Parasitology Research最新文献

This study investigated the role of host traits, habitat, and sampling season on the prevalence and intensity of parasites in three species of platycephalid fishes. Three host species sampled were dusky flathead (Platycephalus fuscus, n = 3), blue-spotted flathead (Platycephalus caeruleopunctatus, n = 38), and tiger flathead (Platycephalus richardsoni, n = 59). A total of 14 metazoan parasite species were collected over 15 months, between July 2020 and September 2021. The parasites found included a chondracanthid copepod, adult hemiuroidean trematodes, cestode plerocercoids, larval and adult acanthocephalans, larval and adult nematodes, and an unknown species of helminth. General linear models were used to assess the relationship between host traits and sampling season with parasite infection intensity. The infection intensity of an unidentified plerocercoid species in P. caeruleopunctatus was found to be significantly associated with both sampling season and the interaction of host mass with sex. In P. richardsoni the infection intensity of the acanthocephalan, Corynosoma sp. was found to correlate with sampling season. The highest richness of parasite taxa was recorded from P. richardsoni, which may be due to the wide depth range of P. richardsoni, coupled with its generalist diet.

Pentastomida are lung parasites of a variety of hosts, mainly reptiles. Raillietiella is the genus with the largest number of species, whose taxonomic identification is still largely based on morphological data alone. In this classification, differences divide the genus into morphotypic groups. The Raillietiella parasites of insectivorous lizards, for example, are divided into "Group I" with species with hooks with sharp tips and "Group II" with posterior hooks with blunt tips. In the present work, we used molecular analysis to infer the morphological variation in hooks and size of specimens of Raillietiella mottae, parasites of several species of insectivorous lizards. Our results demonstrate that morphological differences comprise a phenotypic plasticity of a single species, whose variation is associated with host species, with females being larger and with hooks with blunt tips in nocturnal geckos and smaller ones with sharp tips in diurnal insectivorous lizards of different species, sizes, and habitats.

This study aimed to investigate the occurrence of larval trematode infections in bithyniid snails across five provinces in southern Thailand. A total of 1,413 Bithynia siamensis snails were collected between October 2021 and October 2022 using handpicking and scooping methods. Among these, 844 were identified as B. s. siamensis and 569 as B. s. goniomphalos. The snail samples were examined for parasitic infections in the laboratory using shedding and crushing methods. Among the 27 sampling sites, snails from 6 sites were infected with various trematode species (infection rate: 4.95%, 70/1,413). Evaluation of the morphological and internal organ characteristics of the cercariae allowed for the categorization of the trematodes into five species of trematodes (belonging to four families). The identified species included Echinochasmus pelecani (family: Echinostomatidae), Echinostoma revolutum (family: Echinostomatidae), Haematoloechus similis (family: Haematoloechidae), Loxogenoides bicolor (family Lecithodendriidae), and Stictodora tridactyla (family: Heterophyidae), and the infection rates for these species were 3.26% (46/1,413), 0.35% (5/1,413), 0.42% (6/1,413), 0.78% (11/1,413), and 0.14% (2/1,413), respectively. The cercariae from the identified trematode species were studied for DNA analysis. The phylogenetic lineage reveals relationships among the species, confirming the morphological distinctions.

Echinococcosis is a zoonotic disease, which seriously endangers human health. The immune game between parasite and host is not fully understood. Exosomes are thought to be one of the ways of information communication between parasite and host. In this study, we attempted to explore the communication between Echinococcus granulosus and its host through the medium of exosomes. We collected plasma from E. granulosus patients (CE-EXO) and healthy donors (HD-EXO) and extracted exosomes from the plasma. The expression profile of miRNA in plasma was determined by second generation sequencing. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) were used to annotate the function of target genes of differential miRNAs. Meanwhile, we co-cultured plasma exosomes from healthy donors and plasma exosomes from E. granulosus patients with Jurkat T cells with or without phytohaemagglutinin (PHA) stimulation. The expression of CD69 on Jurkat T cells was detected by flow cytometry. The results showed that the miRNA of exosomes between healthy donors and E. granulosus patients was significantly different. GO and KEGG were used to annotate the function of target genes of differential miRNAs. The results indicate that many important pathways are involved in inflammation, metabolism, and immune response after parasite infection, such as p53 signaling pathway, PI3K-Akt signaling pathway, and glycolysis/gluconeogenesis. Flow cytometry showed that CE-EXO reduced the expression of CD69 + on Jurkat T cells. Our present results suggest that these differentially expressed miRNAs may be important regulators of parasite-host interactions. Meanwhile, functional prediction of its target genes provides valuable information for understanding the mechanism of host-parasite interactions. These results provide clues for future studies on E. granulosus escape from host immune attack, which could help control E. granulosus infection.

Trichomonas gallinae is a widespread protozoan parasite that primarily affects birds, causing a disease known as avian trichomonosis. The present study aimed to investigate the prevalence and genetic diversity of T. gallinae, a parasite causing avian trichomoniasis in feral pigeons, budgerigars, and finches in Tehran, Iran. The 5.8S ribosomal RNA locus, along with the internal transcribed spacer 2 (ITS2) region, has been extensively utilized for genotype identification and for determining inter- and intra-specific diversity. More recently, the Fe-hydrogenase (Fe-Hyd) gene has been suggested as an additional genetic marker to enhance the accuracy of strain subtyping discrimination. In the present study, a total of 12% (12/100) birds examined were infected with T. gallinae using microscopy and PCR methods. Infection was found in seven of 30 (23.3%) feral pigeons, three of 40 (7.5%) budgerigars, and two of 30 (6.66%) finches. Analysis of the ITS2 region of T. gallinae isolates revealed two highly similar sequences. The first sequence (GenBank: OQ689964-OQ689970) was found in five feral pigeons and two budgerigars, whereas the second sequence (GenBank: OQ689971-OQ689975) was identified in two feral pigeons, one budgerigar, and two finches. Phylogenetic analysis confirmed the presence of two distinct clusters (cluster I and cluster II) within the trichomonads based on the ITS2 region. However, further analysis using Fe-Hyd revealed greater diversity, with three subtypes identified (A1, A2, and C1). One isolate identified in the present study (GenBank accession number: OQ694508.1) belonged to subtype A1. Combining ITS2 and Fe-Hyd markers holds promise for a more comprehensive understanding of the population structure of T. gallinae and the potential role of ITS2 in host adaptation.

An outbreak of Psoroptes sp.-caused mange was detected in a llama herd of Larcas, Jujuy province, Argentina. Infested llamas showed alopecia, erythema, hyperpigmentation, hyperkeratosis, and inflammation of the ear pinnae, as well as crusts and serous, serosanguineous, or purulent drainage with unpleasant smell in the external ear canal. Microscopic evaluation of skin scrapings revealed 0.5- to 0.7-mm-long acari identified as Psoroptes sp. based on their morphology. Histology showed a typical allergic reaction with perivascular to periadnexal mixed inflammatory infiltrate. Phylogenetic tree analysis showed that the cytochrome c oxidase subunit I gene sequences analyzed from the sampled acari clustered into a single P. ovis clade including sequences isolated from rabbits and bighorn sheep, with P. natalensis as a sister taxon that infested bighorn sheep from the USA. Phylogenetic analysis of cytochrome b sequences showed three well-supported clades, one of which contained the sequences of the Larcas llamas and US bighorn sheep isolates. This is the first report on P. ovis infestation of llamas raised in their original location. Investigations on mange etiological agents acting on South American camelids and their distribution are necessary to implement control strategies to mitigate the negative impacts of these parasitic infections.

Urban areas in malaria-endemic countries in East Africa are experiencing a significant increase in malaria cases, with the establishment of an "exotic" urban malaria vector, Anopheles stephensi, increasing the risk of urban malaria. To this end, the present study aimed to investigate the emergence of this species in Arba Minch, Ethiopia. Following the detection of An. stephensi in other parts of Ethiopia, 76 artificial containers (55 discarded tyres, 18 concrete water storage, and three plastic containers) were sampled in 21 locations in Arba Minch town, for immature Anopheles mosquito stages, using the standard dipping technique. Larvae were reared into adults which were morphologically identified at the species level 2-3 days after emergence. Morphological identification results were confirmed by species-specific polymerase chain reaction. Of the examined containers, 67 (88%) had at least one Anopheles larva. Thirty-two of the adults emerged were morphologically identified as An. stephensi, with 26 (81%) confirmed by molecular analysis. This is the first study to report An. stephensi from Arba Minch, one of South Ethiopia's largest towns, highlighting the need for increased vigilance. The planned and ongoing study in and around Arba Minch will contribute to understanding the bionomics and role of An. stephensi in malaria parasite transmission, helping develop a strategy to address the impending risk of urban malaria in Ethiopia.

In this study, we compared the efficacy of geometric morphometric techniques, including outlines and landmark-based approaches, to support the differentiation of Trichodina bellottii from three co-occurring killifish species. Both methods were able to differentiate trichodinids from different host species. However, discriminat analyses and MANOVA results based on landmarks had greater accuracy possibly because these analyses only provide information on certain points defined by the researcher, while the analyses based on outlines take into account points with less taxonomic information.

Aggregation is a fundamental feature of parasite distribution in the host population, but the biological implications of the aggregation indices used to describe the relationships between the populations of parasites and hosts are not evident. It is speculated that the form of distribution in each case is predicated on the host's varying resistance to the infection, which is hard to control, making it difficult to adequately interpret the index values. This paper examines several cases from trout farms in Russian Karelia to explore the monogenean Gyrodactylus spp. infection in rainbow trout of varying ages. The genetic homogeneity of cage-reared fish and the direct life cycle of the helminths make the relationship between the species more lucid than in natural host-parasite systems. The results give no ground to speak of any specific patterns: as well as in the natural systems, the infection rates in trout vary widely, i.e., the helminth distribution has not become more uniform; the observed distributions in all cases are adequately approximated by the negative binomial model; the positive abundance-occupancy relationships (AORs) and abundance-variance relationships (AVRs) common for parasitic systems apply to the basic infection parameters. The form of the negative binomial distribution is shaped by two parameters-k and θ, the former being a metric of the infection variability, which depends on the host's individual resistance, and the latter representing the parasites' reproduction and establishment success rates. A rise in the parameter k indicates increased aggregation and a higher parameter θ points to a more uniform frequency distribution. These parameters can be used as a representative tool for monitoring the parasite communities in salmonid fishes, including in aquaculture.

The factors involving in the natural history and determinants of different features of human cystic echinococcosis (CE) are not adequately understood. Several host-related factors including the genetic structure of the host and human leukocyte antigens (HLAs) are believed to be involved in the natural history of CE in humans. The present study was conducted to investigate the association between HLA class II genes and active and inactive stages of hepatic cystic echinococcosis. Echinococcus granulosus cyst samples and patient information were collected from the biobank of the Iranian Hydatid Disease Registry from 2019 to 2022. HLA-DRB and HLA-DQB were characterized by PCR method. CE patients were categorized into three active (CE1 and CE2), inactive (CE4 and CE5), and transitional (CE3) stages according to the WHO ultrasound classification of CE. In total, 77 participants including 38 patients (36.8% men and 63.2% women) with different stages of CE as well as 39 healthy individuals (38.5% men and 61.5% women) were included in the study. Findings of the study showed that the frequency of HLA-DRB1*03 was significantly lower in the patients compared to the healthy individuals. The frequencies of HLA-DQB and HLA-DRB alleles were not differed significantly between active, inactive, and transitional stages of E. granulosus cysts. Findings of this study indicate the potential role of this allele in the susceptibility of human to cystic echinococcosis. Further large-scale studies in different endemic countries are required to document the significance of HLA-DQB and HLA-DRB as a host-related factor in the natural history of CE in human.