Parasitology International最新文献

Cutaneous leishmaniasis (CL) is a neglected tropical disease associated with significant morbidity, primarily due to chronic skin lesions, scarring, and psychosocial consequences. This study aimed to investigate the in vitro and ex vivo antileishmanial effects of thymol (1-500 μM) against Leishmania tropica (MHOM/TR/2012/CBCL-LT) infection. Thymol's in vitro efficacy was assessed on both promastigote (Haemocytometry and CellTiter-Glo assays) and amastigote (Giemsa staining and Parasite Rescue Transformation Assay) forms of L. tropica. Additionally, its immunomodulatory effects were evaluated by analyzing cytokine secretion (IFN-γ, IL-12, IL-10, and IL-4) and infectivity in THP-1 macrophages using ELISA. Cytotoxicity was determined by calculating the 50 % cytotoxic concentration (CC₅₀) in THP-1 cells. The in vitro inhibitory concentration (IC₅₀) value against L. tropica promastigotes was determined as 79.41 μM, while the ex vivo IC₅₀ value against amastigotes was 105.2 μM. Incubation of infected macrophages with thymol resulted in a dose-dependent increase in IFN-γ and IL-12 levels, along with a significant reduction in IL-10 and IL-4 secretion (p < 0.05). The CC₅₀ value of thymol in THP-1 cells was 160.7 μM, indicating low cytotoxicity. Moreover, the selectivity index (SI) values greater than 1 confirmed the compound's preferential action against amastigotes while exhibiting minimal toxicity toward macrophages. These findings highlight thymol's potential as an antileishmanial agent by effectively eliminating and controlling Leishmania parasites in both in vitro and ex vivo models. Due to its immunomodulatory properties and low cytotoxicity, thymol represents a promising starting point for the development of novel antileishmanial agents and alternative therapeutic strategies against CL caused by L. tropica.

Sika deer, primarily animals of Japanese origin, have been introduced into Europe and, following release into the wild, established free-ranging populations in several countries, including Germany. In addition to the wild populations, sika deer are still maintained in deer parks and there are also deer farms carrying sika deer for venison production. However, to date there is no information about the parasite fauna that infect farmed sika deer and only little knowledge on parasites of sika deer in parks. This work summarizes the results of the examination for endoparasites of viscera and muscle samples of 33 sika deer from five farms and 11 sika deer from five parks in Germany. Eight species of nematodes (Ostertagia leptospicularis, Spiculopteragia asymmetrica, Spiculopteragia boehmi, Spiculopteragia houdemeri, Trichostrongylus askivali, Oesophagostomum sikae, Oesophagostomum venulosum, Trichuris globulosa) and one species of coccidia (Eimeria austriaca) were isolated from the gastrointestinal tract. Sarcocystis cysts were identified in cardiac and/or diaphragm myocytes of 6/11 park deer while no cysts were detected in heart and/or diaphragm samples from 24 farmed deer. No cestodes, lungworms, liver flukes and rumen flukes were found. The nematode community was dominated by the polymorphic ostertagids residing in the abomasum, but the total burden (adults plus mucosal larval stages) was overall very low with geometric mean counts of 62 and 117 in the farmed deer (range, 0 to 2340) and park deer (range, 26 to 629), respectively. Spiculopteragia houdemeri, index ostertagid of sika deer of Japanese origin, made more than 80 % of the total nematode burden in both farmed and park sika deer.

Opisthorchis viverrini (Ov) infection is a major public health concern in the Greater Mekong Subregion, with cats as key reservoir hosts. Although machine learning (ML) is widely used in human medicine, its application in veterinary epidemiology remains limited. This study aimed to develop interpretable ML models to predict Ov infection and to identify key risk factors in cats using data from 175 households in endemic areas. Five ML algorithms-Classification Tree, Random Forest, Ridge Logistic Regression (Ridge LR), eXtreme Gradient Boosting, and Support Vector Machine (SVM)-were optimized using feature selection methods, hyperparameter tuning, and SMOTE. The results demonstrated that Ridge LR with Minimum Redundancy Maximum Relevance (mRMR), tuned Ridge LR, and tuned SVM achieved reliable performance, with ROC-AUC values exceeding 0.7. Specifically, default Ridge LR with mRMR achieved strong balanced accuracy (0.722), while tuned Ridge LR attained the highest sensitivity (0.667). Tuned SVM with mRMR yielded a test ROC-AUC of 0.723 and PR-AUC of 0.473, along with a balanced accuracy of 0.682. SHapley Additive exPlanations (SHAP) analysis identified key risk factors, including residence in flooded areas, feeding fish scraps to cats, and annual rainfall, emphasizing the role of environmental factors in Ov transmission. These findings highlight the potential of ML in veterinary epidemiology and emphasize the importance of selecting appropriate methods based on data characteristics. The study suggests that targeted, risk-based interventions focusing on these key risk factors are crucial for effective Ov control in endemic regions.

Toxoplasmosis, a parasitic infection caused by Toxoplasma gondii, is widely distributed worldwide. Although it generally remains asymptomatic in immunocompetent individuals, it can lead to severe complications in immunocompromised patients, particularly those infected with HIV. These individuals are at increased risk of developing encephalitis, primarily due to the reactivation of a latent infection. Genotyping of T. gondii in humans is an essential tool for studying the epidemiology of this parasitosis. Previous studies have identified three main archetypal (classical) lineages or genotypes: type I, II, and III, as well as strains that show distinct and broader genetic variations. In this study, we report for the first time in Algeria the isolation and genetic characterization of the Africa 4 lineage of Toxoplasma gondii using microsatellites genotyping in an HIV-positive patient. This recently described clonal lineage in animal highlights the genetic diversity of T. gondii now reported in human. This work underscores the need for studies to explore the prevalence and distribution of genotypes in the Maghreb region.

Rodents serve as reservoir hosts for many parasites, including the closely related intracellular protozoan parasites Toxoplasma gondii and Neospora caninum, which are regarded as major causes of abortion in ruminants. This study investigated T. gondii and N. caninum infections in synanthropic (Muridae) and wild (Cricetidae) rodents from rural areas in the Pampas Region, Argentina, using histological, serological, and molecular methods. We also genetically characterized T. gondii isolates. A total of 356 rodents were captured, comprising both murid (Mus musculus, Rattus norvegicus, R. rattus) and cricetid (Oxymycterus rufus, Necromys spp., Akodon azarae, Oligoryzomys flavescens, Calomys musculinus, C. laucha) species. Histological examination did not reveal tissue cysts of these parasites. However, antibodies for T. gondii and N. caninum were detected in 9.8 % (35/356) and 1.7 % (6/356) of the samples using the indirect immunofluorescent antibody test (IFAT). T. gondii DNA was detected by qPCR in brain samples from two of the 41 seropositive rodents. Multilocus PCR-RFLP revealed atypical T. gondii genotypes in both samples. N. caninum DNA was not detected by PCR in any sample. This study provides the first serological and molecular evidence of T. gondii and N. caninum in Cricetidae rodents from Argentina, including the first genotyping data. The detection of T. gondii DNA exclusively in wild rodents highlights the role of wildlife in parasite transmission.

Among parasites with vertebrate hosts, myxozoans (Cnidaria) remain some of the least studied both taxonomically and geographically. We conducted the first reported surveys for myxozoans from amphibian hosts in Ecuador at two localities: a mid-elevation cloud forest on the Chocó region (western slopes of the Andes) and a lowland Amazonian tropical forest, east of the Andes. We sampled 177 gall bladders and 17 kidneys across the surveys. We found no evidence of myxozoans in the cloud forest site. Myxozoans of the genus Cystodiscus were encountered in the gallbladders of multiple amphibian species from the Amazonian rainforest site, including new host records. Our molecular phylogenies show that, while many of these myxozoans were referable to a clade of C. cf. immersus, we also discovered a divergent lineage of Cystodiscus in the gall bladder of a host that, unlike other known amphibian hosts, has arboreal oviposition. We describe this lineage as a new species, Cystodiscus insperatus n. sp., and infer transmission scenarios consistent with the unique ecology of its frog host. We also report for the first time molecular evidence of a possible new lineage of Sphaerospora living in the kidneys of Osteocephalus taurinus (Anura). Collectively, our study highlights the potential for (i) large biogeographic barriers (like the Andes) to influence the distribution of myxozoans and (ii) intermediate host ecology to drive the evolution of novel lineages of these parasites.