Parasitology Research最新文献

This review paper outlines the history of giardiasis caused by Giardia duodenalis. Discovered in 1681, G. duodenalis is probably the first protozoan parasite ever observed by a human. Despite the early discovery, the taxonomic status of the protozoan remained uncertain for a long time. The reason for this is that G. duodenalis is a species complex comprising several phylogenetically distinct genotypes termed assemblages. Initially, it was thought that G. duodenalis is a primitive eukaryote because it lacks many subcellular organelles. However, recent research has shown that the protozoan has diverged from higher eukaryotes and that the lack of subcellular organelles is due to secondary loss and reduction. Based on paleoparasitological findings, G. duodenalis has parasitised humans since antiquity and has probably been spread globally by human migratory activity. Interestingly, it was not until 1987 that the pathogenicity of G. duodenalis was demonstrated for humans. Giardiasis is still a public health problem in the 21st century, particularly in young children living in areas with low hygiene standards.

The raccoon roundworm (Baylisascaris procyonis) was introduced to Europe by its final host, the North American raccoon (Procyon lotor), which has been spreading uncontrollably there since the early 20th century. The raccoon is gaining importance due to the spread of the raccoon roundworm, which is pathogenic to humans and can cause severe disease through oral ingestion of infectious egg stages. Totally, 146 raccoons from central and western Germany were examined for B. procyonis via necropsy. In addition, an extensive literature search was conducted on the occurrence of B. procyonis in Europe. Of the 146 raccoons examined in this study, 66.4% were infected with B. procyonis: 77.4% in Hesse (n = 84), 51.1% in Thuringia (n = 45), and 52.9% in North Rhine-Westphalia (n = 17). The literature review revealed the presence of B. procyonis in wild raccoons in nine European countries. In three additional countries, infections were detected in raccoons or other animal species in captivity. The studies show a steady expansion of the distribution area, which is probably underestimated due to insufficient or absent data collection. Five animal species have been identified as paratenic/accidental hosts in Europe, with all infections documented in zoos/animal husbandry. There is a lack of data on paratenic hosts in the wild in Europe. There are three documented cases of Baylisascariasis in Europe. The results of the present study highlight the need for further research into B. procyonis in Europe, particularly in relation to ongoing urbanization and growing raccoon populations.

The Asian fish tapeworm (AFT), Schyzocotyle acheilognathi, is a highly invasive and pathogenic parasite of freshwater fishes, present on all continents except Antarctica. Globally, 310 + definitive fish host species have been recorded, with Mexico showing the highest number of reports. Here, we summarize the current knowledge about the biology, distribution, and ecological determinants of this parasite, highlighting key knowledge gaps that could guide future research. Considering Mexico has quite comprehensive records of this parasite (both in host and geographical terms), we propose that this country can be considered as a large-scale ecological laboratory to investigate the environmental variables associated with the parasite's dispersion capabilities in different geographic areas, potentially providing clues on the (unexplored) paths followed by this extremely successful invasive parasite. Using published parasitological data, we implemented exploratory analyses of ecological and environmental parameters to identify factors associated with the occurrence of S. acheilognathi. Temperature, precipitation, and elevation emerged as potential drivers of its distribution, providing a basis for ecological niche modeling and for predicting future range expansions under climate change scenarios. Despite its extensive host range, S. acheilognathi exhibits low genetic diversity-an intriguing feature that may underlie its ecological plasticity and invasive success. We also discuss the growing potential of omics and environmental DNA tools to advance non-destructive detection, clarify host-parasite dynamics, and uncover molecular mechanisms underlying host adaptation and invasion. Integrating these ecological and genomic perspectives will be essential to understand the evolutionary ecology of S. acheilognathi and to anticipate its impacts on freshwater biodiversity in an era of global change.

Leishmaniasis is a vector-borne disease caused by Leishmania protozoa, transmitted through infected female phlebotomine sandflies. Cutaneous leishmaniasis (CL), its most common form, causes considerable morbidity, particularly among Colombian military personnel in endemic areas. Although meglumine antimoniate (MA) remains the first-line treatment, increasing reports of therapeutic failure (TF) raise concerns about its efficacy and highlight the need to identify associated risk factors. The objective of this study was to identify risk factors linked to MA treatment outcomes in Colombian soldiers with CL and to characterise the Leishmania species involved and their geographic distribution. A total of 128 soldiers diagnosed with CL (2018-2019) were followed for treatment response. Sociodemographic, clinical and lesion data were collected. Leishmania species were identified through HSP70 and MPI gene barcoding, and geographic origins were mapped. Selected isolates from TF patients underwent in vitro susceptibility testing to MA. The cure proportion was 67.9%, with TF in 32%. Factors significantly associated with TF included previous infections (p = 0.001), prior MA use (p = 0.000), lymphadenopathy (p = 0.008) and lesion type (p = 0.002). Multivariate analysis identified previous treatment (p = 0.000), lesion size and infections acquired in the Orinoquía (p = 0.013) and Pacific (p = 0.014) regions as risk factors. L. (V.) braziliensis predominated, especially in Orinoquía and Amazon regions; L. (V.) panamensis was widespread, and L. (L.) mexicana appeared only in the Andean region. In vitro resistance to MA was not observed in analysed isolates; thus, this factor does not appear related to TF. TF is linked to specific clinical and epidemiological variables, supporting their integration into patient monitoring during MA therapy. Clinical trial number: not applicable.

Cryptosporidium spp. and Giardia duodenalis are major enteric pathogens in neonatal calves, contributing to gastrointestinal disease and raising concerns due to their zoonotic potential. Despite their global distribution, little is known about their occurrence and genetic diversity in insular regions such as the Azores archipelago (Portugal). This study investigated the prevalence, distribution, genetic diversity, and farm-level risk factors associated with these parasites in dairy calves from Terceira Island. Fecal samples (n = 142) from 28 farms were examined by microscopy, direct immunofluorescence assay (DFA), and PCR targeting multiple loci (SSU rRNA, gp60, LSU rRNA for Cryptosporidium spp.; gdh, bg, tpi for G. duodenalis). Sequencing enabled molecular identification of species, genotypes, and assemblages. Farm management data were collected by standardized questionnaires, and spatial analysis used farm location. Overall, 65.5% (93/142) of calves were infected with at least one parasite, with Cryptosporidium spp. and Giardia spp. detected in 42.3% (60/142) and 44.4% (63/142) of samples, respectively. Mixed infections occurred in 21.1% (30/142) of calves. Molecular characterization identified C. parvum (subtype IIaA15G2R1), C. bovis, and C. ryanae, as well as G. duodenalis assemblage E (predominant) and assemblage A (rare). Spatial mapping showed Cryptosporidium spp. to be widespread, while Giardia spp. displayed localized clusters. Use of paromomycin and higher hygiene scores were associated with reduced Giardia risk, whereas no risk factors were found for Cryptosporidium. These findings provide novel insights into protozoan infections in calves in the Azores and highlight the value of integrating molecular, spatial, and management data for targeted control strategies.

To investigate the effects of Echinococcus granulosus sensu stricto (E. granulosus s.s.) reproduction-associated protein EGr_09888 on the development of E. granulosus s.s. protoscoleces (PSCs) in vitro. SWISS-MODEL, Netphos3.1, and PyMOL bioinformatics analysis software, along with subcellular localization prediction, were used to analyze the structure, phosphorylation sites, epitopes, and distribution of the EGr_09888 protein. The recombinant plasmid pET30a-EGr_09888 was constructed for protein expression and purification, and New Zealand white rabbits were immunized with the recombinant protein. An indirect ELISA method was used to determine serum IgG levels, through Western blotting to verify immune specificity and different stages worm protein extracts EGr_09888 protein expression. The distribution of EGr_09888 in PSCs, adult worms and gravid segments was analyzed by immunofluorescence staining. PSCs cultured in vitro for 3, 6, and 10 weeks were treated with rabbit anti-EGr_09888 high-titer immune serum for 6 days and then their survival rate and the gene expression of EGr_09888 in the PSCs was analyzed. The result revealed that the EGr_09888 protein has diverse secondary-structure amino acid proportions, and its SWISS-MODEL-predicted tertiary structure is reliable, containing 54 potential phosphorylation sites. It has B- and T-cell epitopes at amino acids (aa) 25-44 and 166-185, shows immunogenic potential, and is localized mainly in the cytoplasm. Induced expression of the recombinant EGr_09888 protein (27 kDa) resulted in rabbit anti-EGr_09888 serum with a potency greater than 1:160000. Immunoblotting revealed that the rabbit anti-EGr_09888 serum could specifically bind to the recombinant EGr_09888 protein. And the expression level of EGr_09888 protein was higher in adult worm protein extracts (P ≤ 0.001), Immunofluorescence staining analysis revealed that EGr_09888 was localized mainly within the uterus of the gravid segment of E. granulosus s.s adult worms. After 6- and 10-week-old PSCs were treated with rabbit anti-EGr_09888 serum, the survival rate and relative PSC EGr_09888 expression level were significantly reduced (P < 0.0001). This study revealed that EGr_09888, a reproduction-related protein in E. granulosus s.s., has potential as a candidate vaccine for definitive hosts.

Epigenetic inhibitors targeting histone methyltransferases (HMTs) have been proven to be promising for blood protozoan treatment. However, little is known about the effects of HMT inhibitors on Babesia parasites. Here, in vitro and in vivo drug tests were performed to evaluate the efficacy of several compounds targeting various HMTs for Babesia treatment. Their cytotoxicity to MDOK cells was also assessed. Among these compounds, furamidine demonstrated outstanding activity in vitro at the nanomolar level (IC₅₀s of 0.03 ± 0.55, 0.02 ± 0.50, and0.02 ± 0.76 μM at 48, 72, and 96 h, respectively). Furthermore, the IC₅₀ of furamidine on MDOK cells was ~ 100 μM after 24 h, ~ 45 μM after 48 h and ~ 40 μM after 72 h. The therapeutic index of furamidine was greater than 1,500. In addition, furamidine effectively inhibited the growth of B. duncani and B. microti in hamsters and BALB/c mice. Furthermore, furamidine was demonstrated high in vivo safety. These findings suggest that furamidine could be an effective alternative drug for treating babesiosis.

This study aimed to develop and evaluate a nanoemulsion containing spiramycin and curcumin (NE-CS) to enhance these compounds' bioavailability and efficacy against acute and chronic toxoplasmosis in mice. Nanoemulsion containing spiramycin and curcumin (NE-CS), spiramycin nanoemulsion (NE-Spi), and a nanoemulsion without the drug (NE) were prepared via spontaneous emulsification and characterized for particle size and zeta potential. Their in vitro activity was tested against tachyzoites of T. gondii, RH strain, at different concentrations (250, 125, 62.5, and 31.25 µg/ml) and time points (30, 60, 90, and 120 min). In vivo, BALB/c mice infected with RH and Tehran strains were treated with NE-CS (25 mg/kg/day curcumin + 50 mg/kg/day spiramycin), NE-Spi (50 mg/kg/day), S-Spi, and NE, with infected/untreated mice as controls. Survival time, tachyzoite counts in peritoneal fluid (acute phase), and number and size of tissue cysts (chronic phase) were assessed microscopically. NE-CS significantly decreased the intracellular multiplication of T. gondii tachyzoites (5 ± 2.78 × 10⁴) compared with that of the infected/untreated group (3509 ± 435.39 × 10⁴). Oral administration of NE-CS improved therapeutic outcomes in vivo, prolonged survival time in mice (13 days), reduced parasitemia, and decreased both the number (43 ± 5.78) and size (4 ± 1.11 µm) of brain cysts compared to the infected/untreated group (380 ± 17.22 and 112.8 ± 8.28 µm, respectively). This study demonstrated the in vitro efficiency of nanoemulsion co-delivery of curcumin and spiramycin for increasing tachyzoite death, and indicated the possibility of NE-CS and NE-Spi for treating acute and chronic toxoplasmosis in murine models. However, further investigations are needed to confirm their safety and effectiveness across broader models.