A total of 32 taxa of helminths were recovered from 52 individuals corresponding to 17 species of didelphiomorph marsupials collected across Bolivia. From these, 20 taxa are registered for the first time in this landlocked South American country, including the cestode Mathevotaenia bivittata, and the nematodes Moennigia sp., Travassostrongylus callis, Viannaia didelphis, V. hamata, V. metachirops, V. minispicula, V. philanderi, V. simplicispicula, V. skrjabini, V. viannai, Cruzia tentaculata, Monodelphoxyuris dollmeiri, Neohilgertia venusti, Pterygodermatites elegans, Pterygodermatites jeagerskioldi, Spirura guianensis, Gongylonemoides marsupialis, Turgida turgida and Trichuris reesali. We report for the first time parasites for Marmosops bishopi, Monodelphis emiliae, Monodeplhis glirina, Monodelphis sanctarosae, Monodelphis peruviana and Thylamys sponsorius and document 38 new records of parasites infecting marsupials. Twenty-six taxa of helminths infect 2 or more species of didelphiomorph marsupials, with the exception of Travassostrongylus callis, Viannaia didelphis, V. hamata, V. minispicula and V. hamate, which infected individuals of a single species.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.