Parasites, hosts and diseases最新文献

The Belén District in Loreto Region, Peru, is known for its extensive riverfront areas, where many houses are built on stilts and float during the rainy season. We conducted fecal examinations on 997 schoolchildren (ages 4-14 years; 488 boys, 497 girls) across 4 schools in Belén using the Kato-Katz thick smear and formalin-ethyl acetate sedimentation techniques. The results revealed high rates of soilborne helminths and waterborne protozoan infections, with an overall parasite-positive rate of 79.7%. The primary helminth species were Ascaris lumbricoides (39.2%), Trichuris trichiura (33.2%), Hymenolepis nana (3.4%), hookworms (2.1%), and Enterobius vermicularis (1.5%). The main pathogenic protozoans were Giardia lamblia (20.9%) and Entamoeba histolytica/E. dispar (14.2%), along with Cryptosporidium-like coccidian (4.6%). Non-pathogenic protozoans included Entamoeba coli (31.5%), Endolimax nana (15.1%), and Blastocystis hominis (3.7%). The intensity of soilborne helminth infections was very high for A. lumbricoides (average eggs per gram of feces per child: 18,589), followed by T. trichiura (1,501) and hookworms (160). The prevalence of anemia, often associated with malnutrition, was moderate at 33.1% (298 anemic children among 901 examined). Mass deworming was initiated with albendazole 400 mg, 3 times a year, in conjunction with health education and environmental sanitation. Metronidazole was administered once at a dose of 200 mg 3 times daily for 10 days. A notable finding in this study was that soilborne and waterborne parasites are both highly prevalent among schoolchildren in the floating villages of the Belén District, Loreto Region. Sustained mass deworming is urgently needed and the WASH program is crucial.

Until now, 3 Metagonimus spp. (M. yokogawai, M. takahashii, and M. miyatai) causing human metagonimiasis have been reported in Korea. In this study, we investigated the possible presence of Metagonimus spp. other than these 3 species using human fecal samples from an endemic area in Korea. DNA was extracted from Metagonimus egg-positive fecal samples collected from residents of Gurye-gun, Jeollanam-do. A total of 21 representative mitochondrial cytochrome c oxidase subunit I sequences were obtained by PCR and cloning, and sequencing. Phylogenetic analysis revealed 1 cluster corresponding to M. yokogawai (n=10) and 2 additional distinct clusters corresponding to M. kogai (n=8) and M. saitoi (n=3), which were proposed as new species in Japan in 2022. Pairwise cytochrome c oxidase subunit I distances were low for M. yokogawai and M. kogai (mean Kimura 2-parameter: 0.005-0.006), whereas M. saitoi showed higher Korea-Japan values (~0.029), a pattern consistent with geographic structuring. In conclusion, we provide the first molecular evidence for the occurrence of M. kogai and M. saitoi in human fecal samples in Korea. Further confirmation using adult morphology, additional nuclear markers, and ecological surveys are needed to clarify metagonimiasis transmission in the Seomjin-gang (river) basin.

Perkinsus marinus is a significant pathogen in oyster aquaculture with expanding host and geographic ranges. This study evaluated the prevalence and infection intensity of P. marinus in major oyster farming regions across the USA, Mexico, Brazil, and Korea using a quantitative PCR (P. marinus-specific TaqMan quantitative PCR assay, Pm-qPCR) assay. Eastern oysters (Crassostrea virginica) were sampled from 7 USA sites, while Pacific oysters (Magallana gigas) were collected from Mexico, Brazil, and Korea. Compared to conventional PCR, the Pm-qPCR assay demonstrated significantly higher sensitivity, detecting P. marinus in >80.0% of samples at most sites and up to 100.0% in Port Norris, USA. Lower prevalence was found in Wellfleet, USA (58.0%) and Korean sites (63.0%-70.0%). The lowest infection intensities (<1,000 copies) were recorded at a high-energy open-water site in Buan, Korea. The assay's specificity was confirmed using negative control oysters from Canada. These findings provide critical baseline data on P. marinus distribution and emphasize the superior diagnostic value of Pm-qPCR for early detection. As P. marinus spreads globally, sensitive and standardized tools like this assay are essential for disease surveillance and aquaculture biosecurity.

Helminth-mediated immunomodulation has been extensively studied in animal models, demonstrating its potential as both a prophylactic and therapeutic option for inflammatory lung diseases. However, its role in attenuating respiratory virus-induced inflammation remains largely unexplored. In this study, we examined whether pre-existing infection with the helminth Trichinella spiralis confers protection against pulmonary pathology induced by respiratory syncytial virus (RSV) infection in mice. Mice with prior T. spiralis infection exhibited reduced pulmonary inflammation and lower viral titers in the lungs compared with RSV-infected controls. Transcriptomic profiling of lung tissue using RNA sequencing identified 407 differentially expressed genes. Among these, enrichment was observed in categories associated with the Gene Ontology (GO) terms "inflammatory response" (GO:0006954) and "defense response to virus" (GO:0051607). Selected genes from these categories were further validated by quantitative real-time PCR. Validation confirmed that co-exposure to T. spiralis and RSV resulted in attenuated expression of inflammation-related genes. Collectively, these findings demonstrate that pre-existing T. spiralis infection can alleviate virus-induced pulmonary pathology and inflammation, highlighting its potential as a novel therapeutic approach for respiratory inflammatory diseases.

The human gut is host to a diversity of microorganisms, including a parasite called Blastocystis. While there are increasing reports characterizing Blastocystis subtypes (STs) among healthy individuals, only a few studies have investigated the Blastocystis STs in renal or dialysis patients. This study investigates the Blastocystis prevalence and STs in hemodialysis patients. Fifty healthy controls and 100 chronic kidney disease patients undergoing dialysis participated in the study. Blastocystis infection was identified by using microscopic and molecular diagnosis using 18S rRNA-PCR. Then all positive samples were sent for sequencing to identify which ST they belong to. Phylogenetic and pairwise distance analyses were performed to confirm the validity of the STs. Thirty-four hemodialysis patients were infected with Blastocystis while 17 patients in the control were infected with the parasite. All positive samples were then confirmed using PCR. Genetic sequencing analysis subsequently revealed that 66% of Blastocystis infection belonged to ST1 and ST3 (33% each), followed by ST10 (20%), and ST6 (14%). The nucleotide sequence analysis of the 385 bp 18S rRNA gene revealed a >97% identity with previously identified Blastocystis isolates. The genetic analysis showed that the 8 identified isolates correspond to previously observed alleles. Six ST1 isolates produced a high frequency of Blastocystis isolates matching allele 4, with very low genetic divergence. ST3 isolates showed relatively increased genetic diversity and matching allele 34, which is the most common allele worldwide.

Perkinsus marinus is a major protozoan pathogen of oysters, responsible for severe mortality events and substantial economic losses in the global aquaculture industry. Rapid, sensitive, and reliable detection of this parasite is therefore essential for effective monitoring and timely control of dermo disease outbreaks. In this study, we developed and optimized a novel loop-mediated isothermal amplification (LAMP) assay, designated Pm-LAMP, for the specific detection of P. marinus in oyster tissues. The optimized Pm-LAMP assay, employing 5 primers and performed at 67°C, demonstrated high analytical sensitivity, consistently detecting DNA concentrations as low as 40 fg/µl and enabling accurate quantification down to 0.4 pg/µl. The assay exhibited linear amplification across a wide template range from 4 ng/µl to 0.4 pg/µl, with a strong inverse correlation between template concentration and threshold time. Specificity testing confirmed exclusive amplification of P. marinus, with no cross-reactivity observed for P. olseni, P. honshuensis, or P. chesapeaki. This study represents the first LAMP assay specifically designed for the detection of P. marinus. The Pm-LAMP assay was validated using Pacific oyster tissues and cultured P. marinus isolates originating from the USA and Korea and was benchmarked against quantitative real-time PCR (qPCR). Although qPCR exhibited higher sensitivity for detecting trace DNA levels, the Pm-LAMP assay produced results within 20 min while maintaining reliable detection at low DNA concentrations. Diagnostic performance evaluation showed 100% sensitivity and 90.91% specificity, with substantial agreement with qPCR (Cohen's κ=0.811). Overall, the Pm-LAMP assay provides a rapid, robust, and field-deployable diagnostic tool for P. marinus, supporting improved disease surveillance and sustainable oyster aquaculture management.

Plasmodium vivax merozoite surface protein-1 (PvMSP-1) is one of the major polymorphic markers for molecular epidemiological purposes. In particular, the interspecies conserved block 5-6 (ICB 5-6) of PvMSP-1 is a region exhibiting extensive genetic polymorphism. In this study, we analyzed polymorphic characters of the pvmsp-1 ICB 5-6 region from P. vivax isolates collected in 4 provinces of Vietnam (Dak Lak, Dak Nong, Gia Lai, and Khanh Hoa) between 2018 and 2022. A comparative analysis of pvmsp-1 ICB 5-6 sequences was also conducted between Vietnam and other endemic regions. A total of 139 pvmsp-1 ICB 5-6 sequences were obtained from 117 Vietnamese P. vivax isolates. Vietnam pvmsp-1 ICB 5-6 were clustered into 34 distinct haplotypes at the amino acid level, with the recombinant types being predominant. The pvmsp-1 ICB 5-6 from the Central Highlands, Dak Lak, Dak Nong, and Gia Lai, exhibited high genetic polymorphism, while the sequences from the South-Central region, Khanh Hoa, were less polymorphic. Highly diverse patterns of poly-glutamine (poly-Q) variants were identified in Vietnam pvmsp-1 ICB 5-6. Comparable features of genetic polymorphism were also identified in the global pvmsp-1 ICB 5-6 populations. Phylogenetic analysis of global pvmsp-1 ICB 5-6 revealed no significant country- or region-specific clustering. This study suggests that Vietnam pvmsp-1 ICB 5-6 exhibited a substantial genetic diversity with regional variations, implying the genetic heterogeneity of the Vietnamese P. vivax population. These findings emphasize the importance of continuous molecular surveillance to understand the genetic nature of the parasite in the country.

Giardia lamblia is a protozoan parasite responsible for Giardiasis, one of the most prevalent intestinal infections worldwide. Despite its medical relevance, the molecular organization of its transcriptional apparatus remains poorly characterized. Here, I present an integrative analysis of the structural and functional features of the Giardia nucleolus and its transcription machinery. Treatment with actinomycin D induces nucleolar disorganization, confirming active rRNA transcription and nucleolar stress. Additionally, I highlight the highly divergent TATA-binding protein as a potential therapeutic target, given its essential role in transcription and its low mutation rate. Collectively, these findings provide new insights into the minimalist eukaryotic architecture of G. lamblia and identify unique molecular elements that may serve as selective antiparasitic targets.

Vertical transfer of maternal antibodies can provide passive protection to offspring against specific pathogens. In this study, we detected antibodies in the sera of uninfected offspring born to chronically Trichinella spiralis-infected female mice. Immunoblotting consistently revealed a distinct band at ~38 kDa in both T. spiralis excretory-secretory products and total somatic extracts. This band was identified by MALDI-TOF/TOF mass spectrometry as a cystatin-like protein of T. spiralis (Ts-CLP). Structural modeling and domain analysis indicated a typical cystatin-like fold comprising a central α-helix and an antiparallel β-sheet core. To confirm antigen identity, recombinant Ts-CLP protein was expressed and used to generate a polyclonal anti-recombinant Ts-CLP protein antibody. This antibody specifically recognized a ~38 kDa band in T. spiralis excretory-secretory products and total somatic extracts, consistent with that detected by offspring sera. Collectively, these findings demonstrate that maternal antibodies specific to Ts-CLP are vertically transferred and detectable in uninfected offspring. Although the functional significance remains to be determined, this observation provides a basis for future studies on passive immunity and host-parasite interactions.

Trichomonas vaginalis infection causes vaginitis and cervicitis in women, and asymptomatic urethritis and prostatitis in men. Mast cells play a key role in the inflammatory response against T. vaginalis infection. In this study, we examined the signaling pathways involved in mast cell activation induced by T. vaginalis-derived secretory products (TvSP), focusing on IKK2, calcium, MAP kinase (MAPK), and PI3 kinase (PI3K). TvSP stimulation induced phosphorylation and degradation of IκB, indicating NF-κB activation, and triggered phosphorylation of ERK1/2, p38 MAPK, and AKT. TvSP also increased the surface expression of CD63, a marker of exocytosis, which was reduced by IKK inhibition, calcium chelation, or blockade of PI3K and PKC. Furthermore, inhibition of PI3K or MAPKs decreased TvSP-induced interleukin-8 production. These results suggest that IKK2 and calcium are critical for TvSP-induced degranulation, while PI3K and MAPK pathways contribute to interleukin-8 production in mast cells.