Parasite最新文献

Microcotylids have rarely been reported along the South African coast, even though the Microcotylidae is one of the dominant polyopisthocotylan families. The present study focused on elucidating the parasite diversity of the Cape white seabream, Diplodus capensis (Smith), from various localities along the South African coast. By combining molecular and morphological techniques, two previously undescribed species of the Microcotylidae were identified. Atriaster ibamba n. sp. primarily differs from its congeners by the number and size of the hooks surrounding the genital atrium. Polylabris dassie n. sp. has a single vagina and is unique to most others of this genus by having a smaller male copulatory organ, and by the shape of this organ. This is the first report of species of Atriaster from South Africa, as well as the first report of any polyopisthocotylan from D. capensis. The present study also contributes the first genetic sequences of marine microcotylids from South Africa.

Toxoplasma gondii is the protozoan parasite responsible for toxoplasmosis, a zoonosis that represents a health risk for mammals, including marine species. Felines are the only definitive hosts of this parasite, playing a critical role in the introduction and maintenance of the pathogen in a new environment. Recent data demonstrate the contamination by T. gondii of the terrestrial and seawater environment of the Galapagos archipelago, in the Pacific Ocean. Little is known about the exposure of Galapagos' threatened species to T. gondii, although introduced domestic cats in the archipelago are known to be seropositive for T. gondii. We documented for the first time exposure to T. gondii of Galapagos sea lions (Zalophus wollebaeki), an endemic and emblematic species of the archipelago. The modified agglutination test revealed the presence of antibodies against T. gondii in 61 of 77 plasma samples collected in 2016-2017 from 2- to 4-year-old wild sea lions live-handled in their breeding sites on the inhabited island of San Cristóbal. Antibodies were also detected in 4 of 19 serum samples (21%) from sea lions whose corpses were found in 2021 on the same island. In addition, T. gondii DNA was detected in a lung sample from one necropsied pup and a tissue cyst-like structure was found in another, suggesting infection. These results, together with the high prevalence of antibodies in 2 to 4-year-olds, indicate that Galapagos sea lions are frequently exposed to T. gondii and raise concerns that toxoplasmosis may pose a threat to this endemic species.

Innovative control tools are needed against Aedes mosquitoes. The boosted sterile insect technique (bSIT) consists of treating sterile males with a biocide prior to their release to contaminate larval habitats. We compared the efficacy of SIT and boosted SIT to prevent the emergence of adult Aedes albopictus in large cages. We tested two sterile-to-fertile male ratios: 5:1 (SIT5) and 1:1 (SIT1), with and without pyriproxyfen enhancement (bSIT or SIT). The eggs were collected in ovitraps and the immature stages were monitored until adult emergence or up to 15 days after hatching to estimate the relative risk (RR) of adult emergence compared to the control category. The concentration of pyriproxyfen in the ovitrap water did not change when sterile males were released with females or alone (χ² = 0.99, df = 1, p = 0.547). This concentration was higher when the sterile-to-fertile male ratio was increased from 1:1 to 5:1: χ² = 18.8, df = 1, p = 0.006. All four treatment categories were effective in suppressing mosquito populations. With a relative risk RR = 0.194 95% CI [0.128; 0.275], SIT5 was the most effective. Boosted SIT was not as effective as SIT. However, bSIT1 (RR = 0.418 [0.351; 0.492]) and bSIT5 (RR = 0.512 [0.431; 0.596]) were equally effective. Boosted males directly vectored pyriproxyfen to breeding sites. Boosted SIT was more effective than SIT alone with a low sterile-to-fertile male ratio. Under operational conditions, it could be initially deployed to suppress the target population and then switched to standard SIT.

China was once a major endemic zone for Schistosoma japonicum, but decades of control efforts have dramatically reduced transmission. Suzhou City, in Jiangsu Province, a former hyperendemic area, achieved transmission interruption in 1995. However, the intermediate host Oncomelania hupensis persists and new habitats in non-endemic villages pose resurgence risks if parasites are reintroduced. To evaluate genetic resilience and dispersal potential, we analyzed six O. hupensis populations (214 snails) from ecologically distinct habitats in Wuzhong district, Suzhou (2018 to 2021): Guangfu (GF20 and GF21: wetlands), Jinting (JT18, JT19, and JT20: isolated island), and Dongshan (DS19: lakeside hills). Using nine microsatellite loci, we identified 91 alleles and assessed genetic diversity, structure, and demography. All populations exhibited low observed heterozygosity (Ho < 0.5), with bottlenecks detected in GF21, GF20, and JT20. Paradoxically, infinite effective population sizes (Ne) at 95% CI upper limits suggested retained adaptive potential. Significant genetic differentiation (F_ST = 0.287, p < 0.01) reflected habitat-driven isolation: Jinting's island populations diverged markedly from Dongshan and Guangfu, while bidirectional gene flow (Nm > 1) between Guangfu's temporally sampled populations indicated sustained genetic connectivity over time. DIYABC modeling traced JT20's ancestry to admixture between Jinting (JT18) and Guangfu (GF20) sources, implicating flood-mediated dispersal. Despite local control efficacy, snails retain resilience via large Ne. These findings mandate habitat-tailored strategies: habitat modification and intensified molluscicide campaigns in Guangfu and targeted eradication of Jinting's isolated populations. Integrating genetic surveillance into snail monitoring programs will be critical to sustaining transmission interruption and achieving elimination in ecologically complex regions.

In addition to the ribosomal internal transcribed spacer (ITS) locus, four loci (MS1, MS3, MS4, and MS7) have been identified to develop multilocus sequence typing tools for high-resolution genotyping of Enterocytozoon bieneusi in previous studies. However, the use of only five loci was insufficient for population genetic analysis of E. bieneusi from diverse hosts. In this study, comparison of a clinical genome sequence (C44566) with the whole genome sequence of an E. bieneusi isolate (H348) in GenBank led to the selection of the hypothetical protein 1 (hp1) and tubulin 1 (tub1) loci. Further analysis of the two loci with 156 E. bieneusi-positive samples showed high sequence polymorphisms in ITS Groups 1-6 and 10. Altogether, 30 and 23 sequence types were identified at hp1 and tub1, respectively. Genotyping based on the two loci confirmed the lack of genetic differentiation between Group 1 and Group 2 genotypes, as previously reported. Moreover, the genotypes in Groups 4 and 5 are more divergent from other genotypes within Groups 1-10. However, isolates in Group 11 and 12 could not be amplified at the hp1 and tub1 loci, supporting the previous conclusion of genetic uniqueness of the two genotype groups. The identified genetic markers and generated data could be used to develop a multilocus sequence typing tool for high-resolution genotyping of E. bieneusi, which would also have implications for understanding the taxonomy of Enterocytozoon spp., the public health significance of E. bieneusi in animals, and sources of E. bieneusi infections in humans.

Cryptosporidium is a significant zoonotic parasite with broad distribution in both humans and rodents. In this study, 510 fecal samples were collected from nine species of wild rodents across Guangxi, Yunnan, and Hunan Provinces in China. Nested PCR analysis targeting the SSU rRNA gene revealed an overall Cryptosporidium infection rate of 1.8% (9/510) among rodents in these provinces. The highest positivity rate was observed in Guangxi Province at 4.9% (5/103), followed by Yunnan Province (2.3%, 2/88), and Hunan Province (0.6%, 2/319). Notably, Rattus losea exhibited the highest prevalence rate at 9.8% (4/41), while Rattus flavipectus and Niviventer lotipes showed rates of 5.1% (2/39) and 4.4% (1/23), respectively. Various genotypes/species were identified, including Cryptosporidium viatorum, Cryptosporidium muris, Cryptosporidium vole genotype VII, and Cryptosporidium ratti, rat genotypes II, and IV. The study also found that wild rodents inhabiting mountainous areas had a higher prevalence rate at 4.9% (5/103) compared to those residing in fields and lake beaches, where prevalence rates were 2.1% (2/95) and 0.6% (2/312), respectively. This study provides new insights into Cryptosporidium infection rates among wild rodents and identifies two zoonotic species, C. viatorum and C. muris. These findings underscore the potential risk posed by Chinese wild rodent populations in transmitting zoonotic Cryptosporidium, which could significantly impact public health. Therefore, effective control strategies are needed to prevent transmission between humans and rodents.

Dactylogyrids are flatworms of ecological and economic significance, parasitizing fish worldwide. In recent years, there has been a surge in the description of Neotropical dactylogyrids, particularly those infecting siluriform fishes. While these studies have contributed to the organization of some genera and refined species boundaries through integrative taxonomy, certain groups within the family, such as Demidospermus, remain taxonomically unstable. This study focuses on Demidospermus, aiming to reclassify species of uncertain status into appropriate genera and establish a morphological framework to support future evolutionary analyses and taxonomic revisions within the Demidospermus-like species group. Supported by morphological phylogenetic analysis, we propose the new genera Rhabdolachosus n. gen., Martorellius n. gen., Magnanchistrius n. gen., and Sicohencotyle n. gen., along with the resurrection of Omothecium Kritsky, Thatcher & Boeger, 1987, and Paramphocleithrium Suriano & Incorvaia, 1995. Additionally, two new species are described: Sicohencotyle antoniomaiai n. gen. n. sp. and Ameloblastella sakulocirra n. sp. Also, Demidospermus centromochi Mendoza-Franco & Scholz, 2009 is classified as sedis mutabilis, while D. annulus Marcotegui & Martorelli, 2011, D. brevicirrus Mendoza-Palmero et al., 2012, D. cornicinus Kritsky & Gutierrez, 1998, D. idolus Kritsky & Gutierrez, 1998, D. armostus Kritsky & Gutierrez, 1998, D. mortenthaleri Mendoza-Palmero et al., 2012, D. osteomystax Tavernari et al., 2010, D. tocantinensis Cohen et al., 2020, D. doncellae Morey et al., 2024, D. bifurcatus Justo, Martins & Cohen, 2024, D. juruaensis Justo, Martins & Cohen, 2024, and D. takemotoi Justo, Martins & Cohen, 2024 are considered incertae sedis. Lastly, Urocleidoides amazonensis Mizelle & Kritsky, 1969 remains classified as incertae sedis.

There are estimated to be over one billion human infections of Toxoplasma gondii worldwide. However, significant spatial heterogeneity exists across countries and regions. For this study, a total of 2,943 participants were enrolled between 2019 and 2023 in Zhejiang Province, southeastern China including 519 animal contact workers, 1,722 people from the general population, and 702 blood donors. Anti-T. gondii IgG and IgM in sera were assessed using an enzyme-linked immunosorbent assay. The overall seroprevalence of IgG and IgM was 4.08% and 0.41%, respectively. IgG positivity was highest in the (50, 60] years age group (5.47%, 29/530), while IgM was found in the (60, 70] years age group (1.21%, 3/247). The general population showed the lowest IgG seroprevalence (1.68%) compared to animal contact workers (10.40%) and blood donors (5.27%) (p < 0.001). Patterns of T. gondii IgG prevalence varied by participant type. Increasing seroprevalence with age was observed among animal contact workers, indicating a cumulative effect, while frequency was highest in the (50, 60] and (30, 40] age groups in the general population and blood donors, respectively. Animal contact workers with two types of animal exposure had higher IgG positivity rates (13.16%) than those with one type (8.50%). Occupational exposure to cattle was associated with the highest frequency of IgG (12.69%), followed by pigs (9.69%), and sheep (8.85%). This study provides critical insights into the epidemiological characteristics of T. gondii infections across distinct population groups in Eastern China.

Plasmodium cynomolgi is an emerging zoonotic malaria parasite in Southeast Asia, infecting both humans and macaques. In this study, we investigated mutations in the DHFR and DHPS genes of P. cynomolgi from humans and macaques, comparing them to known resistance mutations in P. falciparum and P. vivax. We also examined how these mutations affect antifolate drug binding, which may influence treatment efficacy and resistance. Nine asymptomatic human blood samples from Cambodia and 29 macaque samples from Thailand were analyzed. Human samples included eight P. cynomolgi monoinfections and one mixed infection with P. vivax, while all macaque samples were monoinfections. The PcyDHFR and PcyDHPS genes were amplified, sequenced, and subjected to haplotype analysis. Human samples from Battambang, Cambodia were 100% identical to the P. cynomolgi RO strain, showing no DHFR mutations and one DHPS mutation (V451I). In contrast, macaque samples from Saraburi, Thailand showed PcyDHFR mutations N44T and C49S, and two haplotypes based on I7 variation - haplotype 1 (72.41%) with wild-type I7 and haplotype 2 (27.59%) with the I7 mutation. PcyDHPS mutations were identical across macaque isolates. Protein structures of PcyDHFR and PcyDHPS were modeled using SWISS-MODEL, focusing on the N- and C-terminals. Mutations occurred near catalytic sites but did not significantly affect binding affinity, based on molecular docking with eight antifolate drugs. These findings suggest that current antifolate drugs remain potentially effective against P. cynomolgi, and highlight the importance of monitoring drug resistance in zoonotic malaria.

Haemosporidian parasites from the genera Haemoproteus, Plasmodium, and Leucocytozoon are significant avian pathogens. This study aimed to identify and characterize these parasites in cranes (family Gruidae), using combined morphological and molecular methods. The results confirmed the presence of Haemoproteus balearicae, redescribed here from Balearica regulorum and associated with cytb lineage hBAREGI210. This lineage, previously assigned to Haemoproteus antigonis, is reassigned to H. balearicae, suggesting possible cryptic speciation within the H. antigonis complex. The findings broaden the known host range and geographic distribution of H. balearicae, detected in captive-born cranes in France and captive cranes housed in conservation facilities in South Africa. Phylogenetic analyses revealed three distinct Haemoproteus clades in Gruidae, corresponding to at least three species, including H. balearicae and lineages representing H. antigonis. These crane-specific parasites may require taxonomic revision as a separate subgenus or genus, pending further studies on their life cycles and vectors. Additionally, several novel cytb lineages of Plasmodium and Leucocytozoon were detected, many unassigned to morphospecies. Notably, the pCATUS05 lineage, a member of the Plasmodium lutzi group previously reported only in the Americas, was detected for the first time in South African cranes, along with Leucocytozoon aff. californicus (lCIAE02), a widespread lineage lacking morphological description. Together, these findings reveal underestimated genetic diversity of haemosporidian parasites in cranes and highlight the importance of combining morphological and molecular data to clarify parasite taxonomy and host associations. This study advances our understanding of avian parasite ecology and systematics, with implications for crane conservation and disease management.