Parasitology Research最新文献

The current study was focused on evaluating the in vitro effect of the spore-crystal complex of GP543 Bacillus thuringiensis strain on the viability of Amblyomma cajennense, and the in vivo reduction of the parasite load of this ectoparasite on naturally infested cattle. In vitro, 30 adult ticks were treated with 1.2 mg/ml of B. thuringiensis GP543 strain spore-crystal complex in 10 µl/ml of AGREX F® surfactant and 20% glycerin, subjected to the immersion test to assess their viability every 1.5 h up to 6 h and finally at 12 h post-immersion. GP543 was compared to 125 µg/ml of the commercial drug BOMBARD® (amitraz). In vivo, the same concentrations were tested on naturally infested Swiss-Zebu heifers in grazing conditions. Treatments were applied on the perineal region in an area of 30 × 15 cm on days 0 and 7, and the parasite load was determined on days 0, 3, 7, 9, 14, and 21. In vitro, GP543 decreased the viability rate a 96.6% at 12 h post-immersion, while the commercial drug induced a 100% decrease of viability. On heifers, the parasite load decreased after 21 days in the group treated with GP543 in a similar way to the group treated with amitraz. Considering the above, GP543 strain of B. thuringiensis is proposed as a candidate for the control of Amblyomma cajennense.

Piroplasmids are vector-borne hemoprotozoan parasites belonging to the phylum Apicomplexa that are of veterinary and medical importance. Wild carnivores are hosts for diverse piroplasmids, some of which are highly pathogenic for domestic dogs and cats. A large-scale survey including samples from 244 individuals belonging to eleven different species that were opportunistically obtained between 1993 and 2015 in four Autonomous Regions in Spain were tested for piroplasmid DNA with two different nested-PCR assays targeting the 18S rRNA gene. Sixty of 85 Eurasian badgers (Meles meles), 11 of 42 red foxes (Vulpes vulpes), and 1 of 10 stone martens (Martes foina) resulted positive. In contrast, 46 wolves (Canis lupus), 26 genets (Genetta genetta), 22 pine martens (Martes martes), and other less-represented species were negative. Sequencing revealed that all foxes and one badger were parasitized by Babesia vulpes, and the remaining badgers and the stone marten by Babesia sp. badger type A (BBTA). The prevalence of BBTA in Catalonian badgers was significantly lower in Alpine than in Continental and Mediterranean climates. This study confirms that badgers and ref foxes constitute the natural hosts of BBTA and B. vulpes, respectively, with occasional spillovers to other species.

There is a growing number of reports on the occurrence of benzimidazole resistance-associated single nucleotide polymorphisms (SNPs) in the β-tubulin isotype 1 gene of various helminths of veterinary, and public health concerns. However, a comprehensive analysis of their occurrence, and their contributions to conferring benzimidazole resistance among hookworms has yet to be done. The objectives of this systematic review are to summarize and synthesize peer-reviewed evidence on the occurrence of these resistance-associated mutations in hookworms, document their geographical distribution, and assess their contributions to conferring phenotypic resistance. Three databases were systematically searched using specific keywords. Research that assessed the occurrence of benzimidazole resistance-associated SNPs in hookworms, papers that reported the geographical distribution of these SNPs, and studies that investigated the SNPs' resistance-associated phenotypic effects were included in the review. Research that was not done in hookworms, papers not in the English language, and literature reviews and book chapters were excluded. Critical appraisal checklists were used to determine the risk of bias in the selected papers. Data were extracted from the selected studies and analyzed. PROSPERO Systematic Review Protocol Registration No.: CRD42024510924. A total of 29 studies were included and analyzed. Of these, four were conducted in a laboratory setting, eight described the development and validation of SNP detection methods, and the remaining 17 involved field research. Seven SNP-induced amino acid substitutions at four loci were reported among several hookworm species: Q134H, F167Y, E198A, E198K, E198V, F200Y, and F200L. SNPs have been reported in isolates occurring in the United States, Canada, Brazil, Haiti, Australia, New Zealand, Kenya, Ghana, Mozambique, and Tanzania. Resistance mutations have not been reported in Asia. E198A and F200L were reported in Ancylostoma ceylanicum with laboratory-induced resistance. F167Y and Q134H conferred resistance in A. caninum, as revealed by in vitro investigations and field assessments. There is insufficient peer-reviewed evidence to prove the association between SNP occurrence and resistance. Mutations in the β-tubulin isotype 1 gene confer benzimidazole resistance in A. caninum and A. ceylanicum, but similar evidence is lacking for other human hookworms. Understanding benzimidazole resistance through further research can better inform treatment, prevention, and control strategies.

The mitochondrial permeability transition pore (mPTP) significantly impacts mitochondrial responses to cell death signals through its structural opening. Cyclophilin D (CypD) serves as a key regulator of the mPTP and plays a pivotal role in governing mitochondrial responses to cell death. In this study, we have demonstrated that Toxoplasma expresses a homolog of cyclophilin D, named TgCypD, which is localized in the mitochondria. Depletion of TgCypD resulted in a modest inhibition of tachyzoite invasion and proliferation, with no notable effect on mitochondrial morphology. However, TgCypD deficiency led to the inhibition of cytochrome c release from mitochondria into the cytosol, thereby imparting resistance to oxidative stress-induced cell death. Our findings suggest that T. gondii contains the mPTP component protein TgCypD, which is intricately involved in regulating mitochondrial responses to cell death.

Invasive alien species have the potential to introduce pathogens of economic and health importance in new environments. In Brazil, parasites from the non-native European brown hare can be a threat to humans, domestic animals, and wildlife. Therefore, we aimed to describe the helminth fauna of the invasive European brown hare in three Brazilian states (São Paulo, Paraná, and Rio Grande do Sul). For this, 90 brown hares were collected and examined for helminths. Helminth specimens recovered were morphologically identified and genetically characterized based on the DNA of male specimens using three genetic regions (28S rDNA, ITS-2, and cox-1 mtDNA). Descriptors of infection were calculated, and statistical analysis was performed. Parasites were found only in the small intestine of 14.4% (13/90) of brown hares and low parasite loads per animal were recorded (range = 1-530). The obtained specimens were morphologically identified as Trichostrongylus colubriformis and Bunostomum trigonocephalum. There was a high level of agreement between phylogenetic analysis and morphology for T. colubriformis. The geographical region was the only significant factor for infection; the State of Rio Grande do Sul had a higher general prevalence, higher T. colubriformis specific prevalence, and higher mean abundance than the other states evaluated. All hares were in a good body condition. To our knowledge, this is a new host record for B. trigonocephalum. This is the first study on the helminthological diversity of European brown hares in Brazil, and our results indicate that their helminth fauna is represented by parasites of domestic ruminants with zoonotic potential.

Despite the long history of experimental trials to combat schistosomiasis, it remains a significant burden due to drug resistance and the effectiveness of the standard treatment only against the mature stage, while skipping other early developmental stages thus leading to severe permanent pathological sequelae. Therefore, repurposing a commonly used well-known safe drug would be a wise alternative. We investigated the potential anti-schistosomal drug activity of Daflon® (DAF) against different schistosomal developmental stages. DAF was administrated at a dose of 100 mg/kg/mouse on days zero, 21, and 42 post-infection towards the invasive, immature, and mature stages of Schistosoma mansoni respectively in comparison to the standard anti-schistosomal drug (Praziquantel). All mice were sacrificed on day 49 post-infection. DAF induced a significant reduction in the total and female worm count, hepatic granuloma size, and number, the extent of liver parenchymal injury and fibrosis as well as intestinal and hepatic egg count compared to the infected untreated control. Liver malondialdehyde (MDA) levels significantly decreased in all DAF-treated groups. Scanning electron microscope findings revealed edema, tegumental blebs, cracks, and fissures in male tegument in all DAF-treated groups with distortion of the ventral suckers and disarrangement of the spines of the oral sucker. The female worm from DAF-treated groups showed tegumental edema with loss of the spines at the posterior end. Compared to the documented reduction of testosterone levels and distortion of testicular architecture in the S. mansoni-infected untreated group, DAF significantly restored testosterone levels and testicular architecture.

Acanthamoeba species are responsible for serious human infections, including Acanthamoeba keratitis (AK) and granulomatous amoebic encephalitis (GAE). These pathogens have a simple life cycle consisting of an infective trophozoite stage and a resistant cyst stage, with cysts posing significant treatment challenges due to their resilience against harsh conditions and chemical agents. Current treatments for AK often involve combining diamines, such as propamidine, and biguanides, such as chlorhexidine (CLX), which exhibit limited efficacy and significant toxicity. Thus, the effect of new therapeutic molecules, such as multifunctional systems (e.g., carbosilane dendritic molecules), should be studied as potential alternatives due to their biocidal properties and lower toxicity. This study evaluates various dendritic compounds against trophozoites and cysts of two Acanthamoeba clinical isolates, both alone and in combination with CLX, and assesses their cytotoxicity on HeLa cells. The results indicated that certain dendritic compounds, especially BDSQ024, were effective against both trophozoites and cysts. Additionally, combinations of dendritic molecules and CLX showed enhanced efficacy in eliminating trophozoites and cysts, suggesting potential for synergistic treatments. The study underscores the promise of dendritic molecules in developing more effective and less toxic therapies for Acanthamoeba infections.

Antlers are bony structures that undergo regular annual growth, mineralisation and casting phases, representing only mammalian organs capable of full regeneration. Myiasis is infestation of live vertebrates with dipterous larvae. We sampled mineralised antlers from a red deer spiker stag 2 months after velvet shedding, divided it into three segments and fixed in 10% neutral buffered formalin. After demineralisation, samples were embedded in paraffin and sliced to a thickness of 6 µm. Tissue sections were stained with hematoxylin-eosin (HE), a modified staining to show the ossification process, toluidin blue and Masson's trichrome staining. Smears of liquid content from the antlers were made and stained with May-Grünwald Giemsa. Larvae were separated from segments and preserved in 70% ethanol for identification. Macroscopically, some parts of the antler tips were lacking the compact part. Microscopically, within the Haversian and Volkmann canals, a large number of bacteria, scarce protein content and remnants of red blood corpuscles were visible. In the area of cancellous bone, cross-sectioned larvae were present. A large quantity of bacteria and a few degraded red blood corpuscles were visible on the smear made of liquid from the antlers. For morphological identification, three larvae were examined: two were third-instar larvae (L3), while one was a first instar larva (L1). Based on the shape of the cephaloskeleton, L3 was identified as Prochyliza nigrimanus and confirmed using molecular tools. To the extent of the authors' knowledge, this is the first record of Prochyliza nigrimanus in non-casted hard red deer antlers and the first description of this species in Croatia.

Triatoma species from the phyllosoma subcomplex are sympatrically distributed and include some of the main vectors of Chagas disease in Mexico. Species within this subcomplex, including Triatoma pallidipennis, T. mazzottii, T. picturata, and T. longipennis, have shown resistance to pyrethroid insecticides, associated with mutations in the para gene of the voltage gate sodium channel (VGSC) and the activity of detoxifying enzymes such as β-esterases and glutathione s-transferases (GST). In this study, we evaluated resistance to deltamethrin in hybrids of T. pallidipennis × T. mazzottii (T.pal × T.maz) and T. pallidipennis × T. picturata (T.pal × T.pic) under laboratory conditions, and the inheritance was determined based on the degree of dominance (DO). Additionally, associated resistance mechanisms were analyzed, including detoxifying enzymes and knockdown resistance (kdr) mutations. High levels of resistance to deltamethrin were found in the hybrids of T.pal × T.maz when compared with the susceptible strain of T. mazzottii (RR₅₀ = 17.50). Dominance levels calculated for each hybrid showed values <  - 1, confirming that resistance to deltamethrin was recessive. Hybrids exhibited reduced α-, β-esterases, and cytochrome P₄₅₀ mixed-function oxidases (MFO) activity. However, both hybrids showed significantly increased GST activity, particularly in T.pal × T.pic, suggesting enhanced detoxification through this pathway. The kdr mutation A943V, present in T. mazzottii, was found in T.pal × T.maz hybrids. These results emphasize the importance of considering hybridization in resistance management programs and its potential impact on the success of insecticide-based control measures.