author, plant species, active principle, application conditions, and target nematode species. The pharmacological treatment of this parasite varies according to its life cycle stage. Various biomolecules, phytoactive compounds, and novel plant-based formulations have demonstrated promising activity and may be considered both for treatment and for inclusion in control programs for strongyloidiasis. This review highlights medicinal plants and phytochemicals with ethnopharmacological background and experimentally validated activity against Strongyloides spp., integrating evidence from in vitro, in vivo, and experimental models, as well as clinical trials.

The effects of condensed tannins (CTs) extracted from pine bark on egg hatching, larval development and the viability of infective L3 larvae of Trichostrongylus colubriformis and Teladorsagia circumcincta (syn. Ostertagia circumcincta) were evaluated using in vitro bioassays. Significant inhibitory effects of CTs were obtained on the viability of the infective larvae, egg hatching and larval development of both nematodes. In all bioassays, the larval stages of Te. circumcincta were significantly (P less than 0.05) more susceptible to the inhibitory effects of CT than those of Tr. colubriformis. At 1 000 microg/ml, CTs from pine bark inhibited 48% and 69% of the infective larvae of Tr. colubriformis and Te. circumcincta, respectively, from passing through the sieve relative to the control incubations (no CT added; P less than 0.0001). At the same concentration, CTs were able to inhibit 36% and 47% of the eggs of the two parasites, respectively, from hatching relative to the control incubations without CTs. Moreover, at 150 microg/ml, the CTs were able to inhibit 88% and 95% (P less than 0.0001 relative to control incubation) of L1 larvae of the two nematodes, respectively, from attaining the full development to L3 larvae in comparison with the control incubations without CTs. At 200 microg/ml, CTs were able to inhibit completely the larval development in both nematodes. Addition of 2 microg polyethylene glycol (PEG; tannin inhibitor) per microg CT eliminated up to 87% of the CT activity (P less than 0.0001) compared to incubations without PEG. In conclusion, this study shows that CTs are able to disrupt the life cycle of nematodes and their effects varied according to the parasite species and stage.

Based on light and scanning electron microscopical studies, the following nine species of Philometridae (Nematoda: Dracunculoidea) are described from female worms parasitizing marine perciform fishes belonging to six families off the northern coast Australia (near Darwin): Philometra australiensis sp. n. from the swimbladder of the king threadfin Polydactylus macrochir (Polynemidae); P. epinepheli from the operculum of the orange-spotted grouper Epinephelus coioides (Serranidae); Philometra johnii from the gonad of the croaker Johnius sp. (Sciaenidae); P. macrochiri sp. n. from the sensory fin of P. macrochir; P. zabidii sp. n. from the ovary of the ninespine batfish Zabidius novemaculeatus (Ephippidae); Philometra sp. 1 and Philometra sp. 2 from the ovary of the Spanish flag snapper Lutjanus carponotatus (Lutjanidae) and the silver grunt Pomadasys argenteus (Haemulidae), respectively; Philometroides eleutheronemae from the ovary of the fourfinger threadfin Eleutheronema tetradactylum (Polynemidae); and Spirophilometra endangae from the pectoral fins of E. coioides. The new species P. australiensis is characterized mainly by the structure of the cephalic end, 14 minute cephalic papillae, absence of caudal projections and body length of gravid female (67 mm), P. macrochiri by the presence of a conspicuously large anterior oesophageal bulb, 14 very small cephalic papillae and the truncated posterior end of body without any caudal projections, whereas P. zabidii is characterized by the presence of distinct caudal projections, the number (14) and larger size and arrangement of cephalic papillae, a poorly developed anterior oesophageal inflation, the body length (114 mm) and the host family (Ephippidae). All above-mentioned species were recorded from Australian waters for the first time.

A new capillariid nematode, Capillostrongyloides morae sp. n., is described from specimens collected from the stomach and intestine of the common mora, Mora moro, and the Mediterranean codling, Lepidion lepidion (both Gadiformes, Moridae), off the Mediterranean coasts of Spain. The new species shows similar morphological features as other congeneric species occurring in freshwater and marine fishes, but it differs in the length of the body and spicules, the size of the caudal bursa, and the presence of an elevated anterior vulvar lip. Capillostrongyloides morae sp. n. is the second species within the genus for which the presence of a stylet is reported, and the first one in which this structure along with the distribution of cephalic papillae and oral structures (e.g. lips and lobes) are clearly shown by using scanning electron microscopy.

A new nematode species, Comephoronema multipapillatum sp. n. (Cystidicolidae), is described from the anterior intestine and caecum of the squirrelfish Holocentrus adscensionis (Beryciformes: Holocentridae) collected in Angra dos Reis, State of Rio de Janeiro, offshore Brazil. The new species was placed in Comephoronema by having an oval oral aperture, four submedian labia, four bilobed submedian sublabia, two narrow lateral pseudolabia and four single cephalic papillae, but mainly by numerous precloacal papillae in males (more than six pairs), in which it differs from species of the otherwise morphologically similar genus Ascarophis. Comephoronema multipapillatum sp. n. can be easily distinguished from other congeners based on the high number of precloacal papillae in males (18 pairs + one unpaired) and also by the bidentate plate structure on the inner margin of pseudolabia, mature eggs with two long filaments on a single pole, body length of male (9.4-11.5 mm) and female (10.2-19.9 mm), left spicule size (222-278 microm) and length ratio of spicules (1 : 2.2-2.8). This is the fifth nominal species of Comephoronema, the first nematode registered parasitizing H. adscensionis and the first species of the genus in the Neotropical part of the Atlantic Ocean.

Parasitic helminths typically induce components of immediate-type hypersensitivity, including elevated serum IgE, eosinophilia, and mucosal mast cells. These responses are T-cell-dependent and associated with rapid expulsion of parasitic worms from a sensitized host; existing experimental systems have failed to define the precise role of cytokines in these responses. We report here that anti-interleukin 4 or anti-interleukin 4 receptor antibodies block the polyclonal IgE response to a parasitic nematode, Heligmosomoides polygyrus, and abrogate protective immunity to the infection. In contrast, anti-interleukin 5 antibody prevented H. polygyrus-induced eosinophilia but did not prevent protection. These data provide evidence that a specific cytokine affects the physiology and survival of a parasitic nematode in the host.

Using data on 66 species from 18 families and 6 orders, we examine patterns of interspecific covariation in female size, egg size, time from infection to production of infective stages (prepatency period), duration of reproduction (patency period), and fecundity in mammalian intestinal nematodes. Nematode species with shorter prepatency periods are smaller, have lower rates of somatic growth, lower fecundity and shorter reproductive periods; those with longer prepatency periods have the opposite suite of characters. These patterns are very different from that found in interspecific analyses of life history variation in other taxa. This may be a consequence of the energy-rich environment intestinal nematodes exploit, though comparable studies of free-living nematodes or other soft-bodies invertebrate phyla have not yet been done. The advantages of delaying reproduction, with the subsequent increase in fecundity and reproductive lifespan, depend on a number of factors, such as the relative importance of prepatency in the determination of parasite generation times, and adult mortality rates. Contrary to previous claims, nematode egg size is shown to be highly variable (as variable as female size), yet this variation is not associated with any other component of reproductive rate. This may be because of interspecific variation in egg shell thickness and complexity.

It was previously shown that the Haemonchus contortus apical gut surface proteins p46, p52, and p100 induced protective immunity to challenge infections in goats. Here, it is shown that the three proteins are all encoded by a single gene (GA1) and initially expressed in adult parasites as a polyprotein (p100GA1). p46GA1 and p52GA1 are related proteins with 47% sequence identity, including a cysteine-containing region, which appears to confer secondary structure to these proteins, and a region with sequence similarity to bacterial Tolb proteins. GA1 protein expression is regulated during the life cycle at the level of transcript abundance. Only p52GA1 has characteristics of a glycosylinositolphospholipid membrane-anchored protein. However, both p46GA1 and p52GA1 were released from the gut membrane by phosphatidylinositol specific-phospholipase C, suggesting that p46GA1 membrane association depends on interactions with a glycosylinositolphospholipid gut membrane protein. Finally, GA1 proteins occur in abomasal mucus of infected lambs, demonstrating possible presentation to the host immune system during H. contortus infection. The results identify multiple characteristics of the GA1 proteins that should be considered for design of recombinant antigens for vaccine trials and that implicate a series of cellular processes leading to modification and expression of GA1 proteins at the nematode apical gut surface.

Antibody response to Syphacia obvelata infection was observed in AKR/J mice by ELISA. Experimental infection with the pinworm eggs showed the presence of specific IgG against S. obvelata somatic antigens at 12 days postinfection, and that it increased steadily thereafter. Sera of S. obvelata-infected mice showed cross-reactivity with somatic antigens of other Syphacia species such as S. mesocriceti and S. muris, but not with Aspiculuris asiatica. Western blotting of S. obvelata antigen with sera of S. obvelata-infected mice showed a corresponding increase in the number of bands during the course of infection. Infected mice showed significantly higher antibody production to sheep red blood cells than the uninfected control mice. Thus, S. obvelata infection is shown to alter the humoral response to nonparasitic antigenic stimuli. These observations indicate that infection by helminths, which apparently do not produce clinical symptoms, might modulate the immune system of the host and, therefore, affect experimental results.

Libyostrongylus dentatus sp. n. is described from ostriches on farms from North Carolina and Texas. Nematodes were recovered from the posterior proventriculus and under the koilon lining of the gizzard; the parasites occurred in mixed infections with Libyostrongylus douglassii. The species is distinguished from congeners by the presence of a prominent, dorsal, esophageal tooth; in males by the structure of the dorsal ray and spicules; and in females by small eggs (52-62 µm in length), a sublateral vulva situated at 93% of the body length from the anterior, and a strongly curled, digitate, tail with cuticular inflations at the anus. Conflicts in the generic diagnoses of Libyostrongylus and Paralibyostrongylus were apparent, based on the structure of the dorsal ray or position of rays 3-5 of the copulatory bursa. These can only be resolved based on phylogenetic analyses of the 11 nominal species referred to these genera.