Parasitology Research最新文献

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.

The immunomodulatory activity of parasites has been extensively investigated in multiple immune-related diseases. However, dermatological diseases have been off the list for a long time despite their vast incidence and the deleterious consequences of some of them. This study explored the immunomodulatory role of autoclaved Trichinella spiralis (T. spiralis) larvae antigen (ATSLA) as a psoriasis immunotherapeutic candidate in a mice model. Psoriasis was induced in Swiss albino mice using commercial imiquimod cream (IMQ). Mice were randomly divided into the IMQ untreated control group and the IMQ treated group that was treated with ATSLA twice, on day 0 and day 3. Additional mice served as normal controls. Assessment of skin thickness, erythema, and scales was recorded. Total skin scores were calculated. Skin MDA levels, splenic indices, serum and skin IL-23, and tumor necrosis factor alpha (TNF-α) were measured. Skin sections were stained with H&E and immune stained for CD68-positive cells using immunohistochemistry. Treatment with ATSLA significantly reduced skin thickness, erythema, scales, and total skin scores in the IMQ-treated group compared to the untreated control. This was accompanied by a reduction in the splenic index, skin MDA levels, IL-23, and TNF-α in both the skin and serum of the treated group. Pathologically, skin sections of the treated group showed less epidermal thickness, acanthosis, hyperkeratosis, and CD68 cell count. The study concluded the immunotherapeutic activity of ATSLA in experimental psoriatic skin lesions. This will enrich the psoriasis immunotherapeutic list with novel candidates of parasitic origin.

Sparganosis is a parasitic zoonotic disease that poses a serious threat to public hygiene and human health. Annexin is a phospholipid-binding protein with calcium ion binding activity, serving various important functions, including interaction with the parasite and regulation of the host's immune response. In this study, two annexin (ANX) family genes, Spirometra erinaceieuropaei (S. erinaceieuropaei) Annexin B8 (SeANXB8) and E1 (SeANXE1), isolated from spargana, were cloned and immunologically characterized. Both recombinant S. erinaceieuropaei Annexin B8 (rSeANXB8) and E1 (rSeANXE1) were specifically recognized by serum from rats immunized with the recombinant proteins, displaying strong immunoreactivity. They are also among the major components of sparganum excretion/secretion products (ESPs). SeANXE1 was identified in the parasite's tegument, testis, genital pore, ovary, and eggs, while SeANXB8 was found in the parasite's tegument and eggs. Plasminogen (PLG)-binding assays revealed that the two annexins could bind to human PLG in a concentration-dependent manner, which was blocked by the corresponding antibodies. These findings suggest that SeANXB8 and SeANXE1 may be involved in host-parasite interaction and may influence the host's immune response during sparganosis. They could be potential diagnosis and vaccination targets for sparganosis.

Yellow grub disease is a parasite infection, caused by Clinostomum spp. Metacercariae and affecting axial muscles and internal organs of freshwater fish. Killifishes live in seasonal ponds and are short-lived; in the Neotropical region they are among the most vulnerable vertebrates. The current study analyzes the possible injury and inflammatory reaction caused by parasitic infection with Clinostomum spp. metacercariae in testes, ovaries, liver, intestine and mesentery in the seasonal killifishes Trigonectes aplocheiloides and Titanolebias monstrosus. Apparently, this parasite could migrate through the circulatory system to different organs, since a cercaria was found in the lumen of a hepatic sinusoid. In all organs the inflammatory response showed dilated, congested vascular areas and infiltration of numerous inflammatory cells, mainly composed of lymphocytes, eosinophilic granular cells and macrophages. However, the most affected organs were the pancreas, ovaries and testes. In these organs, severe pancreatitis with degranulation of the pancreatic acini, scarce ovarian follicles and spermatocysts dilated with few or no seminiferous cells were observed. In seasonal killifish, yellow grub disease could cause low fertility rates or even sterility by reducing or impairing their reproductive capacity. Therefore, this type of parasitism has a considerable impact on the perpetuation of this species due to the short periods they have to breed before their habitats dry out.

A species set in a site comprises species that are present (realized diversity) and species that could inhabit this site but are absent (dark diversity; DD). DD can be both species-driven (a species' traits preclude its presence, independently of site features) and site-driven (site features preclude the species' presence, independently of its traits). DD affinity (DDA) is a measure of species' tendencies to be absent from sites that they could inhabit or of sites' tendencies to lack species that could be present. Decomposition of DDA into DDA for species (dda_sp) and for sites (dda_site) allows (a) disentangling these two mechanisms and (b) detecting species traits and site features contributing to their DDA. The species-site unified model is a Bayesian statistical model aimed at simultaneously estimating dda_sp and dda_site. We applied it to flea and mite assemblages (a) within a host species across regions (component metacommunities; CtM; dda_site = dda_region) and (b) within a region across host species (compound metacommunities; CdM, dda_site = dda_host). In CtMs, dda_sp and dda_region equally contributed to DD, whereas the relative contributions of dda_sp and dda_host to DD in CdMs varied from the former being higher than the latter and vice versa. In CtM and CdM, dda_sp increased in low-abundance ectoparasites exploiting a restricted number of hosts. In CtMs, dda_region was associated with the regional environment, but we failed to find host traits affecting dda_host in CdMs. We conclude that ectoparasite species and either regions in CtMs or host species in CdMs independently contribute to DD.

The life-cycle of Amblyomma calcaratum was evaluated experimentally under laboratory conditions using birds (Serinus canaria, Gallus gallus) and rodents (Calomys callosus) as hosts for immatures and a rabbit (Oryctolagus cuniculus) as host for adults. Developmental periods of the non-parasitic stages were observed in an incubator at 27 °C and 90% RH. The passerine S. canaria was the most suitable host for larvae and nymphs whereas the rodent C. callosus was not suitable to both immatures; only one engorged larva was recovered. The suitability of S. canaria for larvae and nymphs of A. calcaratum supports field data regarding passerine birds as main hosts for A. calcaratum immatures. Among the Amblyomma species which life cycle has been evaluated under laboratory conditions, A. calcaratum is one with the longest off-host developmental periods.