Ticks are important vectors of pathogens with substantial medical and veterinary relevance, a threat that may be further increased with the spread of invasive tick species. Reliable tick identification is relevant for accurate diagnostic elucidation of transmission pathways, and the development of targeted surveillance strategies and risk assessments. A standardized, rapid, and cost-effective identification workflow that can be implemented across laboratories is needed. Previous studies have shown that MALDI-TOF MS is a promising, objective, and economical approach for tick identification. However, the methodology remains insufficiently standardized and is not yet routinely applied for vector identification. The aim of this study was therefore to optimize MALDI-TOF MS-based tick identification for routine use in diagnostic laboratories. A simplified and standardized protocol for protein extraction from whole tick legs via brief incubation in 70% formic acid is presented. This protocol provides a robust basis for the development of a curated MALDI Biotyper® reference library, enabling reliable, expert-independent tick identification and supporting epidemiological surveillance of vectors and vector-borne pathogens.

Ixodes ricinus is the most widespread tick species in Europe, parasitizing a broad range of vertebrate hosts, including reptiles. However, the role of lizards in the ecology of tick-borne pathogens remains poorly understood. This study investigated tick infestation levels and the occurrence of tick-borne pathogens in I. ricinus feeding on European common lizards (Zootoca vivipara louislantzi) in the central Pyrenees, Spain. A total of 137 lizards were captured in summer and spring of 2024 at two sites (~ 1700 m.a.s.l.). Tick infestation prevalence was 98.5% and a mean abundance of 5.8 ± 7.0 ticks. Infestation was significantly higher in males, adults, and during spring. Molecular screening of 525 ticks (188 pools) using real-time and conventional PCR protocols detected Rickettsia spp. DNA in 15.4% pools, with an overall minimum infection rate (MIR) of 5.52%, with stage-specific MIRs of 4.79% in larvae and 7.81% in nymphs. Sequencing of 14 amplicons identified Rickettsia helvetica (n = 11) and Rickettsia monacensis (n = 3). Babesia DNA was detected at low prevalence (MIR: 0.38%) and sequences clustered within the Babesia divergens-Babesia capreoli complex. No Borrelia burgdorferi sensu lato and Anaplasma phagocytophilum DNA was detected. Our findings show that lizards can sustain high levels of I. ricinus infestation, constituting a reliable bloodmeal source for ticks infected with Rickettsia and Babesia in the mountain ecosystems of the Pyrenees. Although the lizard's role in pathogen transmission remains to be clarified, its consistent exposure to immature ticks highlights its potential value as a sentinel species for monitoring tick-borne pathogen circulation in high-altitude environments.

Theileria annulata, an apicomplexan parasite, causes lymphoproliferative disease in cattle and threatens the bovine industry in tropical and subtropical regions. To clarify life-cycle mechanisms and parasite-host interactions, we conducted high-resolution Orbitrap proteomic and phosphoproteomic analyses of the schizont and piroplasm stages. In total, we confidently identified and quantified 2,093 proteins; among these, 459 proteins were observed in a phosphorylated state, comprising 5,069 distinct phosphorylation sites. Functional enrichment analysis of differentially abundant proteins indicated stage-associated remodeling of genetic information processing, carbohydrate, lipid, and amino-acid metabolism, and core cellular processes. Stage-associated proteins were linked to host-parasite interaction, mitochondrial function, and metabolic adaptation. Schizonts showed broader proteomic and phosphorylation profiles consistent with higher biosynthetic and energy demands. In contrast, piroplasms exhibited a more restricted proteomic profile associated with erythrocyte adaptation and invasion-related functions. Together, these stage-resolved datasets provide a reference for proteome and phosphoproteome remodeling across development and prioritize candidate stage-associated proteins and phosphosites for future functional validation.

Fish serve as hosts to a wide range of parasites, which can affect them in many ways, including their survival, growth, and foraging behavior. The highly threatened unionid mussels have an ectoparasitic life stage on the gills, skin, or fins of fish. Here, we compared prey handling time and growth between groups of brown trout (Salmo trutta) that were infested and non-infested with glochidia larvae of the freshwater pearl mussel (Margaritifera margaritifera). In a prey handling test, individual trout were presented with one large prey (maggot) and one small prey (Gammarus pulex) daily over eight days. Compared to non-infested trout, prey handling time was longer for infested trout feeding on larger but not on smaller prey. In a growth test, where trout were fed daily with minced calf liver over nine weeks, the growth rate was lower for infested than for non-infested trout. Moreover, the growth rate was higher for infested trout from which glochidia were expelled compared to trout from which glochidia were not expelled. We suggest that glochidia infestation can increase prey handling time of fish, ultimately reducing fish growth, but that slow prey handling may be transitory for fish losing glochidia, and result in compensatory growth of the fish. Slow prey handling, in combination with a negative effect of glochidia infestation on food competition between infested and non-infested trout, may be reasons behind the lower growth of infested fish.

Baylisascaris species parasitizing skunks have received limited attention compared to the well-characterized raccoon roundworm (B. procyonis). We present the first complete mitochondrial genome of a Baylisascaris sp. collected in Kansas, United States, from a striped skunk (Mephitis mephitis). We morphologically identified the nematode as Baylisascaris sp., extracted DNA, sequenced it on the Illumina platform, and de novo assembled the complete mitochondrial genome. The complete mitochondrial genome was 14,752 bp, consisting of 12 protein-coding genes, 2 rRNAs, and 22 tRNAs. The genome had a significant AT-skew (70.5%). The mitochondrial genome obtained in this study was 98% identical to that of B. procyonis and grouped most closely to B. procyonis with 100% bootstrap support in a phylogenetic analysis of ascarid nematodes. The mitochondrial genome generated in this study (GenBank accession no. PZ025724) will benefit future studies in diagnostic epidemiology and systematics and has implications for public health.

Ascaris lumbricoides remains one of the most prevalent soil-transmitted helminths worldwide, with ongoing transmission in endemic regions despite long-standing control programs. This study investigated the genetic diversity, population structure, and benzimidazole resistance of A. lumbricoides across three endemic regions of Thailand using mitochondrial (cox1 and nad1) and nuclear (β-tubulin) markers. Haplotype network analysis identified 13 haplotypes within the Thailand dataset, including three newly identified haplotypes, indicating measurable genetic diversity at the local scale. When analyzed in a global context incorporating reference sequences, substantially higher haplotype diversity was observed, reflecting broad genetic diversity across geographic regions. Despite this diversity, no clear geographic structuring was detected among Thai populations, suggesting ongoing gene flow and population connectivity. Phylogenetic analyses further demonstrated that all isolates clustered within a single major lineage and shared haplotypes with Ascaris suum (infecting pig), supporting genetic overlap and potential zoonotic transmission. Analysis of the β-tubulin gene revealed exclusively wild-type alleles at codons 167, 198, and 200, with no evidence of mutations associated with benzimidazole resistance. Overall, this study demonstrates measurable genetic diversity in Thailand's A. lumbricoides populations, with no evidence of clear geographic structuring. These findings provide baseline molecular data to support future surveillance of transmission dynamics and anthelmintic resistance.

Chicken coccidiosis is a ubiquitous and economically significant disease that causes substantial production losses in the poultry industry. It is caused by protozoan parasites of the genus Eimeria, which damage the intestinal epithelium, leading to diarrhoea, poor growth, and mortality. This study investigated the prevalence, risk factors, molecular diversity, and phylogenetic relationships of Eimeria infections in commercial poultry farms in Bangladesh. A total of 350 fresh fecal samples were collected from seven major poultry-producing regions and screened microscopically for oocysts. Farm-level data were obtained through structured interviews to assess associated risk factors. Samples with high oocyst loads were subjected to molecular analysis targeting the internal transcribed spacer 1 region, followed by Sanger sequencing and phylogenetic reconstruction. The overall prevalence was 85.14%, with regional variation ranging from 61.22% in Sylhet to 100% in Joypurhat. Significant associations (p < 0.05) were observed with bird type, prior coccidiosis exposure, drinking water source, anticoccidial used, and veterinary support. Sequence analysis confirmed the presence of all seven recognized Eimeria species, showing 98.05-100% similarity with reference sequences. Mixed infections were highly prevalent (97.57%), with multiple species detected per sample. Phylogenetic reconstruction showed that the study isolates consistently grouped with their corresponding reference taxa, supported by strong bootstrap values, and confirming accurate species identification and genetic relatedness. In conclusion, detection of all Eimeria species, together with the high burden of mixed infections and the influence of modifiable management factors, underscores the necessity for improved and integrated control measures for coccidiosis in commercial poultry systems in Bangladesh. Clinical trial number: not applicable.

Toxoplasmosis is a globally prevalent parasitic disease with significant therapeutic limitations, especially in vulnerable populations. This scoping review assesses the efficacy of quinolones against Toxoplasma gondii in vitro and in vivo. PubMed, ScienceDirect, Web of Science, Embase, Scopus, ProQuest, and Google Scholar were searched from inception to August 2024. Original English-language studies evaluating quinolone effects on T. gondii were included. Screening and data extraction followed PRISMA 2020 guidelines. Of 5,252 initial records, 29 studies were shortlisted for final qualitative synthesis. In vitro analysis revealed a stark dichotomy: while clinical fluoroquinolones such as ciprofloxacin (IC50 = 3.44-20 µM) possessed weak-to-moderate activity, experimental scaffolds, particularly Hydroxyquinolone derivatives (e.g., Compound A, IC50 = 0.0004 μM) and endochin-like quinolones (ELQs) (e.g., ELQ-316, IC50 = 0.000007 μM) achieved sub-nanomolar potency by inhibiting the mitochondrial electron transport chain. Structural optimization was essential; for example, adamantane-conjugated ciprofloxacin (Adam-Cipro) was 31-fold more potent than the parent drug (IC50 = 0.64 µM vs. 20 µM). Combination regimens (e.g., gatifloxacin-pyrimethamine) maximized efficacy while also lowering resistance risks. Novel compounds such as ELQ-316 (0.08 mg/kg) decreased brain cyst burden by up to 88% in chronic models and provided complete protection in acute models. Translational challenges were identified, including the failure of decoquinate (DCQ) to suppress vertical transmission in pregnancy models and the emergence of resistance to ELQ-316. Key research gaps persist: the activity of quinolones against latent bradyzoites, efficacy in immunocompromised hosts, and safety in children and pregnant women remain unexplored. This review demonstrates that while conventional clinical quinolones are suboptimal against T. gondii, structure-optimized quinolones targeting the parasite mitochondria can yield outstanding potency. Efficacy is determined by precise structure activity relationships (particularly at the C-7 position) and advanced drug delivery systems. Despite ongoing translational challenges such as bioavailability optimization, tissue penetration barriers, and resistance management new quinolone compounds and combination regimens hold great promise as anti-Toxoplasma drugs.

Post-mortem myoliquefaction, commonly referred to as 'jelly flesh', is associated with infection by myxozoan parasites of the genus Kudoa, particularly Kudoa thyrsites; the effects of infections can render fish fillets unusable in food preparation. Although the parasite has been documented in Atlantic mackerel (Scomber scombrus) across parts of the Northeast Atlantic, its presence in mackerel landed in Ireland has not been previously confirmed. In this study, mackerel obtained from commercial landings were screened for signs of post-mortem myoliquefaction. Three individuals displaying characteristics of softening of the musculature were examined using light microscopy and molecular analysis. Microscopic examination revealed numerous spores consistent with Kudoa-like morphology. Sequencing of the amplified region confirmed the presence of K. thyrsites in all three samples. The sequences showed a 100% match with K. thyrsites isolates previously reported from Atlantic mackerel and other host species in the Northeast Atlantic. Moreover, phylogenetic analysis placed the Irish isolate within the expected Atlantic sub-clade. As molecular testing was limited to visibly affected fish, the prevalence of K. thyrsites infection in the mackerel population could not be estimated, highlighting the need for continued monitoring of the parasite in Irish waters to better understand its distribution and potential economic implications for the Northeast Atlantic fishery.

The Anthropocene is the most recent period in Earth's history and is characterized by humankind-driven alterations to all ecosystems. Climate change, pollution, overfishing, invasive species and habitat degradation continue to reshape aquatic ecosystems, and like all living organisms in our changing world, parasites are likely to be affected at different levels. This Collection features research and review papers on some of these topics: parasites co-introduced with their fish hosts illustrate that biological invasions must be studied case-by-case, as some fish hosts lose their parasites upon translocation (enemy release), some pass them on to the invaded ecosystems (overspill) and some acquire -and sometimes amplify- native parasites (spillback), regardless of the time frame, as illustrated in studies of parasites co-introduced from 150 to 15 years ago. Biological information is a powerful tool to predict and prevent the spread of invasive/pathogenic species, and while this Collection provides baseline data for several introduced parasites, it also features practical proposals to control pathogenic/zoonotic species. Climate change and habitat alterations also exert a powerful influence on parasite populations - which likewise, must be studied individually, as some species decline and/or modify their distribution markedly (leading to hybridization and potentially speciation of previously separated taxa), while others benefit from the modified environment, are able to invade new hosts and/or become more infective or pathogenic. Parasites play different ecosystemic roles and are finely-tuned bioindicators of anthropogenic impact in freshwater ecosystems, and this Collection highlights the notion that they should be integrated in public health and conservation initiatives.

Human activities have profoundly altered freshwater ecosystems, reshaping host-parasite dynamics with sometimes far-reaching ecological and public health consequences. Based on the examples of stream degradation and restoration, dam construction, agriculture, and urbanization, this review synthesizes how habitat alteration influences parasite communities in freshwater systems. Restoration efforts, such as those in Germany's Emscher River, demonstrate partial recovery of parasite diversity, though persistent stressors often favour generalist taxa with simple life cycles, reflecting incomplete ecosystem recovery. Dams and reservoirs, by contrast, frequently amplify parasite transmission by creating lentic habitats that aggregate hosts and vectors, increasing risks for diseases such as schistosomiasis and malaria. Agricultural land use further complicates these dynamics: while eutrophication and irrigation can boost trematode transmission, agrochemicals and habitat fragmentation may depauperate parasite communities or disrupt complex life cycles. Additionally, urbanization-related stressors, such as pollutants and artificial light, can suppress sensitive parasites while benefiting those adapted to disturbed environments. Our review demonstrates that, under habitat alteration, freshwater parasites fulfil multiple roles: they constitute a component of the impacted biodiversity, serve as indicators of ecosystem health, and influence disease risk, with their responses governed by life cycle complexity, host specificity, and environmental resilience. These findings underscore the need for integrated management strategies that account for parasites in conservation and public health planning.

Cystic echinococcosis (CE) remains a significant public health burden in Iran, with humans serving as accidental dead-end hosts. This study assesses historical CE prevalence trends and projects future human CE burden under targeted intervention scenarios using mathematical modeling. We developed a dynamic Susceptible-Exposed-Inected-Recovered (SEIR) transmission model of CE in Iran, calibrated to historical human prevalence data (1997-2023). Univariate and bivariate sensitivity analyses were conducted to evaluate the influence of key parameters. Model projections to 2040 evaluated four intervention scenarios: a baseline scenario and three alternatives, targeting reductions in exposure rates and increases in case detection rates. Human CE prevalence declined from 3.90% (1997) to 2.20% (2023), representing a 43.49% reduction. Projected trends indicate further decline to 1.37% by 2040 (37.79% reduction from 2023). The 40% exposure reduction scenario achieved the lowest prevalence (1.16% in 2040; 47.31% reduction), while the combined 20% exposure reduction plus 20% detection rate increase scenario yielded 1.27% (42.54% reduction). Crucially, enhanced detection rate reduced long-term prevalence by shortening time-to-diagnosis (time from infection to diagnosis), accelerating case resolution without altering transmission dynamics. To accelerate Iran's successful CE control program toward timely elimination, a decisive strategy to reduce transmission at its source is paramount. Our modeling identifies a 40% reduction in the exposure rate as the most effective intervention to minimize prevalence by 2040. Enhancing early detection provides synergistic benefits, but targeted veterinary and environmental control must be the priority for a rapid and equitable outcome.

Interactions between wild deer and domestic livestock are increasingly common in southeastern Australia, but contemporary information on gastrointestinal nematodes infecting wild deer remains limited. In this study, nemabiome metabarcoding of the internal transcribed spacer 2 (ITS-2) region of ribosomal DNA was used to characterise strongyle communities in wild deer from Victoria, Australia. A total of 194 faecal samples from three deer species - sambar (Rusa unicolor), fallow (Dama dama) and hog deer (Axis porcinus) - were analysed using Illumina amplicon sequencing. Strongyle DNA was detected in 104 samples, revealing eleven taxa. Eight species (Cooperia oncophora, Haemonchus spp., Ostertagia ostertagi, O. leptospicularis, O. radiatum, Trichostrongylus axei, T. colubriformis and T. vitrinus) are commonly associated with domestic ruminants, whereas the cervid-associated strongyle Spiculopteragia asymmetrica was the most frequently detected taxon. Deer sampled near farmland harboured significantly greater strongyle diversity than those from more remote locations. Overlapping parasite taxa were also detected in co-grazing deer and cattle. These findings indicate that wild deer in southeastern Australia harbour diverse strongyle communities and highlight the potential for overlapping parasite assemblages at the wildlife-livestock interface.