The dominant helminths infecting spiny mice (Acomys dimidiatus) in the montane wadis of the Sinai Peninsula of Egypt are spirurid nematodes, notably Protospirura muricola and Mastophorus muris. Both are relatively large robust stomach worms that accumulate in hosts resulting in high worm burdens. To ascertain whether the presence of spirurid worms or their burdens alters the host's likelihood of infection with other helminth species, we analysed a database containing quantitative data on helminth parasites of these mice (n = 431). This comprised of worm burdens recorded during 4 surveys, conducted at 4-year intervals, in 4 wadis, during late summer of each year. The presence of spirurid worms did not significantly alter species richness with other helminth species nor the likelihood of mice carrying other nematode species. However, there was a significant association, particularly of P. muricola, with the presence of intestinal stages of cestodes, and with the acanthocephalan Moniliformis acomysi. After controlling for intrinsic and extrinsic factors, mice harbouring spirurid worms had greater worm burdens of other helminths compared with mice without spirurids. Moreover, spirurid worm burdens showed a significant positive covariation with similarly adjusted species richness of other helminths, non-spirurid helminths, non-spirurid nematodes, oxyuroid nematodes and intestinal stage cestode worm burdens. We interpret these results as an indication that the key driver for co-occurrence of spirurids with other helminths is likely to be transmission via common arthropod hosts (for cestodes and acanthocephalans), but also that mice carrying the heavier spirurid worm burdens become more susceptible to directly transmitted nematodes such as the Oxyuroidea.

Stranded seals are often infected with a broad range of parasites, although whether they are the cause of significant morbidity or an incidental finding is usually unclear. In this study we used stable isotope ratio analysis, a method frequently used to investigate food webs, to explore the extent to which common seal parasites feed directly on host tissue and fluids or absorb host-derived metabolites, which in turn may give an indication of their potential impact on the host's health. The trophic discrimination factor Δ15N for the nasal mite, Halarachne halichoeri, was mostly positive, ranging between −0.015 and 3.2‰ (n = 6), while for the Acanthocephalan worm, Corynosoma strumosum and the anisakid nematode, Pseudoterranova decipiens, Δ15N ranged between −4.2 and −2.0‰ (n = 7), and between −6.7 and −0.8‰ (n = 5) respectively. In the case of the lungworm, Otostrongylus circumlitus, Δ15N measured between −5.6 and 0‰ for worms collected in the stomach (n = 5), between −1.1 and 0.2‰ for worms collected from the heart (n = 3), between −0.7 and 1.9‰ for worms situated in the lungs (n = 4). Based on Δ15N, parasites could be clearly divided into those that were on a higher trophic level than their host suggesting a predator–prey-like relationship, and those that were not. It is hypothesized that Δ15N may be indicative of the clinical significance of parasite–host associations.

The genus Tanqua Blanchard, 1904, infests reptiles, particularly those inhabiting aquatic environments. This study examined a population of rainbow water snakes, Enhydris enhydris (Schneider, 1799), collected from southern Thailand. Adult nematodes consistent with Tanqua were found in the stomach. Various morphometric, meristic and qualitative morphological variables, including size, ratios, distances, cephalic appearance, the number of caudal papillae and other features, serve to distinguish the specimens from other species within the genus. In particular, Tanqua anomala and Tanqua diadema, which closely resemble our Tanqua specimens, can be differentiated by key diagnostic characteristics such as a retractable head, the distance from the anterior end to the cervical sac, the relative positions of caudal papillae and excretory pore, and the length of the uterus. Molecular analysis (COI and 18s rRNA genes) confirmed its status as a species of Tanqua, genetically distinct from Tanqua tiara, and matching the genetic sequence found in larvae of Tanqua sp. from a snakehead fish species from Bangladesh. Tanqua siamensis sp. nov. is described, supported by morphological traits, microscopic illustrations and genetic information. This study reports the first evidence of a caudal papillary pair in females. This species causes significant lesions on the stomach wall of the snake host, raising possible issues for snakes held in captivity regarding food hygiene and parasite protection.

Visceral leishmaniasis (VL) is a severe infectious disease caused by protozoan parasites of the Leishmania donovani complex. Blood cytokine concentrations in VL patients can inform us about underlying immunopathogenesis and may serve as a biomarker for treatment effectiveness. However, cytokine levels have not yet been studied in VL patients from Kenya, where case load is high. This study measured the serum cytokine profile, blood parasite load and clinical and haematological features of VL patients from West Pokot County, Kenya, over the course of treatment with sodium stibogluconate and paromomycin (SSG-PM). VL patients recruited at the hospital presented with splenomegaly and weight loss, and frequently had pancytopenia and anaemia. Median Leishmania parasite load in blood, determined with real-time polymerase chain reaction, was 2.6 × 104 parasite equivalents mL−1. Compared to endemic healthy controls, serum interferon gamma (IFN-γ), interleukin 5 (IL-5), IL-6, IL-10, IL-12p70, IL-17A and IL-27 were significantly elevated in untreated VL patients. Severe VL was associated with higher IL-10 and lower IFN-γ levels. After 17 daily injections with SSG-PM, disease symptoms disappeared, leukocyte and thrombocyte counts significantly increased, and blood parasite load decreased to undetectable levels in all VL patients. There was a significant decrease in IL-10 and IL-6, whereas IL-17A levels increased; the remaining cytokines showed no significant concentration change during treatment. In conclusion, the results suggest that SSG-PM treatment of VL patients from West Pokot was effective. Moreover, both inflammatory and regulatory immune responses appeared to decrease during treatment, although the increase in IL-17A could reflect a partial continuation of immune activation.

During investigation of common linnet (Linaria cannabina) blood using the buffy coat method one bird with microfilariae in the blood was found. The morphometric description of adult worms corresponded to the Chandlerella sinensis. This species was found for the first time in common linnets. DNA sequences of cox1 and 28S gene fragments of adult worm recovered during necropsy was identical to that from the microfilariae in the bird blood. Phylogenetic analysis of the cox1 gene fragment clustered this parasite with Chandlerella quiscali. Histological examination revealed the presence of microfilariae in the lumen of small capillaries and other blood vessels in different organs, but no inflammations were notice. The greatest number of microfilariae was in the lungs. Even if there was no inflammation, but vessels associated with the lungs were markedly distended with blood, parabronchial walls were thickened and, in some cases, almost completely obstructing the lumen. The large number of microfilariae in lungs indicates possible disturbance of gas exchange in the lungs adversely affected the ability of the bird to exercise and made breathing difficult at rest. The investigation of circadian rhythm of the microfilariae showed that C. sinensis microfilariae in blood of common linnet were more numerous at night and morning and less numerous at midday. The survival rate of mosquitoes infected with C. sinensis microfilariae was significantly lower than that of uninfected mosquitoes.

Maternal bacterial and viral infections that induce neuroinflammation in the developing brain are associated with impaired cognitive function and increased anxiety in the offspring. In contrast, maternal infection with the immunoregulatory murine gastrointestinal (GI) nematode, Heligmosomoides bakeri, appears to benefit neurodevelopment as juvenile 2- and 3-week-old male and female offspring had enhanced spatial memory, which may be due to a Th2/Treg biased neuroimmune environment. Here, the impact of maternal H. bakeri infection during pregnancy and lactation on the spatial and anxiety-like behaviours of adult, 3-month-old uninfected male and female offspring was explored for the first time. It was observed that adult female offspring of H. bakeri-infected dams had enhanced spatial reference memory and reduced anxiety-like behaviour compared to females of uninfected dams. These effects were not observed in adult male offspring. Thus, the positive influence of a maternal GI nematode infection on spatial memory of juvenile offspring persists in adult female offspring.

Parasite community structure is governed by functional traits of hosts and parasites. Notably, parasite populations and communities respond to host social and spatial behaviour. Many studies demonstrating these effects dealt with small-bodied host species, while the influence of host social patterns on parasite communities in large hosts remains understudied. In an earlier study on nyalas (Tragelaphus angasii), host age was more important than sex in structuring helminth communities and networks, but the influence of both was mediated by local environmental conditions, creating different locality patterns. Common reedbuck (Redunca arundinum) differ from nyalas in spatial and social behaviour. Based on helminth and ectoparasite data from 56 reedbuck examined at 2 localities in KwaZulu-Natal Province, we asked which patterns are similar and which differ between the 2 host species. Similar to nyalas, reedbuck age was more important than sex in structuring communities and networks. However, local environmental conditions exerted the strongest influence on transmission patterns, especially in ectoparasites. Complex interactions between reedbuck traits, parasite traits and local environmental conditions modulated the risk of infection differently at the 2 sites, confirming our earlier findings in nyalas that pooling data from different locations may obscure location-specific parasite community patterns. Similarities between patterns in reedbuck and nyalas, despite their behavioural differences, suggest some common patterns in parasite community ecology that, in turn, are determined mostly by parasite traits and population dynamics.

Few studies have examined the genetic population structure of vector-borne microparasites in wildlife, making it unclear how much these systems can reveal about the movement of their associated hosts. This study examined the complex host–vector–microbe interactions in a system of bats, wingless ectoparasitic bat flies (Nycteribiidae), vector-borne microparasitic bacteria (Bartonella) and bacterial endosymbionts of flies (Enterobacterales) across an island chain in the Gulf of Guinea, West Africa. Limited population structure was found in bat flies and Enterobacterales symbionts compared to that of their hosts. Significant isolation by distance was observed in the dissimilarity of Bartonella communities detected in flies from sampled populations of Eidolon helvum bats. These patterns indicate that, while genetic dispersal of bats between islands is limited, some non-reproductive movements may lead to the dispersal of ectoparasites and associated microbes. This study deepens our knowledge of the phylogeography of African fruit bats, their ectoparasites and associated bacteria. The results presented could inform models of pathogen transmission in these bat populations and increase our theoretical understanding of community ecology in host–microbe systems.

As a member of the Scathophagidae family, Scathophaga stercoraria (S. stercoraria) is widely distributed globally and is closely associated with animal feces. It is also a species of great interest to many scientific studies. However, its phylogenetic relationships are poorly understood. In this study, S. stercoraria was found in plateau pikas for the first time. The potential cause of its presence in the plateau pikas was discussed and it was speculated that the presence of S. stercoraria was related to the yak feces. In addition, 2 nuclear genes (18SrDNA and 28SrDNA), 1 mitochondrial gene (COI), and the complete mitochondrial genome of S. stercoraria were sequenced. Phylogenetic trees constructed based on 13 Protein coding genes (13PCGs), 18S and 28S rDNA showed that S. stercoraria is closely related to the Calliphoridae family; phylogenetic results based on COI suggest that within the family Scathophagidae, S. stercoraria is more closely related to the genus Leptopa, Micropselapha, Parallelomma and Americina. Divergence times estimated using the COI gene suggest that the divergence formation of the genus Scathophaga is closely related to changes in biogeographic scenarios and potentially driven by a combination of uplift of the Qinghai-Tibetan Plateau (QTP) and dramatic climate changes. These results provide valuable information for further studies on the phylogeny and differentiation of the Scathophaga genus in the future.

Cylicospirura Vevers, 1922 is a genus of gastrointestinal spirurid nematodes parasitizing mainly felid but also canid, hyaenid and dasyurid hosts. Presently, 11 species are recognized worldwide, of which 4, Cylicospirura subaequalis, Cylicospirura felinea, Cylicospirura crocutae and Cylicospirura pardalis, have been recorded from African carnivores. In the present study, we describe Cylicospirura phiri n. sp. from hyaenas, namely Crocuta crocuta (type host) in Zimbabwe and Hyaena hyaena in Cameroon. The new species is the second species in the genus with bicuspid teeth. Furthermore, it can be distinguished from its congeners by a combination of characters, such as the absence of accessory teeth, the length and shape of the muscular oesophagus, position of the nerve ring, deirids and excretory pore in relation to the muscular oesophagus, the position of the vulva, spicule length and the shape of the female tail. Additionally, based on new material, detailed morphological descriptions are provided for C. crocutae and C. pardalis whose original descriptions were based on fragmented material. The material from Felis lybica, currently deposited as C. subaequalis, is described as C. felinea. First-time scanning electron micrographs are presented for the 4 species confirmed in African carnivores.

Members of the genus Scaphanocephalus mature in accipitrids, particularly osprey, Pandion haliaetus, with metacercaria causing Black Spot Syndrome in reef fishes. In most of the world, only the type species, Scaphanocephalus expansus (Creplin, 1842) has been reported. Recent molecular studies in the Western Atlantic, Mediterranean and Persian Gulf reveal multiple species of Scaphanocephalus, but have relied on 28S rDNA, mainly from metacercariae, which limits both morphological identification and resolution of closely related species. Here we combine nuclear rDNA with mitochondrial sequences from adult worms collected in osprey across North America and the Caribbean to describe species and elucidate life cycles in Scaphanocephalus. A new species described herein can be distinguished from S. expansus based on overall body shape and size. Phylogenetic analysis of the whole mitochondrial genome of Scaphanocephalus indicates a close relationship with Cryptocotyle. We conclude that at least 3 species of Scaphanocephalus are present in the Americas and 2 others are in the Old World. Specimens in the Americas have similar or identical 28S to those in the Mediterranean and Persian Gulf, but amphi-Atlantic species are unlikely in light of divergence in cytochrome c oxidase I and the lack of amphi-Atlantic avian and fish hosts. Our results provide insight into the geographic distribution and taxonomy of a little-studied trematode recently linked to an emerging pathology in ecologically important reef fishes.

With the increasing affordability of next-generation sequencing technologies, genotype-by-sequencing has become a cost-effective tool for ecologists and conservation biologists to describe a species' evolutionary history. For host–parasite interactions, genotype-by-sequencing can allow the simultaneous examination of host and parasite genomes and can yield insight into co-evolutionary processes. The eastern oyster, Crassostrea virginica, is among the most important aquacultured species in the United States. Natural and farmed oyster populations can be heavily impacted by ‘dermo’ disease caused by an alveolate protist, Perkinsus marinus. Here, we used restricted site-associated DNA sequencing (RADseq) to simultaneously examine spatial population genetic structure of host and parasite. We analysed 393 single-nucleotide polymorphisms (SNPs) for P. marinus and 52,100 SNPs for C. virginica from 36 individual oysters from the Gulf of Mexico (GOM) and mid-Atlantic coastline. All analyses revealed statistically significant genetic differentiation between the GOM and mid-Atlantic coast populations for both C. virginica and P. marinus, and genetic divergence between Chesapeake Bay and the outer coast of Virginia for C. virginica, but not for P. marinus. A co-phylogenetic analysis confirmed significant coupled evolutionary change between host and parasite across large spatial scales. The strong genetic divergence between marine basins raises the possibility that oysters from either basin would not be well adapted to parasite genotypes and phenotypes from the other, which would argue for caution with regard to both oyster and parasite transfers between the Atlantic and GOM regions. More broadly, our results demonstrate the potential of RADseq to describe spatial patterns of genetic divergence consistent with coupled evolution.

Ixodid ticks are obligate blood-feeding arthropods and important vectors of pathogens. In Mallorca, almost no data on the tick fauna are available. Herein, we investigated ticks and tick-borne pathogens in ticks collected from dogs, a cat and humans in Mallorca as result of a citizen science project. A total of 91 ticks were received from German tourists and residents in Mallorca. Ticks were collected from March to October 2023 from dogs, cat and humans, morphologically and genetically identified and tested for pathogens by PCRs. Six tick species could be identified: Ixodes ricinus (n = 2), Ixodes ventalloi (n = 1), Hyalomma lusitanicum (n = 7), Hyalomma marginatum (n = 1), Rhipicephalus sanguineus s.l. (n = 71) and Rhipicephalus pusillus (n = 9). Rhipicephalus sanguineus s.l. adults were collected from dogs and four females from a cat and the 16S rDNA sequences identified it as Rh. sanguineus s.s. Hyalomma lusitanicum was collected from 1 human, 1 dog and 5 specimens were collected from the ground in the community of Santanyi, together with one H. marginatum male. This is the first report of Hyalomma marginatum in Mallorca. Both I. ricinus were collected from humans and I. ventalloi female was collected from a dog. All ticks tested negative for Anaplasma phagocytophilum, Coxiella spp., Francisella spp., and piroplasms. In 32/71 (45%) specimens of Rh. sanguineus s.s., Rickettsia spp. could be detected and in 18/32 (56.2%) sequenced tick DNAs R. massiliae was identified. Ixodes ventalloi female and both I. ricinus tested positive in the screening PCR, but the sequencing for the identification of the Rickettsia sp. failed.

Small nucleolar RNAs (snoRNAs) are short non-coding RNAs that are abundant in the nucleoli of eukaryotic cells and play a crucial role in various aspects of ribosomal RNA (rRNA) maturation, including modifications such as 2′-O-methylation or pseudouridylation. On the other hand, Giardia duodenalis is a microaerophilic, flagellated, binucleate protozoan responsible for causing giardiasis. Although numerous snoRNAs have been detected in Giardia, their investigation remains limited. Nevertheless, they have been found to play a crucial role in the rRNA precursor processing pathway and influence other cellular functions. In addition, it has been proposed that some microRNAs are generated from these snoRNAs through excision by the Giardia endoribonuclease Dicer. These microRNAs are believed to contribute to the regulation of antigenic variation, which allows the parasite to evade the host immune response. Specifically, they play a role in modulating variant-specific surface proteins (VSPs) and other cysteine-rich surface antigens (CSAs). The main objective of this study was to bring together the available data on snoRNAs in Giardia, uncovering their functions in various processes and their importance on a global scale. In addition, the research delved into potential microRNAs speculated to originate from snoRNAs, exploring their impact on cellular processes.

Manipulation of host behaviour by parasites to enhance transmission to the next host is a fascinating phenomenon that has interested scientists since the 1970s. It has been proposed that infection with the cestode Echinococcus multilocularis produces an impairment of the antipredatory behaviour in the rodent intermediate host common vole, Microtus arvalis, which may facilitate transmission of the tapeworm to the canid final host. In this study, we observed the behaviour of infected common voles at 12 weeks post-infection, when protoscoleces production and maturation commonly occurs, in order to assess behavioural changes compared to uninfected controls, that might ease predation in the wild. Infected and uninfected voles were monitored for 24 h to observe their spontaneous activity. In addition, the next day, both infected and uninfected voles were subjected to 4 different behavioural tests: open field test, barrier test, platform test and air-puff test in a running wheel. No significant difference between uninfected and infected voles emerged during the behavioural tests. However, observation of spontaneous activity revealed that infected voles increased their feeding frequency and spent significantly more time above bedding even when not eating, compared to the uninfected controls. In the wild, these behavioural changes increase the animals exposure to predators, raising their chance of becoming prey. These findings are the first direct evidence consistent with behavioural manipulation by E. multilocularis on common voles.

Philometroides Yamaguti, 1935 is a genus of dracunculoid nematodes of the family Philometridae Baylis & Daubney, 1926 comprising tissue-infecting species worldwide. In the present study, a new species of Philometroides is described from the Tyrrhenian Sea (central-western Mediterranean Sea) using integrative approaches such as light and scanning microscopy, histopathology and 18S rRNA sequencing. Philometroides giginosantoroi n. sp. found in the skeletal muscles of the Mediterranean moray Muraena helena can be distinguished from its congeners by a combination of morphological traits and in particular by having the oral aperture with 3 large sclerotized triangular oesophageal teeth. The molecular analyses and phylogenetic reconstructions support its status as a new taxon and placed it within a clade of tissue-infecting species, although also confirmed mismatches in the generic assignment of several species. Philometroides giginosantoroi n. sp. is the second species of the genus found in the Mediterranean Sea and in general in the European marine waters and the third species of the family known to infect the family Muraenidae.

Sculpins (coastrange and slimy) and sticklebacks (ninespine and threespine) are widely distributed fishes cohabiting 2 south-central Alaskan lakes (Aleknagik and Iliamna), and all these species are parasitized by cryptic diphyllobothriidean cestodes in the genus Schistocephalus. The goal of this investigation was to test for host-specific parasitic relationships between sculpins and sticklebacks based upon morphological traits (segment counts) and sequence variation across the NADH1 gene. A total of 446 plerocercoids was examined. Large, significant differences in mean segment counts were found between cestodes in sculpin (mean = 112; standard deviation [s.d.] = 15) and stickleback (mean = 86; s.d. = 9) hosts within and between lakes. Nucleotide sequence divergence between parasites from sculpin and stickleback hosts was 20.5%, and Bayesian phylogenetic analysis recovered 2 well-supported clades of cestodes reflecting intermediate host family (i.e. sculpin, Cottidae vs stickleback, Gasterosteidae). Our findings point to the presence of a distinct lineage of cryptic Schistocephalus in sculpins from Aleknagik and Iliamna lakes that warrants further investigation to determine appropriate evolutionary and taxonomic recognition.