Parasite最新文献

Species of Seuratascaris Sprent, 1985 are a rarely reported group of ascaridoid nematodes, parasitising various frogs and toads. In the present study, a new subspecies of Seuratascaris, S. physalis bazhaiensis n. subsp. was described using integrated taxonomic methods, based on specimens collected from Odorrana graminea (Anura: Ranidae) in Guangxi Zhuang Autonomous Region, China. Results of the Assemble Species by Automatic Partitioning (ASAP) and Bayesian inference based on the mitochondrial cox1, cox2 and rrnS data all supported S. physalis bazhaiensis representing a distinct taxon from the nominate subspecies S. physalis physalis. Supplementary morphometric and genetic data of S. phy. physalis are presented based on newly collected material from Odorrana tiannanensis (Anura: Ranidae) and Rhacophorus sp. (Anura: Rhacophoridae) in Yunnan Province, China. A key to species of Seuratascaris is provided. The complete mitochondrial genome of S. physalis bazhaiensis was sequenced and annotated, and represents the first mitogenomic data for the genus Seuratascaris. This mitogenome has only 13,628 bp (including 12 protein-coding genes, 22 tRNA genes, 2 ribosomal RNAs, and only 1 non-coding region), and is the smallest of the reported ascaridoid mitogenomes so far.

Parasitic infection by endoparasites is heterogeneous within a population. Such heterogeneity in parasitic status among individuals depends in particular on differences in their susceptibility to infection and in the habitats and resources used by the individuals. While several studies have aimed to identify individual factors and, mostly at large spatial scales, environmental factors that influence endoparasitism in wild populations, we aim in this study to investigate the influence of habitat quality (vegetation type, resource availability) on parasite burden within a population of roe deer living in a heterogeneous forest. We collected 1,469 fecal samples to measure the parasite burden on 952 roe deer captured between 1996 and 2020 in Chizé (France), a study site stratified into two contrasting sectors in terms of vegetation structure and resource quality. We quantified the effect of the sector on parasitism after considering the possible influences of age, sex, body mass and Julian date. The prevalence of parasitism was higher in individuals living in the poorer sector, but the intensity of the parasite burden was not influenced by the sector. These results suggest that within a host population, parasite infection risk would not be the same everywhere, probably due to differences in resource availability, vegetation species and density of host, showing the need to study parasitism at fine scales.

According to the classical Enemy Release Hypothesis, one reason for the success of invasive species is that they have escaped their predators and parasites during migration to newly invaded territories. In this context, the discovery of any parasite of an invasive species is of particular interest. Here, we report the results of genomic investigations performed on two invasive species of land flatworms (Geoplanidae) collected in Northern Ireland, Kontikia andersoni Jones, 1981, and Australoplana sanguinea (Moseley, 1877). We describe the mitogenomes and paralogous RNA genes of both species. Prey DNA was detected in both flatworm species, providing molecular evidence that their diet includes earthworms. Unexpectedly, we detected sequences assigned to the microsporidian genus Mitosporidium Haag et al., 2015, which, prior to this study, included a single species. Each land flatworm species harboured its own species of Mitosporidium. For nomenclatural reasons, we could not assign binomial names to these species; instead, we designate them as Mitosporidium sp. JL467 (in K. andersoni) and Mitosporidium sp. JL472 (in A. sanguinea). For each new Mitosporidium species, we describe the gene content of the mitogenome and the complete cluster of nuclear ribosomal RNA genes. In the absence of direct evidence of host-parasite relationships, we discuss the possible hosts of these Microsporidia, which could be the flatworms themselves or their prey; the most likely hypothesis is that they are parasites of land flatworms. Other Mitosporidium species should be sought for in native land flatworms from the Australasian region, where the two invasive flatworm species originated. Investigations on the possible pathogenic role of these parasites are needed.

The invasive hornet Vespa velutina Lepeletier, which first invaded South Korea in 2003, has spread throughout the country, significantly affecting apiaries, ecosystems, and human health. Xenos spp. (Xenidae, Strepsiptera) are primarily parasitic to social wasps, with V. analis being the only known host in Korea. Until recently, no parasites or parasitoids on V. velutina had been discovered. In 2020, strepsipteran parasites were discovered on 11 hornet workers in Andong City, South Korea. These parasites, comprising four larvae and seven pupae, were all male, except for one individual of an undetermined sex. Molecular analysis and morphological examination identified the parasites as Xenos moutoni (du Buysson, 1903) and X. oxyodontes Nakase & Kato, 2013. This marks the first recorded instance of strepsipteran parasites on V. velutina in regions invaded by this hornet. Although the exact infection rate of these parasites could not be determined, it appears that native strepsipteran parasites have adapted to a non-native Vespa species. Stylopization, the condition caused by these parasites, is known to negatively affect hornet colonies: infected workers do not contribute to nest activities, hindering nest development, and infected reproductive individuals (males and new queens) do not mate, which impedes the establishment of new colonies. However, due to the hornet's high reproductive rate and compensatory mechanisms, the overall control effect of the parasites is likely to be minor.

The Milu deer, or Père David's deer (Elaphurus davidianus), a rare endemic species in China, represents a case of successful reintroduction of a species previously considered extinct in the wild. Trichomonads, protozoan symbionts capable of infecting vertebrates, are transmitted via the fecal-oral route; they are a subgroup of Parabasalia and include some pathogenic species that pose zoonotic risks. Until now, data on the diversity and prevalence of trichomonads in Chinese Milu deer have not been reported. To better understand the colonization status of trichomonads, fecal samples from 112 Milu deer across five nature reserves in China were collected. The ITS-1/5.8S/ITS-2 sequences were amplified using PCR to investigate the colonization rate of trichomonads and to assess evolutionary relationships and genetic characteristics through phylogenetic analysis. An occurrence of 38.39% was recorded in Milu deer, with sample collection sites (OR = 55.159, 95% CI = 3.166-961.113, p = 0.006), high relative humidity and average annual rainfall (OR = 11.675, 95% CI = 1.747-77.781, p = 0.011) identified as significant risk factors for trichomonads colonization. Undescribed trichomonads from four genera were identified, including Simplicimonas spp., Hypotrichomonas spp., Hexamastix spp., and Tetratrichomonas spp. To our knowledge, this is the first study to report on trichomonads in Milu deer in China. This study aims to enhance understanding of trichomonad colonization and associated risk factors, providing scientific guidance for the ex-situ conservation of Milu deer.

Cryptosporidiosis, caused by a Cryptosporidium infection, is a serious gastrointestinal disease commonly leading to diarrhea in humans. This disease poses a particular threat to infants, young children, and those with weakened immune systems. The treatment of cryptosporidiosis is challenging due to the current lack of an effective treatment or vaccine. Ongoing research is focused on understanding the molecular pathogenesis of Cryptosporidium and developing pharmacological treatments. In this review, we examine the signaling pathways activated by Cryptosporidium infection within the host and their role in protecting host epithelial cells. Additionally, we also review the research progress of chemotherapeutic targets against cryptosporidia-specific enzymes and anti-Cryptosporidium drugs (including Chinese and Western medicinal drugs), aiming at the development of more effective treatments for cryptosporidiosis.

Amblyomma maculatum, the Gulf Coast tick, is a species of significant veterinary and public health importance, especially because it is a vector of important diseases, such as American canine hepatozoonosis and tidewater spotted fever. Amblyomma maculatum infests a wide range of vertebrates including livestock, dogs, cats, and humans. Two experimental studies were conducted to evaluate the efficacy of afoxolaner formulated in an oral tablet (NexGard^®) against induced infestations of A. maculatum in dogs. These Good Clinical Practice (GCP) studies used a randomized, negative controlled and masked design. In each study, 10 dogs were allocated to an untreated group and 10 dogs to a treated group, dosed once on Day 0 with a combination of tablets targeting the minimum therapeutic dose (2.5 mg/kg afoxolaner). Dogs were infested with 50 unfed adult A. maculatum on Days -2, 7, 14, 21, 28, and 35 (Study #1), or on Days -1, 14, and 28 (Study #2). Seventy-two (72) hours after treatment and subsequent infestations, ticks were removed and the numbers of live ticks in each group were used for efficacy calculations. At each time-point, all untreated dogs were adequately infested (i.e., with more than 12 live ticks), demonstrating a vigorous tick population and an adequate study model. The curative efficacy against established infestations, 72 hours after treatment, was 100% in Study #1 and 99.5% in Study #2. The preventive efficacy, 72 hours after the post-treatment infestations, ranged from 94.6% to 98.9% for five weeks in Study #1, and was ≥98.8% for four weeks in Study #2.

The introduction of non-native pet-traded species poses potential threats to global biodiversity, particularly in freshwater ecosystems. This study investigated the seasonal dynamics of microsporidian infections in an established feral population of cherry shrimp (Neocaridina davidi) and the coexisting populations of crustaceans, comprising both native and non-native species, inhabiting the thermal waters of the Fontcaude Park and the nearby Mosson River in southern France. Our aim was to assess the potential occurrence of spillover and/or spillback events between N. davidi and co-occurring crustaceans, as well as the influence of seasonal dynamics on these interactions. The prevalence and diversity of microsporidian parasites exhibited strong seasonal variations. Although parasites associated with the pet trade were not detected, we highlight the acquisition of native parasites by feral N. davidi, which seems to be a suitable alternative host for native host-generalist microsporidians. Our findings indicate that all prerogatives for spillback events to occur are met. Feral N. davidi may establish and survive year-round in European rivers with natural thermal regimes. Thus, human-mediated introductions can potentially alter parasite transmission dynamics in these ecosystems.

Babesia ovis is a tick-transmitted intraerythrocytic apicomplexan parasite that causes ovine babesiosis, a disease with high economic impact in endemic regions. Although Rhipicephalus bursa is a known biological vector of B. ovis, the dynamics of vertical (transovarial) transmission are poorly understood. In the present study, the transovarial transmission of B. ovis was investigated experimentally in four continuous generations of R. bursa under laboratory controlled conditions. A total of 11 sheep were used during the study. An initial stabilate co-infected with B. ovis and Theileria ovis was inoculated into a splenectomized sheep, followed by an infestation with Babesia-free adult R. bursa. Study of dead tick bodies and larval pools by molecular methodology confirmed the elimination of T. ovis and the vertical transmission B. ovis. Rhipicephalus bursa ticks derived vertically from F₁ to F₄ generations kept high levels of infection (98% in F₃ adults), and consistently led to severe clinical babesiosis in both immunosuppressed and immunocompetent sheep. Although all feeding stages became infected while feeding on their hosts, only adult ticks were able to transmit the parasite to vertebrate hosts. Our findings demonstrate that B. ovis can be transmitted vertically through several tick generations, while preserving its ability to cause severe disease, even without selective pressure. The virulent, mono-infected B. ovis strain developed in this study will provide an infectious challenge model for future vaccine and pathogenesis studies under field-relevant conditions.

The 11th International Symposium on Phlebotomine Sand flies (ISOPS XI) took place in Portorož, Slovenia, in September 2024 and brought together experts from around the world to discuss recent advances in the biology, ecology and control of phlebotomine sand flies and the pathogens they transmit. This report summarises the key findings of the symposium and is organised thematically by session. Key topics included the development of refined experimental models of Leishmania transmission, new insights into the interactions between vector, parasite and microbiota, and the detection of Leishmania donovani in new geographic regions. Advances in molecular diagnostics and surveillance technologies were emphasised, as were emerging concerns about insecticide resistance. The potential of paratransgenesis and symbiont-based vector control approaches was also emphasised. In a separate session, the CLIMOS project was presented, which integrates climate monitoring, ecological modelling and public health tools to develop an early warning system (EWS) for sand fly-borne diseases. Overall, the contributions to the symposium reflect the dynamic development of sand fly research in response to global environmental change and emphasise the importance of international collaboration in combating emerging vector-borne diseases.