International journal for parasitology最新文献

The complex life cycle of Plasmodium parasites, involving both liver and blood stages of infection in the mammalian host, presents significant challenges for malaria research. Although advances have been made in malaria vaccination and treatment strategies, important gaps in our understanding of the asymptomatic liver stage of Plasmodium infection remain. While reporter gene-expressing parasites are commonly used for drug screening and parasite biology studies during this phase of the Plasmodium life cycle, tools for assessing and quantifying hepatic infection in the absence of parasite-encoded reporter genes are limited. Here, we present a novel flow cytometry-based method that enables the quantitative assessment of infection of hepatic cells by non-fluorescent Plasmodium parasites. This method uses two parasite proteins, heat shock protein 70 (HSP70), found in the parasite cytoplasm, and upregulated in infectious sporozoites 4 (UIS4), located on the parasitophorous vacuole membrane, as markers for parasite detection and quantification. We demonstrate that the use of these markers facilitates the rapid and cost-effective quantification of hepatic infection and intracellular development of Plasmodium parasites devoid of fluorescent reporter genes. This method addresses critical regulatory and technical challenges to the evaluation of reporter-free whole-sporozoite vaccine candidates and could serve as a versatile tool for broader malaria research.

Trypanosomatids are flagellated protozoa that infect a wide range of hosts. While Trypanosoma and Leishmania are extensively studied due to their medical importance, information regarding species infecting wildlife remains scarce. This study aimed to characterize trypanosomatids from Colombian amphibians, birds, and mammals using an integrative taxonomic approach. We sampled 46 birds, 18 reptiles and amphibians, and 124 mammals within the tropical dry forest of Tolima, Colombia. Detection was performed employing novel Hsp70 (671 bp) and 18S rRNA (1400-1900 bp) primers. Positive PCR products were sequenced using Oxford Nanopore Technologies for phylogenetic inference and species delimitation. Morphometric traits were measured from blood smears, and phenotypic variation was assessed via PCA and PERMANOVA. The combination of molecular markers, species delimitation, and morphometrics led to the discovery of three new species: Trypanosoma vallejoi n. sp. and Trypanosoma carranzai n. sp. in wild birds, and Trypanosoma guhli n. sp. in amphibians. This integrative framework provides a robust and cost-effective tool for trypanosomatid diagnosis in wildlife. These findings reveal a hidden diversity of trypanosomatids in Neotropical ecosystems and demonstrate the value of molecular tools in bridging wildlife surveillance with evolutionary and taxonomic research.

Giardiasis is a cosmopolitan parasitic infection caused by a protozoan pathogen Giardia intestinalis. A high number of failures complicates the metronidazole (MTZ) treatment. However, long-term studies characterising the parasites associated with MTZ treatment failures are lacking. This study was designed to map Giardia genotypes, clinical manifestations and geographical origin of giardiasis in a patient cohort from the Czech Republic. A multilocus genotyping was applied to 93 Giardia DNA isolates collected over five years in a tertiary care hospital diagnostic facility, and corresponding patient data, including the treatment outcomes, were evaluated. We found that treatment-refractory giardiasis (32.9% of infections) was always symptomatic, associated with South Asian origin and caused mainly by sub-assemblage BIII parasites. This study confirms the limited efficacy of MTZ treatment, especially in travellers returning from South Asia.

Trichinella chanchalensis (T13) remains poorly characterized, limiting understanding of its biology, freeze-tolerance, and zoonotic potential. One major challenge is that infective first-stage larvae can only be obtained from naturally exposed wildlife in northern North America, which often harbour co-infections with other Trichinella taxa. Therefore, we used next-generation sequencing (NGS) to identify naturally infected wolverines with high proportions of T13 larvae. We recovered larvae from muscle tissue previously frozen at -20 °C for up to 15 months and orally inoculated a total of 55 CD-1 and BALB/c mice, including immunocompetent and immunosuppressed groups, with doses of 21-581 larvae. Mouse carcasses were digested, and recovered larvae were genotyped using NGS. Establishment and recovery of T. chanchalensis larvae were consistently low, with only two larvae recovered from one BALB/c mouse in a pure infection and 2-913 larvae from immunosuppressed mice as mixed infections, despite good recovery of larvae of T. nativa and Trichinella T6. On repassaging in mice, only two T. chanchalensis larvae were recovered after the second passage. These results suggest poor adaptation of T. chanchalensis to laboratory mice, despite immunosuppression, and/or lower freeze-tolerance of T. chanchalensis compared to T. nativa and Trichinella T6. Differences in cold adaptation among northern Trichinella taxa likely reflect ecological and evolutionary pressures, with T. nativa considered the most freeze-tolerant, while T6 and T. chanchalensis exhibit comparatively lower tolerance. Understanding the biology and freeze-tolerance of T. chanchalensis is important for food safety and for developing One Health-informed surveillance to protect northern communities reliant on game meat.

Aquaculture intensification has transformed fish communities in Central European ponds, with common carp (Cyprinus carpio) now dominating harvests at the expense of diverse assemblages of cyprinids and percids. These changes are expected to alter parasite transmission to piscivorous birds, which serve as definitive hosts for helminths. We investigated helminth communities in two major avian predators, the great cormorant (Phalacrocorax carbo, n = 126) and the grey heron (Ardea cinerea, n = 577), from Czech fishponds at two time points: the late 1990s and 2022-2025. In cormorants, dietary analysis revealed a shift from a mixed prey of white fish and carp in 1997 to carp alone in recent years, including individuals exceeding 650 g. This dietary simplification coincided with significant declines in the prevalence and intensity of several dominant digeneans (e.g., Hysteromorpha triloba and Petasiger phalacrocoracis) and the nematode Contracaecum rudolphii, with coinfections now involving fewer helminth species and reduced overall burdens. Grey herons showed a different pattern. Prevalence of major taxa, particularly Apharyngostrigea cornu, Uroproctepisthmium bursicola, Echinochasmus beleocephalus, and Posthodiplostomum cuticola, remained relatively stable across decades. However, mean intensities declined, and individuals with high infection intensities were no longer observed. These contrasting outcomes reflect differences in foraging ecology, with cormorants tightly linked to pond fish stocks, whereas herons exploit broader habitat mosaics. Our findings demonstrate that aquaculture-driven simplification of fish assemblages cascades into parasite transmission networks, causing asymmetric erosion of helminth communities in definitive avian hosts. Helminths of fish-eating birds thus serve as sensitive bioindicators of ecological change in pondscapes dominated by carp production.