This study evaluated, in vitro, the anthelmintic activity of the monoterpene linalool, alone and in association with the fungus Duddingtonia flagrans, against gastrointestinal nematodes of horses. Nematodes from the superfamily Strongyloidea, obtained from naturally infected horses, were used. The ovicidal activity of linalool was evaluated using the Egg Hatch Test (EHT). The larvicidal activity was evaluated using the Larval Motility Inhibition Test (LMIT), in which infective larvae (L3) were assigned to experimental groups treated with linalool alone (0.15, 0.3, 0.6, 1.25, 2.5, 5, 10, 20, 40, and 80 mg/mL), D. flagrans conidia alone (100,000, 500,000, and 1,000,000 conidia), or the combination of both. In the EHT, linalool completely inhibited egg hatching (100%) at all concentrations of 0.25 mg/mL and above, with an LC₅₀ of 0.15 mg/mL (0.015%). In the LMIT, linalool completely inhibited larval motility (100%) at all concentrations of 0.5 mg/mL and above, with an LC₅₀ of 0.103 mg/mL (0.010%). The association with the fungus D. flagrans promoted a significant reduction (p ≤ 0.05) in the number of live larvae after 72 h, reaching 100% inhibition within 14 days. The groups treated only with conidia showed lower efficacy, whereas the association with linalool enhanced the antiparasitic effect without impairing trap formation or the predatory capacity of the fungus. Thus, the results demonstrated that linalool has relevant ovicidal and larvicidal activity, and that its association with D. flagrans constitutes a promising alternative for the biological control of helminth infections in horses.
Urban expansion and environmental fragmentation have intensified contact among wildlife, domestic animals, and humans, reshaping infectious disease dynamics at the human–wildlife interface. Non-human primates (NHP), particularly the black-tufted marmoset (Callithrix penicillata), readily adapt to anthropogenic landscapes and may serve as sentinel hosts for zoonotic pathogens. This study investigated the occurrence of Leishmania spp., Plasmodium spp., Toxoplasma gondii, and Trypanosoma cruzi. in 232 free-ranging C. penicillata found dead in urban and peri-urban areas of the Federal District, central Brazil, between 2018 and 2023. Liver samples were analyzed by quantitative PCR. Plasmodium spp. was not detected (0/232). In contrast, 39.7% (92/232) of marmosets were positive for T. gondii, 32.4% (69/213) for Leishmania spp., and 21.1% (47/223) for T. cruzi. Overall, 71.6% of the animals tested positive for at least one protozoan agent, and 21.2% had coinfections, most commonly Leishmania spp. plus T. gondii. Positive cases were widely distributed across administrative regions, with evidence of spatiotemporal clustering in some urbanized areas. Parasitic loads varied substantially, and most infected animals showed no lesions attributable to these infections. These findings demonstrate the widespread circulation of zoonotic protozoa in free-ranging marmosets inhabiting anthropized environments and reinforce their epidemiological relevance within a One Health framework. Surveillance of urban NHP populations can contribute to understanding transmission networks and environmental contamination, thereby supporting public health strategies for the prevention and control of zoonotic diseases in central Brazil.
The black croaker, Plagioscion auratus, is a fish endemic to South America that is widely exploited commercially in the Amazon basin. In this context, the present study describes a new species of the genus Kudoa infecting the skeletal musculature of P. auratus. The species is described based on morphological characterization and phylogenetic analyses of SSU rDNA sequences. The study was based on the analysis of 48 P. auratus specimens collected off the eastern shore of Jutuba Island, in the eastern Brazilian Amazon region. Elongated pseudocysts were observed within the skeletal muscle fibers, containing varying numbers of pseudoquadrate myxospores measuring 8.2 ± 0.4 (6.9–9.8) μm in length and 13.8 ± 0.3 (12.4–14.9) μm in width, with four equal elongated polar capsules measuring 4.9 ± 0.2 (4.5–5.6) μm in length and 1.9 ± 0.2 (1.7–2.4) μm in width. Histological analysis revealed the development of pseudocysts within muscle fibers and the partial replacement of muscle fibers by connective tissue. Phylogenetic analysis placed Kudoa chromosomatum n. sp. within a clade of Brazilian Amazon species with high nodal support, occupying an early-branching position within the subclade. This is the first Kudoa species described in P. auratus and the second reported from a Brazilian sciaenid host. The distinct morphology of the parasite, together with the molecular data, supports the description of this new species.
The genus Trypanosoma is vulnerable to oxidative stress, and reactive oxygen species (ROS) suppress Trypanosoma proliferation. We investigated the effects of alpha-tocopheryloxyacetic acid (α-TEA), a stable vitamin E-derived mitocan, on the course of Trypanosoma congolense IL-3000 infection in mice and in an in vitro culture. C57BL/6 J male mice infected with 3 × 104 T. congolense IL-3000 cells were fed a 0.25% or 0.75% α-TEA diet for 7 or 28 days from day 3 of infection. The survival duration of all of the α-TEA-treated mice was significantly longer than that of the control mice fed a regular diet (p < 0.05). Similar results were obtained when α-TEA (14 mg/day) was orally administered to mice via a feeding needle 1×/day for 5 days from day 3 after infection; we then observed that α-TEA effectively inhibited the growth of T. congolense in a dose-dependent manner (p < 0.05). To assess the mechanisms of action of α-TEA, we conducted annexin V (AV)/propidium iodide (PI) labeling and a JC-1 labeling lactate assay, plus a 2′,7′-dichlorofluorescein diacetate (DCFH-DA)/mtSOX Deep Red (mtSOX) labeling assay. Treatment with α-TEA induced the apoptosis of T. congolense, decreased the mitochondrial membrane potential (p < 0.05), and produced ROS in mitochondria (p < 0.05). Thus, α-TEA directly suppressed the proliferation of T. congolense in mice by stimulating a mitochondrion of T. congolense to produce ROS. These results indicate that α-TEA might be a potent candidate ingredient for an oral drug to treat the parasitic infection trypanosomiasis, with new mechanisms of action.
