During the investigation of parasitic pathogens of Mytilus coruscus, infection of a Perkinsus-like protozoan parasite was detected by alternative Ray's Fluid Thioglycolate Medium (ARFTM). The diameter of hypnospores or prezoosporangia was 8–27 (15.6 ± 4.0, n = 111) μm. The prevalence of the Perkinsus-like species in M. coruscus was 25 and 12.5% using ARFTM and PCR, respectively. The ITS1-5.8S-ITS2 fragments amplified by PCR assay had 100% homology to that of P. beihaiensis, suggesting that the protozoan parasite was P. beihaisensis and M. coruscus was its new host in East China Sea (ECS). Histological analysis showed the presence of trophozoites of P. beihaiensis in gill, mantle and visceral mass, and the schizonts only found in visceral mass. Perkinsus beihaiensis infection led to inflammatory reaction of hemocyte and the destruction of digestive tubules in visceral mass, which had negative effect on health of the farmed M. coruscus and it deserves more attention.

Avian blood parasites play a crucial role in wildlife health and ecosystem dynamics, exhibiting heterogeneous spatial distribution influenced by various factors. Although factors underlying heterogeneity in infection with blood parasites have been explored in many avian hosts, their importance in the context of host species and the parasite taxon remains poorly understood, particularly in cohabiting host species. Using next-generation sequencing for parasite screening, we investigate the association between Haemoproteus, Plasmodium and Trypanosoma infections in relation to individual parameters, host densities and landscape features in 3 cavity-nesting passerines: great tit (Parus major), blue tit (Cyanistes caeruleus) and collared flycatcher (Ficedula albicollis) in a highly fragmented forest habitat. Overall, Haemoproteus infections predominated, followed by Plasmodium and Trypanosoma, with great tits most and collared flycatchers least parasitized. There were no common patterns across host species in the probability of infection with locally transmitted parasites from each genus. Specifically, in all cases, the effect of particular parameters, if present, was observed only in 1 host species. Body condition influenced Haemoproteus and Plasmodium infections differently in tits. Host density, whether own species or all pooled, explained Haemoproteus infections in great tits and collared flycatchers, and Plasmodium in great tits. Landscape metrics, such as moisture index and distance to coast edge and pastures, affected infection probability in specific host–parasite combinations. Relative risk maps revealed infection risk gradients, but spatial variation repeatability over time was low. Our study highlights the complex dynamics of avian blood parasites in multi-host systems, shedding light on host–parasite interactions in natural ecosystems.

Emprostiotrema contains just 3 species: E. fusum, E. kuntzi and E. sigani. As adults, all 3 species infect rabbitfishes (Siganidae: Siganus). New collections from 11 species of Siganus from northern Australia, Indonesia, New Caledonia, French Polynesia, Palau and Japan enabled an exploration of species composition within this genus. Phylogenetic analyses demonstrate a deep distinction between 2 major clades; clade 1 comprises most of the sequences of specimens from Australia as well as all of those from Japan, Palau and New Caledonia and clade 2 comprises all sequences of specimens from French Polynesia, 2 sequences from Australia and the single sequence from Bali. In all analyses, both major clades have genetic structuring leading to distinct geographic lineages. Morphologically, specimens relating to clades 1 and 2 differ but overlap in body shape, oral sucker and egg size. Principle component analysis shows a general (but not complete) separation between specimens relating to the 2 clades. We interpret the 2 clades as representing 2 species: clade 1 is identified as E. fusum and is reported in this study from 10 species of siganids from Australia, Japan, Palau and New Caledonia; clade 2 is described as E. gotozakiorum n. sp., for all specimens from French Polynesia and rare specimens from Australia and Indonesia. We recognize E. sigani as a junior synonym of E. fusum. Although species of Emprostiotrema occur widely in the tropical Indo-Pacific, they have not been detected from Ningaloo Reef (Western Australia), the southern Great Barrier Reef or Moreton Bay (southern Queensland).

Aurora kinases (AURK) play a central role in controlling cell cycle in a wide range of organisms. They belong to the family of serine-threonine kinase proteins. Their role in the cell cycle includes, among others, the entry into mitosis, maturation of the centrosome and formation of the mitotic spindle. In mammals, 3 isoforms have been described: A, B and C, which are distinguished mainly by their function throughout the cell cycle. Two aurora kinase coding sequences have been identified in the transcriptome of the cattle tick Rhipicephalus microplus (Rm-AURKA and Rm-AURKB) containing the aurora kinase-specific domain. For both isoforms, the highest number of AURK coding transcripts is found in ovaries. Based on deduced amino acid sequences, it was possible to identify non-conserved threonine residues which are essential to AURK functions in vertebrates and which are not present in R. microplus sequences. A pan AURK inhibitor (CCT137690) caused cell viability decline in the BME26 tick embryonic cell line. In silico docking assay showed an interaction between Aurora kinase and CCT137690 with exclusive interaction sites in Rm-AURKA. The characterization of exclusive regions of the enzyme will enable new studies aimed at promoting species-specific enzymatic inhibition in ectoparasites.

Host–bacterial communities (microbiomes) are influenced by a wide range of factors including host genotype and parasite exposure. However, few studies disentangle temporal and host-genotype-specific variation in microbiome response to infection across several host tissues. We experimentally exposed the freshwater crustacean Daphnia magna to its fungal parasite Metschnikowia bicuspidata and characterized changes in host–bacterial communities associated with the parasite's development within the host. We used 16S rRNA gene sequencing to assess bacterial communities of the host (a) 24 h (‘initial parasite exposure’) and (b) 10 days (‘successful infection’) after exposure to a standard dose of M. bicuspidata spores, in host guts, body tissue (excluding guts) and whole individuals. We also investigated whether bacterial community responses to parasite exposure varied by host genotype.

Parasite exposure did not immediately alter host gut bacterial communities, but drove host-genotype-specific changes in the bacterial community composition of whole individuals. We validated that these changes were not driven by shifts in bacterial communities of the culturing medium, due to the addition of the parasite spore solution. Successful infection (i.e. the proliferation of M. bicuspidata spores in the host body) reduced alpha diversity and shifted abundance of dominant bacterial orders in the gut. Moreover, it induced a host-genotype-specific changes in body bacterial community composition. Overall, bacterial community responses to parasite exposure and subsequent infection are complex: they occur in a host-genotype-dependent manner, differentially at distinct timepoints after parasite exposure, and in specific host tissue.

Haemoproteus bobricklefsi sp. nov. (Haemosporida, Haemoproteidae) was found in the dunnock Prunella modularis and represents the first blood parasite described in accentor birds of the Prunellidae. The description is based on the morphology of blood stages and includes information about a barcoding segment of the mitochondrial cytochrome b gene (lineage hDUNNO01) and the full mitochondrial genome, which can be used for identification and diagnosis of this infection. The new parasite can be readily distinguished from described species of haemoproteids parasitizing passeriform birds due to markedly variable position of nuclei in advanced and fully grown macrogametocytes. Illustrations of blood stages of the new species are given, and phylogenetic analyses based on partial mitochondrial cytochrome b gene sequences and the full mitochondrial genome identified the closely related lineages. DNA haplotype networks showed that transmission occurs in Europe and North America. This parasite was found in the dunnock in Europe and several species of the Passerellidae in North America. It is probably of Holarctic distribution, with the highest reported prevalence in the UK. The parasite distribution seems to be geographically patchy, with preference for areas of relatively cool climates. Phylogenetic analysis suggests that H. bobricklefsi sp. nov. belongs to the Parahaemoproteus subgenus and is probably transmitted by biting midges belonging to Culicoides (Ceratopogonidae). The available data on molecular occurrence indicate that this pathogen is prone to abortive development, so worth attention in regard of consequences for bird health.

Ticks prefer specific feeding sites on a host that are influenced by host–tick and tick–tick interactions. This study focused on the spatiotemporal distribution of ticks in Hokkaido sika deer, an important tick host in Hokkaido, Japan. Tick sampling was performed on the sika deer in the Shiretoko National Park between June and October 2022. Ticks were collected from 9 different body parts of the deer to compare their attachment site preferences. Interspecific and intraspecific relationships among ticks were examined using co-occurrence analysis. The collected ticks were nymphal and adult stages of 4 species: Ixodes ovatus, Ixodes persulcatus, Haemaphysalis japonica and Haemaphysalis megaspinosa. Seasonal variations in tick burden were observed, with I. persulcatus and I. ovatus peaking in June and declining towards October; H. japonica showing low numbers in July and August and increasing from September; and H. megaspinosa appearing from September onwards with little variation. Attachment site preferences varied among species, with a significant preference for the pinna in I. ovatus and I. persulcatus. Haemaphysalis japonica was mainly found on the body and legs between June and August, and shifted to the pinna from September. Haemaphysalis megaspinosa showed a general preference for areas other than the legs. Co-occurrence analysis revealed positive, negative and random co-occurrence patterns among the tick species. Ticks of the same genus and species exhibited positive co-occurrence patterns; I. ovatus showed negative co-occurrence patterns with Haemaphysalis spp. This study revealed the unique attachment site preferences and distinct seasonal distributions of tick species in the Hokkaido sika deer.

This study investigates the molecular intricacies of the transmembrane protein TSP11 gene in Echinococcus strains isolated from livestock and patients in Yunnan Province afflicted with Echinococcus granulosus (E. granulosus) between 2016 and 2020. Gene typing analysis of the ND1 gene revealed the presence of the G1 type, G5 type and untyped strains, constituting 52.4, 38.1 and 9.5%, respectively. The analysis of 42 DNA sequences has revealed 24 novel single nucleotide polymorphic sites, delineating 11 haplotypes, all of which were of the mutant type. Importantly, there were no variations observed in mutation sites or haplotypes in any of the hosts. The total length of the TSP11 gene's 4 exons is 762 bp, encoding 254 amino acids. Our analysis posits the existence of 6 potential B-cell antigenic epitopes within TSP11, specifically at positions 49-KSN-51, 139-GKRG-142, 162-DNG-164, 169-NGS-171, 185-DS-186 and 231-PPRFTN-236. Notably, these epitopes exhibit consistent presence among various intermediate hosts and haplotypes. However, further validation is imperative to ascertain their viability as diagnostic antigens for E. granulosus in the Yunnan Province.

Avian nests often contain aromatic plant fragments, which has led to propose among others that they repel ectoparasites or vectors of blood parasites (‘nest protection hypothesis’). To date, the relationship between secondary plant provisioning and the parent's blood parasites remains unexplored. We investigated whether the presence of secondary plants in nests during different reproductive stages (before incubation, during incubation and nestling period) was associated with the presence of nest-dwelling ectoparasites and females’ blood-parasite infections in blue tits (Cyanistes caeruleus) during chick rearing. In this species, females are highly exposed to parasites, particularly at the beginning of the breeding season, since they build the nest and incubate alone. They also brood the nestlings while the male assists with provisioning. We found that females that provided fewer plants before incubation were more likely to be infected by Plasmodium. Specifically, Females that did not provide Achillea herbs before incubation were more likely to be infected by both Plasmodium and Haemoproteus, reinforcing the ‘nest protection’ hypothesis. Thus, secondary plants may create an early environment that masks the odour of hosts or repels vectors. Surprisingly, the presence of Lavandula during the nestling period was positively related to Leucocytozoon infection. Given its fastest development among haemosporidians, we speculate that Lavandula herbs are provided by females to reduce mother-to-offspring transmission or as a self-medication strategy. Finally, the number of plant fragments provided before incubation was negatively associated with the number of (Protocalliphora azurea) larvae, whereas there were no associations with the presence of mites (Dermanyssus gallinoides).

Ponto-Caspian gobies became highly abundant in many regions outside their native distribution range (e.g. in the Rhine River system). In the newly invaded habitats, the parasite communities of the invasive gobies are characterized by a lower species richness compared to their native range. Interestingly, acanthocephalans of the genus Pomphorhynchus are highly abundant, although they do not become mature and mostly remain encapsulated in the abdominal cavity as preadults. Thus, gobiids could either represent a dead-end host for Pomphorhynchus sp. declining its population (dilution effect) or act as a paratenic host that could increase the infection pressure if the infected gobies are preyed upon by appropriate definitive hosts (spill back). To determine which of the 2 scenarios the gobiids contribute to, we conducted 2 infection experiments using smaller and larger individuals of the definitive host chub (Squalius cephalus), infected with preadults of Pomphorhynchus sp. collected from the abdominal cavity of Neogobius melanostomus. The results showed that preadults were able to complete their development and mature in the definitive host with mean recovery rates of 17.9% in smaller and 27.0% in larger chubs. Successful infections were observed in 62.0% and 80.0% of the smaller and larger chubs, respectively. Our study demonstrated that gobies can theoretically serve as a paratenic host for acanthocephalans of the genus Pomphorhynchus, and that infection might spill back into the local fish community if infected gobies are preyed upon by suitable definitive hosts of Pomphorhynchus sp. such as large barbel or chub.

The 17-subunit RNA polymerase III (RNAP III) synthesizes essential untranslated RNAs such as tRNAs and 5S rRNA. In yeast and vertebrates, subunit C82 forms a stable subcomplex with C34 and C31 that is necessary for promoter-specific transcription initiation. Little is known about RNAP III transcription in trypanosomatid parasites. To narrow this knowledge gap, we characterized the C82 subunit in Trypanosoma brucei and Leishmania major. Bioinformatic analyses showed that the 4 distinctive extended winged-helix (eWH) domains and the coiled-coil motif are present in C82 in these microorganisms. Nevertheless, C82 in trypanosomatids presents certain unique traits, including an exclusive loop within the eWH1 domain. We found that C82 localizes to the nucleus and binds to RNAP III-dependent genes in the insect stages of both parasites. Knock-down of C82 by RNA interference significantly reduced the levels of tRNAs and 5S rRNA and led to the death of procyclic forms of T. brucei. Tandem affinity purifications with both parasites allowed the identification of several C82-interacting partners, including C34 and some genus-specific putative regulators of transcription. However, the orthologue of C31 was not found in trypanosomatids. Interestingly, our data suggest a strong association of C82 with TFIIIC subunits in T. brucei, but not in L. major.

Although 12 soft tick species (Argasidae) are native to Australia, the ecology of most is poorly known. Argas dewae parasitizes several insectivorous bat species and has been recorded on humans. Therefore, understanding its ecology is crucial for wildlife health management and public health preparedness. To address this knowledge gap, A. dewae populations were monitored from 2 bat hosts (Chalinolobus gouldii and Austronomus australis) using bat boxes at 3 sites in Victoria, Australia, for 28 months (July 2005–December 2007). A phenological profile undertaken for A. dewae revealed that tick load on bat hosts increased throughout winter and peaked in the first month of spring, before collapsing and remaining low throughout the drier late spring and summer periods. There was also further investigation of the relationship between 2 response variables (tick infestation risk and tick load) and a range of explanatory variables (body condition index, sex, age class, bioseason, site, bat density per nest box). In C. gouldii, site was the only significant predictor of A. dewae infestation risk, while load was correlated with several variables including age class, sex, bioseason, roost density and body condition index. This paper also reports the first records of A. dewae from 6 bat species in 3 bat families (Miniopteridae: Miniopterus australis; Molossidae: A. australis; Vespertilionidae: Chalinolobus morio, Myotis Macropus, Vespadelus darlingtonia, Vespadelus regulus) and a second record of A. dewae from a human. The first distribution records are presented for A. dewae in South Australia, the Australian Capital Territory and Queensland.

Cutaneous leishmaniasis (CL) is a vector-borne parasitic disease, routinely diagnosed by direct light microscopy. The sensitivity of this method is dependent on the number of parasites present in the lesion. Immunoexpression of CD1a surface antigen by Leishmania amastigotes and its application as a diagnostic tool has been recently demonstrated in several species including Leishmania major, Leishmania tropica and Leishmania infantum. Leishmania donovani is the only reported species in Sri Lanka primarily causing CL and its CD1a status remains unexplored. We studied CD1a expression by amastigotes of L. donovani in skin biopsies from 116 patients with suspected CL. The biopsy sections were stained with CD1a clones O10 and MTB1 separately. Slit skin smear (SSS) results were considered the gold standard for diagnosis of CL. 103 cases were confirmed through SSS where 73 of them showed positive parasite staining for CD1a clone MTB1 with 70.9% sensitivity. Positivity was seen mostly in parasites closer to the epidermis. CD1a clone O10 failed to detect any amastigotes. Test sensitivity improved to 74.1% when the analysis was applied only to patients with low/no discernible Leishman-Donovan (LD) bodies in histology. Our findings show that CD1a clone MTB1 successfully stains amastigotes of L. donovani species and can be used as a supplementary diagnostic tool in detecting CL, especially when LD bodies are low in number. This method could be validated to detect other forms of leishmaniasis caused by L. donovani in Indian and sub-Saharan regions.

The Amazon basin has the largest number of fish in the world, and among the most common fishes of the Neotropical region, the threespot (Leporinus friderici) is cited, which in relation to its microparasitic fauna, has described only 1 species of the genus Henneguya, Henneguya friderici. The Myxozoa class is considered an obligate parasite, being morphologically characterized by spores formed by valves connected by a suture line. This study describes a new species of Henneguya sp. in the Amazon region for L. friderici. This parasite was found in the host's pyloric caeca and caudal kidney, with mature spores with a total spore length of 38.4 ± 2.5 (35.9–40.9) μm; the spore body 14.4 ± 1.1 (13.3–15.5) μm and 7.3 ± 0.6 (6.7–7.9) μm wide. Regarding its 2 polar capsules, they had a length of 5.1 ± 0.4 (4.7–5.5) μm and a width of 2.0 ± 0.1 (1.9–2.1) μm in the same pear-shaped, and each polar capsule contained 9–11 turns. Morphological and phylogenetic analyses denote that this is a new species of the genus Henneguya.

Oncomelania hupensis (O. hupensis), the sole intermediate host of Schistosoma japonicum, greatly influence the prevalence and distribution of schistosomiasis japonica. The distribution area of O. hupensis has remained extensive for numerous years. This study aimed to establish a valid agent-based model of snail density and further explore the environmental conditions suitable for snail breeding. A marshland with O. hupensis was selected as a study site in Dongting Lake Region, and snail surveys were monthly conducted from 2007 to 2016. Combined with the data from historical literature, an agent-based model of snail density was constructed in NetLogo 6.2.0 and validated with the collected survey data. BehaviorSpace was used to identify the optimal ranges of soil temperature, pH, soil water content, and vegetation coverage for snail growth, development and reproduction. An agent-based model of snail density was constructed and showed a strong agreement with the monthly average snail density from the field surveys. As soil temperature increased, the snail density initially rose before declining, reaching its peak at around 21°C. There were similar variation patterns for other environmental factors. The findings from the model suggested that the optimum ranges of soil temperature, pH, soil water content and vegetation coverage were 19°C to 23 °C, 6.4 to 7.6, 42% to 75%, and 70% to 93%, respectively. A valid agent-based model of snail density was constructed, providing more objective information about the optimum ranges of environmental factors for snail growth, development and reproduction.

Migratory animals likely play an important role in the geographic spread of parasites. In fact, a common assumption is that parasites are potentially transmitted by migratory animals at temporary stopover sites along migratory routes, yet very few studies have assessed whether transmission at stopover sites can or does occur. We investigated the potential for a group of vector-transmitted parasites, the avian haemosporidians, to be transmitted during migratory stopover periods at Rushton Woods Preserve in Pennsylvania, USA. Using an analysis of 1454 sampled avian hosts, we found that while a core group of abundant haemosporidians was shared between local breeding birds and passing migrants, the parasite community of migratory birds at Rushton was distinct from that of local breeding birds and showed similarity to a previously sampled boreal forest haemosporidian community. Haemosporidians that were unique to passing migratory birds were associated with sampling sites in North America with cooler summer temperatures than haemosporidians that are transmitted at Rushton, suggesting that the transmission of these parasites may be restricted to high-latitude regions outside of our temperate stopover site. We also found that the abundance of mosquitoes in our study region is offset from that of migratory bird abundance during avian migratory periods, with the peak period of bird migration occurring during periods of low mosquito activity. Collectively, these findings suggest that although abundant haemosporidians are possibly transmitted between local and passing migratory birds, a combination of biotic and abiotic factors may constrain haemosporidian transmission during avian stopover at our study site.

Ticks are widespread arthropods that transmit microorganisms of veterinary and medical significance to vertebrates, including humans. Rhipicephalus simus, an ixodid tick frequently infesting and feeding on humans, may play a crucial role in transmitting infectious agents across species. Despite the known association of many Rhipicephalus ticks with phleboviruses, information on R. simus is lacking. During a study in a riverine area in Lusaka Zambia, ten R. simus ticks were incidentally collected from the grass and bushes and subjected to metagenomic next generation sequencing (mNGS) in 2 pools of 5. Analysis detected a diverse microbial profile, including bacteria 82% (32/39), fungi 15.4% (6/39), and viruses 2.6% (1/39). Notably, viral sequence LSK-ZM-102022 exhibited similarity to tick phleboviruses, sharing 74.92% nucleotide identity in the RdRp gene and 72% in the NP gene with tick-borne phlebovirus (TBPV) from Greece and Romania, respectively. Its RNA-dependent RNA polymerase (RdRp) encoding region carried conserved RdRp and endonuclease domains characteristic of phenuiviridae viruses. Phylogenetic analysis positioned LSK-ZM-102022 in a distinct but lone lineage within tick phleboviruses basal to known species like brown dog tick phlebovirus and phlebovirus Antigone. Pair-wise genetic distance analysis revealed similar findings. This study emphasizes the urgency of further research on the ecology, transmission dynamics, and pathogenic potential of LSK-ZM-102022 and related TBPVs, crucial for local and global preparedness against emerging tick-borne diseases.

The challenge of American tegumentary leishmaniasis (ATL) continues in Brazil, presenting a persistent public health issue despite initiatives aimed at public outreach, vector control and health education. To gain a deeper understanding of this disease, a study was conducted in an endemic region located in the northern region of the state of Minas Gerais, Brazil. The study monitored 30 resident patients diagnosed with ATL, using serum samples from 6 healthy individuals as controls. The localized cutaneous form of the disease was found to be predominant, with lesions appearing on various parts of the body and the majority of the affected individuals being male. The study found significantly higher levels of IgG anti-α-Gal antibodies in ATL-infected patients compared to healthy individuals. Treatment of 19 patients with meglumine antimoniate resulted in limited improvement in symptoms for most. Nonetheless, the study found that 12 patients who completed treatment with epithelialization of the lesions showed a significant decrease in IgG anti-α-Gal antibodies, indicating potential applications of this antibody in the diagnosis and monitoring of the disease. The study also identified Leishmania species in 7 analysed patients, revealing 6 cases infected by Leishmania braziliensis and 1 by L. infantum, with a significant difference in the anti-α-Gal responses. The findings of the study emphasize the urgent need for the development of human vaccines and innovative treatment strategies adapted to the diversity of Leishmania species causing cutaneous leishmaniasis and individual patient responses to improve the clinical management of ATL in Brazil and similar endemic regions.

Adults of the genus Posthodiplostomum, Dubois, 1936 are parasites of fish-eating birds, mainly of the family Ardeidae, and are globally distributed. The genus currently comprises 35 species, although recent molecular evidence has shown that the diversity of the genus is underestimated since several candidate species have been recognized. In the Neotropical region of Mexico, at least 6 Posthodiplostomum lineages have been detected with metacercaria stages recovered from unrelated fish hosts. Here, we obtained adult specimens of Posthodiplostomum from 6 fish-eating birds representing 2 families (Butorides virescens, Ardea herodias, Nycticorax nycticorax, Tigrisoma mexicanum – Ardeidae, and Rynchops niger and Leucophaeus atricilla – Lariidae) from 4 localities in southern Mexico. Specimens were sequenced for 2 nuclear (28S and ITS1–5.8S–ITS2) and 1 mitochondrial (cox1) molecular marker. Phylogenetic analyses allowed us to link metacercariae and adult specimens and recognized a lineage, which was described morphologically. The new species can be distinguished from its congeners by its prosoma morphology and body size; this is the first described species in the Neotropical region of Mexico. Additionally, new host and locality records for P. macrocotyle and P. pricei are presented, expanding their geographical distribution range in the Americas.