Parasites, hosts and diseases最新文献

Avian schistosomes, mainly belonging to the genus Trichobilharzia, are the etiological agents of cercarial dermatitis in humans. The aims of this study were to report a human case of cercarial dermatitis contracted in a paddy field in a natural regeneration area in Tokyo, Japan, and identify the etiological agents of this case using molecular phylogenetic analyses. A snail survey was conducted between 2021 and 2023 in a rice paddy field where a case of cercarial dermatitis occurred, and molecular phylogenetic analyses of the furcocercariae and parasitized lymnaeid snails were performed based on the partial sequence of the mtDNA cox1 gene. Furcocercariae were detected in 11 (2.7%) of the 413 lymnaeid snails examined, and all 120 pleurocerid snails tested negative for cercariae. The cercarial larvae possessed a pair of eye spots and a characteristic bifurcated tail. Phylogenetic analyses of the cox1 genes identified the furcocercariae as Trichobilharzia sp., and the lymnaeid snails were Radix plicatula. This study demonstrated that the life cycle of a Trichobilharzia sp., using R. plicatula as an intermediate host, is established in an urban natural restoration area in Tokyo, serving as a source of human cercarial dermatitis. This study emphasizes the need for an increased awareness of cercarial dermatitis as a potential public health concern.

Acanthamoeba is a genus of free-living amoebae commonly found in soil, water, and other habitats. This organism undergoes 2 distinct stages in its life cycle, the trophozoite and the cyst. Under adverse conditions, trophozoites transform into cysts, which are notably resistant to harsh physical and chemical conditions. Infected by Legionella pneumophila has been shown to decrease the number of cysts in its host Acanthamoeba species, although the mechanisms responsible for this effect remain poorly understood. In this study, A. castellanii was co-cultured with either L. pneumophila or Escherichia coli to assess the impact on encystation and to explore the genes involved in this process. Following a 72-h encystation induction period, it was observed that Acanthamoeba infected with Legionella exhibited a 45.8% reduction in cyst formation compared to the control group. In contrast, Acanthamoeba that phagocytosed E. coli showed a 21.7% decrease. To identify the genes involved in this phenomenon, real-time PCR analysis was conducted on 20 genes known to be upregulated during encystation. This analysis was performed to verify their expression patterns at 24, 48, and 72 h. Notably, ten genes, including cyst-specific protein 21, glycosyltransferase, RSNARE, and cellulose synthase, did not exhibit increased expression in Legionella-infected Acanthamoeba. However, these genes showed elevated expression levels in both the control group and the bacteria-phagocytosed Acanthamoeba. This suggests that several cellular processes, including cell wall formation, are inhibited in Acanthamoeba infected with Legionella, resulting in reduced encystation.

Feline heartworm (Dirofilaria immitis) infection is an uncommon but clinically significant disease in Korea. A retrospective review of electronic medical records from a secondary referral animal hospital in Ulsan, Korea, identified 2 antigen-positive (1.5%) cases among 130 stray cats tested between 2019 and 2023, while no infections were detected in 298 client-owned cats. As antigen testing may yield false-negative results in cats with male-only infections, the true prevalence is likely underestimated. This report describes the clinical and echocardiographic findings of 2 infected stray cats. Case 1 involved successful long-term management of heartworm-associated respiratory disease, with the cat remaining healthy for 4 years following diagnosis. Case 2 demonstrated persistent evidence of adult heartworms and sudden death after an asymptomatic period of 1 year. Echocardiography in Case 2 revealed multiple hyperechoic double lines within the pulmonary arteries, consistent with intraluminal adult worms. These cases illustrate the diagnostic challenges and variable clinical outcomes of feline heartworm infection, emphasizing the need for increased awareness in Korea.

The Oriental stork (Ciconia boyciana Swinhoe, 1873) is an endangered species, with active restoration efforts ongoing in Korea. Despite the ecological importance of host-specific parasites, such as chewing lice (Phthiraptera), information on the chewing lice fauna associated with C. boyciana in Korea remains unclear. Previous records of 2 chewing louse species from the host have been questioned due to potential misidentification. To clarify the chewing lice fauna of the host, we conducted a survey of captive C. boyciana at Yesan Oriental Stork Park, Korea, in October 2022. Morphological identification of collected louse specimens revealed 3 species: Neophilopterus incompletes (Denny, 1842), Ardeicola ciconiae (Linnaeus, 1758) and Colpocephalum zebra Burmeister, 1838. These species are typical ectoparasites of Ciconiiform birds and represent the first verified louse records of chewing lice from C. boyciana in Korea. Unlike with a previous report, Cuclotogaster heterographus (Nitzsch, 1866) and Anaticola anseris (Linnaeus, 1758) were not detected. Our findings provide an updated checklist of chewing louse species for C. boyciana in Korea, contributing to a more accurate understanding of host-parasite associations and supporting future conservation efforts for both the host and its associated parasite fauna.

Naegleria fowleri is a free-living amoeba that can cause primary amebic meningoencephalitis (PAM), a very serious infection of the central nervous system. Early diagnosis of PAM is challenging, and the condition is almost always fatal. In this study, we conducted 2-dimensional gel electrophoresis (2-DE) analysis using N. fowleri trophozoite lysates and conditioned media to identify preferentially secreted proteins. As a result of the 2-dimensional gel electrophoresis analysis, 1 protein was found to increase, 5 proteins were found to decrease, 3 proteins showed a qualitative increase, and 15 proteins showed a qualitative decrease in the conditioned media compared to the proteins in the trophozoite lysates. Using cDNA from N. fowleri, Acanthamoeba castellanii, and Balamuthia mandrillaris, all of which can cause encephalitis, real-time PCR was performed on 5 genes corresponding to the p23-like domain-containing protein, cystatin-like domain-containing protein, fowlerpain-2, hemerythrin family non-heme iron protein, and an uncharacterized protein. The results showed that all 5 genes were highly expressed in N. fowleri. In animal models infected with N. fowleri resulting in PAM, real-time PCR analysis of brain tissue revealed significant overexpression of the p23-like domain-containing protein and fowlerpain-2. These results suggest that the 2 secreted proteins could provide valuable insights for developing antibody-based or molecular diagnostic methods to detect N. fowleri in patients with PAM.

Hepatic alveolar echinococcosis (HAE), a life-threatening zoonosis, poses formidable surgical challenges when involving critical vasculature. Herein, we reported the periprocedural management dilemmas in radical resection for advanced HAE. A 58-year-old female visited the outpatient department presented with HAE. Imaging examination revealed extensive invasion of the hilum, bile duct, and several hepatic vessels, as well as left adrenal metastasis. The patient underwent right trisegmentectomy with left hepatic vein reconstruction, auto-transplantation, and adrenalectomy, with intraoperative Doppler demonstrating patent portal flow before abdominal closure. However, emergency thrombectomy and transcatheter thrombolysis were performed due to the abrupt occurrence of portal vein thrombosis 3 h after surgery. Despite intervention, the residual liver volume remained insufficient (approximately 28% of the standard liver volume), leading to progressive liver failure. The patient expired from multiorgan failure 9 days after operation. This case underscores not only the critical balance between radical resection and preservation of residual liver function in the surgical management of complex HAE, but also the imperative need to establish a comprehensive postoperative thromboprophylaxis.

Toxoplasma gondii is an intracellular protozoan parasite capable of causing chronic infection by forming persistent cysts in the brain. Despite its global burden, no approved vaccine exists. Virus-like particle vaccines expressing microneme protein 8 (MIC8) or apical membrane antigen 1 (AMA1) of T. gondii have previously shown efficacy. In this study, we generated recombinant vaccinia viruses (rVVs) expressing MIC8 and AMA1 and evaluated their efficacy against T. gondii ME49 infection. BALB/c mice were intramuscularly immunized with a combination of MIC8 and AMA1 rVVs and challenged orally with T. gondii ME49. Immunization with MIC8+AMA1 rVVs produced a significant increase in T. gondii-specific IgG. Splenocyte analysis revealed robust activation of CD4+ and CD8+ T cells, as well as expansion of memory B cells. The immunized group exhibited an 89.6% reduction in brain cyst count, with significantly improved survival compared to the control group. These findings demonstrate that combining the antigens MIC8 and AMA1 using a vaccinia virus platform can effectively promote both humoral and cellular immunity, supporting its potential as a vaccine strategy against T. gondii ME49.

Caryophyllaeus brachycollis mainly parasitizes the intestines of globally distributed freshwater fishes, and infection causes significant economic losses to the aquaculture industry. However, data on the molecular epidemiology, population genetics, and systematics of C. brachycollis are scarce. In this study, we sequenced the complete mitogenome of C. brachycollis isolated from Beijing, China. This circular mitogenome comprised 14,273 bp, which was 231 bp shorter than that of C. brachycollis isolated from Wuhan, China. The mitogenome contained 12 protein-coding genes, 22 transfer RNA genes, 2 ribosomal RNA genes, and 2 noncoding regions. Bayesian inference revealed that C. brachycollis belonged to the family Caryophyllaeidae. The taxonomic status of C. brachycollis is controversial when based solely on morphological features. A comparative analysis of the mitogenome sequence obtained in this study revealed novel molecular markers for the accurate ascertainment of the phylogenetic position of this parasite.

The leopard cat (Prionailurus bengalensis) is a wild felid species that serves as a reservoir of zoonotic parasites. In this study, we investigated intestinal parasite taxa by reanalyzing previously published shotgun metagenomic sequencing data from fecal samples of wild leopard cats using a custom 18S rRNA gene reference database constructed from the NCBI nucleotide database. Among 11 metagenomic samples, 5 parasite species were identified: Toxoplasma gondii, Clonorchis sinensis, Strongyloides planiceps, Cylicospirura petrowi, and Pharyngostomum cordatum. These findings demonstrate that shotgun metagenomic analysis of fecal samples can be a useful tool for monitoring zoonotic parasite infections in this species and for investigating parasite life cycles. However, this approach is limited by its dependence on existing reference databases and requires experimental validation of the findings.

We present a nearly complete mitochondrial genome (mitogenome) of Hymenolepis diminuta from a Danish isolate, which was reassembled and comprehensively annotated using whole-genome sequencing data retrieved from the Sequence Read Archive (accession No. ERS056110). Although 2 mitogenomes of H. diminuta have previously been submitted to GenBank (accession No. AP017664, Danish isolate; NC_002767, putative German laboratory strain), the former lacks noncoding regions, while the latter harbors relatively short repeat units. Our newly reconstructed mitogenome is 14,090 bp long, comprising 12 protein-coding genes, 22 transfer RNA genes, 2 ribosomal RNA genes, and a 643-bp noncoding region containing 7 tandem repeat units. The annotated sequence has been deposited in the Third Party Annotation database in GenBank (accession No. BK071817). Phylogenetic analysis based on mitogenomic sequences confirmed a close relationship between H. diminuta and Hymenolepis nana. This improved mitogenome sequence represents a valuable resource for comparative mitogenomic and phylogenetic investigations within the families Hymenolepididae, Taeniidae, and Diphyllobothriidae.