Wood mice (Apodemus sylvaticus) and bank voles (Myodes glareolus) are often employed as natural study models in infectious disease ecology. Yet the identities of some elements of their parasite fauna have been subject to long-standing confusion. One instance of this relates to 2 nominal species of the capillariid nematode genus Aonchotheca: Aonchotheca annulosa (Dujardin, 1845) and A. murissylvatici (Diesing, 1851). Through literature review, analysis of recorded host- and site-specificity and tracing of taxonomic precedence, it is possible to confirm that A. annulosa is a valid species with a spicule c. 1000 microns long, a small intestinal site of infection and a wide host range centred in murine rodents (with A. sylvaticus the most common host). On the other hand, tracing the provenance of A. murissylavtici through to the works of the early naturalists reveals it is best assigned as a nomen nudum (lacking sufficient establishing description) or a junior synonym of A. annulosa and does not have precedence for the other Aonchotheca morphotype commonly found in Eurasian rodents. The first description consonant with this other morphotype, which has a short spicule (200–250 microns in length) and occurs primarily in the stomach of bank voles and other cricetids, was as Capillaria halli by Kalantarian in 1924. We thus recommend the suppression of A. murissyvatici in favour of Aonchotheca halli (Kalantarian, 1924) for this gastric-specialist short-spicule morphotype, particularly as the use of the A. murissylvatici name and its variants has previously been associated with substantial inconsistency and misidentification with A. annulosa.

Soil-transmitted helminth (STH) infections afflict people worldwide, especially in tropical and subtropical regions. Strongyloides stercoralis is distinctive from other STH nematodes by its complex life cycle features of autoinfection, parthenogenesis, and environmental reproduction. This scoping review aims to identify the structures, features, and techniques employed in existing STH models, emphasizing their potential application in describing S. stercoralis infection dynamics. A comprehensive search was conducted in the Medline, Embase, and Scopus databases for studies published until 14 June 2024. A total of 47 studies presenting a new model or novel adaptation of an existing model to human STH infection transmission were identified: only one described S. stercoralis transmission in humans. The identified models were predominantly deterministic and focused on the dynamics of mean worm load within hosts and the infectiousness of the environmental reservoir. One model addressed transmission in multi-host scenarios, as not all STH transmission cycles involve multiple hosts. Models were frequently used to simulate the effectiveness of mass drug administration, including drug efficacy and treatment coverage, while water, sanitation, and hygiene (WASH), health education, and vaccination were less explored. Given the limitation of individual-level data, compartmental models may be a reasonable starting point for S. stercoralis transmission. For a comprehensive understanding, incorporating parasite life cycle features into the model, exploring multi-host dynamics, including a diverse range of host heterogeneities, and assessing the impact of climatic factors like rainfall and land surface temperature on parasite survival in the environment may be beneficial, especially in settings where their importance is notable.

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.

Nosemosis, caused by microsporidian parasites of the genus Nosema, is considered a significant health concern for insect pollinators, including the economically important honeybee (Apis mellifera). Despite its acknowledged importance, the impact of this disease on honeybee survivorship remains unclear. Here, a standard laboratory cage trial was used to compare mortality rates between healthy and Nosema-infected honeybees. Additionally, a systematic review and meta-analysis of existing literature were conducted to explore how nosemosis contributes to increased mortality in honeybees tested under standard conditions. The review and meta-analysis included 50 studies that reported relevant experiments involving healthy and Nosema-infected individuals. Studies lacking survivorship curves or information on potential moderators, such as spore inoculation dose, age of inoculated bees, or factors that may impact energy expenditure, were excluded. Both the experimental results and meta-analysis revealed a consistent, robust effect of infection, indicating a threefold increase in mortality among the infected group of honeybee workers (hazard ratio for infected individuals = 3.16 [1.97–5.07] and 2.99 [2.36–3.79] in the experiment and meta-analysis, respectively). However, the meta-analysis also indicated high heterogeneity in the effect magnitude, which was not explained by our moderators. Furthermore, there was a serious risk of bias within studies and potential publication bias across studies. The findings underscore knowledge gaps in the literature. It is stressed that laboratory cage trials should be viewed as an initial step in evaluating the impact of Nosema on mortality and that complementary field and apiary studies are essential for identifying effective treatments to preserve honeybee populations.

Echinostoma miyagawai is a cosmopolitan parasite within the Echinostomatidae and is a cause of human echinostomiasis. Species within the family have been a challenge to disentangle with E. miyagawai being synonyms of several other Echinostoma species. However, complete mitochondrial genomes have been shown to be vital in distinguishing echinostomatid species, but detailed comparisons of not only gene content but also structural features have been limited. Using long range sequencing techniques, the complete mitochondrial genome of E. miyagawai was sequenced and compared to other members of Echinostomatidae. In total 12 protein coding genes, 2 ribosomal RNA genes and 22 transfer RNA genes were identified, as was an extensive noncoding control region (CR), consisting of 2 types of multiple tandem repeat units. Phylogenetic analyses of complete mitochondrial genomes corresponded to previous studies on single mitochondrial genes and nuclear ribosomal nuclear markers confirmed E. miyagawai to be within in the ‘Echinostoma revolutum’ group. The tandem repeat units found in the CR contained promoter sequences containing domains typical of initiation sites for replication and transcription as well as several palindromic regions which were shared between echinostomatid species. The study illustrates not only the utility complete mitogenomes in disentangling the relationship between these parasite species, but also provides some insight into the potential adaptations and other evolutionary processes that may govern the divergence of mitochondrial genomes for the first time in echinostomatids.

Specimens of Cloacina artemis, C. expansa, C. hera, C. hermes, C. hestia, C. magnipapillata, C. obtusa and C. selene, which occur in both of the closely related species of grey kangaroos, Macropus fuliginosus and M. giganteus, were found to differ genetically based on sequence data derived from the internal transcribed spacers (ITS-1, ITS-2) of ribosomal DNA. The extent of differences varied from a single base pair in C. expansa, to 32 in C. hestia. In the case of C. hera, C. hestia and C. magnipapillata, separate genotypes were found in M. fuliginosus and M. giganteus. With C. artemis, C. expansa, C. obtusa and C. selene, nematode genotypes did not correspond with host distributions. In C. hermes, two genotypes were detected but they were not related phylogenetically. The data provide evidence suggestive of genetic differentiation in most of the nematode species potentially associated with host speciation, but with differing degrees of genetic differentiation and different associations with the two host species possibly related to changes in the geographical distribution of the hosts over time.

The functional diversity structure of a community can be represented as a combination of three additive components (species dominance D, functional redundancy R, and functional diversity Q) (DRQ approach in which different facets of functional differences between species are considered simultaneously). We applied this concept to assemblages of fleas and gamasid mites parasitic on small mammals at continental (across regions of the Palearctic) and regional (across sampling sites in Slovakia) scales and asked: What are the relative effects of host species, biome/habitat type, and geographic locality on the DRQ composition of a parasite assemblage? At the continental scale, regions were partitioned according to predominant biome or geographic position in a continental section. At the regional scale, sampling sites were partitioned according to habitat type or geographic locality. We tested for differences in the functional diversity structure (measured as the DRQ composition) of an ectoparasite assemblage (a) within a host species between biomes/habitat types or continental sections/localities and (b) between host species within a biome/habitat type or a continental section/locality. At both scales, the functional diversity structure of both flea and mite assemblages differed mainly between host species within a biome/habitat or geographic regions/locations, whereas differences in the DRQ composition between biomes/habitats or geographic regions/locations were only detected in a few host species. We compare our results with the results of earlier studies and conclude that the DRQ approach has an advantage over a single diversity metric and allows a better understanding of spatial variation in different facets of ectoparasite diversity.

This study presents the first detection of Taenia omissa metacestodes in guanaco (Lama guanicoe) within the Chilean Patagonia, marking the southernmost record of natural infection in an intermediate host on the continent. Taenia omissa was found in the continental part of the Magallanes region where the top predators are pumas (Puma concolor). Conversely, all metacestodes found in guanacos collected from Tierra del Fuego Island, where no pumas exist, were identified solely as Echinococcus granulosus sensu stricto. Additionally, this research highlights a tissue preference of T. omissa for liver, contrasting with E. granulosus, which predominantly affects the lungs in guanacos. We also report the infection of T. pisiformis in 1 guanaco. Our findings emphasize the need for accurate identification of metacestodes during meat inspection in an area where T. omissa and E. granulosus overlap. This research also contributes to increase the knowledge of parasite–host dynamics in wildlife and underscores the importance of considering broader spectrum intermediate hosts in the epidemiology of parasitic infections.

Austropotamobius pallipes complex is an endangered freshwater crayfish species in Europe and the assessment of the health status of its wild populations is essential for conservation purposes. The two microsporidia Astathelohania contejeani and Nosema austropotamobii have been reported to cause in A. pallipes complex a chronic parasitic infection, known as ‘porcelain disease’, which reduces population fitness and leads the host to death. Due to the similar macroscopic signs produced, molecular biology analyses are required to unambiguously distinguish between these microsporidia. Focusing on A. pallipes complex populations located in Northern and Central Italy, the present study provides an evaluation of prevalence and distribution of A. contejeani and N. austropotamobii, and investigates the variables affecting the probability of detecting infected specimens during a survey (e.g. sex, crayfish density, longitude). Microsporidia were identified in 12 populations among the 42 monitored from 2011 to 2017, with an average prevalence of 3.12% for A. contejeani and 3.60% for N. austropotamobii, the latter being reported in a wider area than previously documented (from Lombardy to Liguria Regions). Notably, crayfish co-infected by both microsporidia were also detected in 4 populations. Moreover, it was observed that the probability of detecting a crayfish with a microsporidian infection significantly increased eastwards in the studied area, especially for N. austropotamobii. Our distribution map for microsporidiosis, combined with molecular screening, will be useful for planning breeding and translocation efforts for A. pallipes complex populations.

Parasite species interactions, host biology traits, and external environmental factors can drive co-occurrence patterns between parasite species. We investigated co-occurrence patterns between three ectoparasite species (mite (Neotrombicula harperi), and fleas (Orchopeas caedens and Ceratophyllus vison)) of North American red squirrels (Tamiasciurus hudsonicus). We evaluated (1) whether ectoparasites of red squirrels exhibit non-random co-occurrence patterns, and (2) the contribution of host and external environmental factors to parasite co-occurrence. Bayesian ordination and regression analysis (boral) revealed random associations between parasite species pairs when accounting for host and external environmental factors. However, the mite N. harperi exhibited a negative association with the flea O. caedens and positive association with the flea C. vison linked to temporal patterns of occurrence. Our data suggests that parasites of the investigated population of red squirrels tend to form associations based on temporal trends in infestation rather than species interactions. Further experimentation should investigate the role of additional factors on parasite co-occurrence patterns, such as temperature, precipitation, and humidity.