Microbial artists: the role of parasite microbiomes in explaining colour polymorphism among amphipods and potential link to host manipulation.

Parasite infections are increasingly reported to change the microbiome of the parasitized hosts, while parasites bring their own microbes to what can be a multi-dimensional interaction. For instance, a recent hypothesis suggests that the microbial communities harboured by parasites may play a role in the well-documented ability of many parasites to manipulate host phenotype, and explain why the degree to which host phenotype is altered varies among conspecific parasites. Here, we explored whether the microbiomes of both hosts and parasites are associated with variation in host manipulation by parasites. Using colour quantification methods applied to digital images, we investigated colour variation among uninfected Transorchestia serrulata amphipods, as well as amphipods infected with Plagiorhynchus allisonae acanthocephalans and with a dilepidid cestode. We then characterized the bacteriota of amphipod hosts and of their parasites, looking for correlations between host phenotype and the bacterial taxa associated with hosts and parasites. We found large variation in amphipod colours, and weak support for a direct impact of parasites on the colour of their hosts. Conversely, and most interestingly, the parasite's bacteriota was more strongly correlated with colour variation among their amphipod hosts, with potential impact of amphipod-associated bacteria as well. Some bacterial taxa found associated with amphipods and parasites may have the ability to synthesize pigments, and we propose they may interact with colour determination in the amphipods. This study provides correlational support for an association between the parasite's microbiome and the evolution of host manipulation by parasites and host-parasite interactions more generally.

First report of apparent praziquantel resistance in Dipylidium caninum in Europe.

Dipylidium caninum is a common tapeworm of dogs. Two cases of praziquantel resistance have been described in D. caninum in the United States. No further reports have been published to the authors' knowledge. Here, the case of a dog imported to Switzerland from Spain with a history of chronic excretion of tapeworm proglottids and unresponsiveness to praziquantel treatments is reported. Clinical signs were mild (restlessness, tenesmus, anal pruritus, squashy feces) and flea infestation could be ruled out. Infection with D. caninum was confirmed through morphological and genetic parasite identification. Different subsequently applied anthelmintic compounds and protocols, including epsiprantel, did not confer the desired effects. Proglottid shedding only stopped after oral mebendazole administration of 86.2 mg kg−1 body weight for 5 consecutive days. Clinical signs resolved and the dog remained coproscopically negative during a follow-up period of 10 months after the last treatment. This case represents the first reported apparent praziquantel and epsiprantel resistance in D. caninum in Europe. Treatment was extremely challenging especially due to the limited availability of efficacious alternative compounds.

Efficacy of Lactobacillus taiwanensis S29 and Lactiplantibacillus plantarum S27 against tapeworm infection in Swiss Albino rats.

Hymenolepis diminuta a zoonotic tapeworm infection in human remains an important cestode model for anthelmintic study as it display common clinical symptoms like other adult human tapeworms during heavy infestation. The use of Lactobacillus as a probiotic is an alternative to drugs which have increased in research and usage considerably during the last decade. The present study aims to determine the anthelmintic efficacy of two probiotics, L. taiwanensis strain S29 and L. plantarum strain S27 against H. diminuta in infected rat. Four groups of animals, each with six numbers were randomly chosen as the negative control (Group I), positive control (infected) (Group II) and the infected treated with two probiotics Group III and Group IV respectively. Another four groups (Group V-VIII) were selected and further subdivided into four sub-groups to investigate the development of larvae to adult during probiotics treatment. Worm burden, egg per gram were determined after treatment with these two probiotics. Furthermore, hematological assays and levels of biochemical markers were estimated, tissue damage was assayed through histological study and intestinal mitochondria detection was done. Worm sustainability reduced about 70-90% and EPG count decreased by 81-94% in probiotics treated groups. A significant level of unsuccessful establishment of larvae was observed in the developmental phase. Improvement in hematological parameter along with some biochemical parameters in the host were significantly observed after treatment with probiotics. The architecture damaged caused in the intestine and mitochondria density due to parasite infection improved significantly as that of control after probiotics treatment.

Antimicrobial and anthelmintic effects of copper nanoparticles against Koi carp parasites and their toxicity.

This study investigated the in vitro antimicrobial and anthelmintic effect of copper nanoparticles (CuNPs) against the bacterium Aeromonas hydrophila, the monogeneans Dactylogyrus minutus, Dactylogyrus extensus, Gyrodactylus cyprini, and the cestode Schyzocotyle acheilognathi, as well as their toxicity to Cyprinus carpio Koi. In the antimicrobial in vitro test, the inhibition zone method and minimum inhibitory concentration (MIC) were performed. In order to determine the time and efficacy of monogenean parasite mortality, the parasites were exposed to CuNP concentrations of 20, 50, 100, 150, 200, and 300 mg L-1, and a control group with tank water and one with copper sulphate pentahydrate (CuSO4.5H2O) at a concentration of 0.3 mg L-1, performed in triplicate. The parasites were observed every 10 min for 300 min, and mortality was recorded. For the cestodes, parasites were immersed in CuNP concentrations of 50, 100, 150, and 300 mg L-1. At the end of the in vitro tests, the anthelmintic efficacy of each treatment was calculated. To assess the tolerance and toxicity in fish, they were exposed to CuNP concentrations of 0.6, 1.25, 2.5, 5, 10, 20, and 50 mg L-1 for 12 h. The MIC demonstrated that CuNPs effectively inhibited the growth of A. hydrophila up to a dilution of 12,500 mg L-1 and showed an inhibition zone of 14.0 ± 1.6 mm for CuNPs. The results of anthelmintic activity showed a dose-dependent effect of concentration for both groups of parasites, with the most effective concentration being 300 mg L-1 in 120 min. In the toxicity test, the carps showed tolerance to lower concentrations. The study indicated that CuNPs were effective against the studied pathogens. However, it proved to be toxic to fish at high concentrations. The use of low concentrations is recommended still requires further investigation.

Visceral cysticercosis in a Kunekune sow: description and molecular identification of Taenia hydatigena.

A 2-year-old Kunekune sow was submitted for necropsy following death after peritonitis and sepsis. In addition to peritonitis, numerous fluid-filled cysts were identified in the mesentery and hepatic parenchyma, which contained an approximately 1 cm metacestode (cysticercosis). Subsequent molecular characterization confirmed the presence of Taenia hydatigena, a non-zoonotic cestode species. To our knowledge, visceral cysticercosis caused by T. hydatigena has not been previously documented in Kunekune pigs. Taenia solium is a differential diagnosis of public health importance in cases of cysticercosis. Although Taenia solium is not commonly reported nor endemic in the United States, its zoonotic potential warrants consideration in the initial diagnostic assessment. Clinicians should be aware of the presence of T. hydatigena in its definitive and intermediate hosts.

Molecular characterization of Bertiella studeri infecting a primate in South India.

Bertiella spp. is a mite-borne cestode parasite that inhabits the small intestine of wide range of mammals, including non-human primates. In the present study, the morphological and molecular analysis of Bertiella studeri recovered from the small intestine of a bonnet macaque (Macaca radiata) from Wayanad, Kerala (South India) was performed. Acetic alum carmine staining identified the cestode morphologically based on the characters like broader proglottids, which contain irregularly alternating genital pores, single set of reproductive organs, 280 testes and a tubular transverse uterus. Molecular characterization was done using 18SrRNA, ITS1-5.8S and COX1 genes. Phylogenetic trees were constructed using MEGA X based on the Maximum Likelihood (ML) method (Hasegawa-Kishino-Yano (HKY) model). Cytochrome oxidase I gene could detect the existence of genetic variation in the parasite from two different hosts viz., monkey (Kerala, Argentina, and Kenya) and human (Sri Lanka). A minimum spanning network of haplotypes was generated by the haplotype networking with the above sequences using the popARTv1.7. Haplotype analysis based on COX1 revealed that the parasite haplotype was different in each country with highest population frequency in Sri Lanka.

Long live the host! Proteomic analysis reveals possible strategies for parasitic manipulation of its social host.

Parasites with complex life cycles often manipulate the phenotype of their intermediate hosts to increase the probability of transmission to their definitive hosts. Infection with Anomotaenia brevis, a cestode that uses Temnothorax nylanderi ants as intermediate hosts, leads to a multiple-fold extension of host lifespan and to changes in behaviour, morphology and colouration. The mechanisms behind these changes are unknown, as is whether the increased longevity is achieved through parasite manipulation. Here, we demonstrate that the parasite releases proteins into its host with functions that might explain the observed changes. These parasitic proteins make up a substantial portion of the proteome of the hosts' haemolymph, and thioredoxin peroxidase and superoxide dismutase, two antioxidants, exhibited the highest abundances among them. The largest part of the secreted proteins could not be annotated, indicating they are either novel or severely altered during recent coevolution to function in host manipulation. We also detected shifts in the hosts' proteome with infection, in particular an overabundance of vitellogenin-like A in infected ants, a protein that regulates division of labour in Temnothorax ants, which could explain the observed behavioural changes. Our results thus suggest two different strategies that might be employed by this parasite to manipulate its host: secreting proteins with immediate influence on the host's phenotype and altering the host's translational activity. Our findings highlight the intricate molecular interplay required to influence the phenotype of a host and point to potential signalling pathways and genes involved in parasite-host communication.

The influence of parasite load on transcriptional activity and morphology of a cestode and its ant intermediate host.

Parasites with complex life cycles are known to induce phenotypic changes in their intermediate hosts to increase transmission to the final host. The magnitude of these changes could increase with the number of parasites, which would be beneficial to co-infecting parasites. Yet, adverse effects of high parasite load (i.e. many parasites in a single host) might stress both hosts and parasites (e.g. through an increased immune response). We investigated the consequences of parasite load on the transcriptional activity and morphology of the cestode Anomotaenia brevis and its intermediate host, the ant Temnothorax nylanderi. We demonstrated that many differentially expressed host genes shifted with parasite load, and their functions indicate a stronger immune response and fight against oxidative stress in heavily infected hosts. The expression of other host genes responded to infection in an all-or-nothing manner, as did the morphology of the host workers. However, the cestodes became smaller when they competed with other parasites for resources from a single host. Their expression profile further indicated shifts in host immune avoidance, starvation resistance and vesicle-mediated transport. In summary, our study reveals clear consequences of parasite load and highlights specific processes and traits affected by this.

Current status of cystic echinococcosis control in the Falkland Islands: has elimination been achieved?

Attempts to control cystic echinococcosis (CE) caused by Echinococcus granulosus in the Falkland Islands have been ongoing for over 50 years. No human cases have been recorded since the 1980s but there is a need to establish if the parasite has been completely eliminated from domestic animals. A study was carried out in 2018/2019 to identify dogs infected with E. granulosus using copro-antigen and copro-polymerase chain reaction (PCR) analysis. In addition, annual slaughter data were analysed to establish infection levels of E. granulosus and 2 other taeniid parasites. Results showed that 4 out of 589 dogs (0.7%) tested positive by copro-antigen analysis. Results from similar surveys carried out in 2010, 2012 and 2014 showed 17 (3%), 0 and 6 (1%) copro-antigen-positive dogs, respectively, with 8 dogs being confirmed by PCR in 2010. Annual abattoir data showed that from 2006 to 2020, 36 sheep were identified with E. granulosus (mean 0.0055%), 14 186 sheep with Taenia hydatigena (mean 2.2%) and 465 with Taenia ovis (mean 0.072%). Prevalences of T. hydatigena and T. ovis showed spontaneous rises in certain years where the infections could also be detected in lambs indicating that viable taeniid eggs were present. Observations of farm management procedures indicated that there were occasions when dogs could get access to infective taeniid material. In conclusion, E. granulosus is still present in sheep and dogs but at low prevalences. The increasing presence of T. hydatigena however, indicates that control measures are defective in some areas and there is potential for a re-emergence of CE.

Molecular characterization of Moniezia denticulata (Rudolphi, 1810) and its distinction from M. expansa infecting sheep and goats raised in the north and north-western regions of India.

The tapeworms of Moniezia spp. are heteroxenous parasites and their adult forms occur in ruminants' alimentary tract. They steal a significant portion of hosts' nourishment initiating monieziasis, thereby inflicting economic losses in animal rearing. Despite their high economic importance, the molecular characterization and taxonomic status of these parasites have remained poorly understood. In the present study, cestodes were isolated from the sheep and goats' intestines and were stained with Gower's carmine. Upon careful evaluation of morphological characters, 2 species Moniezia denticulata and Moniezia expansa were identified. The genomic DNA was extracted and polymerase chain reaction (PCR) amplified targeting regions of mitochondrial cytochrome c oxidase subunit 1 (cox1), small subunit ribosomal RNA (SSU rRNA) and internal transcribed spacer 1­5.8S rRNA (ITS1­5.8S rRNA) genes followed by sequencing. The partial sequences of cox1, SSU rRNA and ITS1­5.8S rRNA genes of M. denticulata generated in the present study revealed that even though they share high similarities with M. benedeni (93.2% cox1; 92.6% SSU rRNA; 84.70% ITS1­5.8S rRNA) and M. expansa (88.85% cox1; 92.27% SSU rRNA; 81.70% ITS1­5.8S rRNA), they are not identical to them. In the maximum likelihood phylogenetic trees, M. denticulata and M. expansa consistently appeared as distinct species from each other. The high values of pairwise divergence between these 2 species collected in the present study confirmed their separate identity. The present study reports the first molecular characterization of M. denticulata with reference to M. expansa infecting sheep and goats in India.

Histologic lesions of cestodiasis in octopuses.

Parasitism of cephalopods is common, including infection with Aggregata spp., Ichthyobodo spp., dicyemids, cestodes of the orders Tetraphyllidea and Trypanorhynchidea, and various crustaceans. Cestodiasis in octopuses is reported, although a full histologic description of lesions has not been previously described. Cestodiasis was identified in 10 octopuses of 4 different species, which included 4 common octopuses (Octopus vulgaris), 3 Caribbean reef octopuses (Octopus briareus), 2 two-spot octopuses (Octopus bimaculoides), and 1 giant Pacific octopus (Enteroctopus dofleini). Larval cestodes were present in the cecum (n = 5), intestines (n = 4), digestive gland (n = 3), chitinous alimentary tract (n = 2), renal appendage (n = 1), and salivary duct (n = 1). In 5 cases, larval cestodes invaded tissue and were associated with hemocytic inflammation and tracts of necrotic tissue in the intestines (n = 3), digestive gland (n = 3), and/or renal appendage (n = 1). When present in the chitinous alimentary tract (esophagus, stomach) or cecum, larval cestodes were in the central lumen and not associated with lesions. One adult cestode was identified in the mantle cavity and was not associated with lesions. Other common concurrent parasitic infections included enteric Aggregata spp. infection, branchial Rickettsia-like organism infection, enteric nematodiasis, and an arthropod-associated branchitis.

Neoskrjabinolepis paradoxa n. sp. from shrews on Sakhalin Island, Russia, with an amended diagnosis of Neoskrjabinolepis Spassky, 1947 (Cestoda: Cyclophyllidea: Hymenolepididae), a key, and a review on geographical distribution of the species.

A taxonomic review was performed on cestodes of the genus Neoskrjabinolepis Spassky, 1947 that parasitize different species of Sorex shrews in different regions of the northern Palearctic and in the Nearctic (Alaska, USA). Information on Palearctic Neoskrjabinolepis cestodes published in various articles is summarized. An overview of the geographical distribution of the Neoskrjabinolepis species is also presented. Currently, the genus includes 17 species. In the European part of the Palearctic, four species of the genus are registered; in the Asian part, 13 species; and on the American continent (Seward Peninsula, Alaska, USA), two species. Descriptions, illustrations, and differential diagnoses are given for a new species of Neoskrjabinolepis, i.e. N. paradoxa n. sp., which was found in shrews Sorex unguiculatus Dobson and S. caecutiens Laxmann on Sakhalin Island. A unique feature of the new species is irregularly alternating genital pores in the uterus series in the strobila. Amended new differential features (positioning of the uterus relative to osmoregulatory canals and alternation of genital pores) of genus diagnosis and an identification key for Neoskrjabinolepis spp. are presented.

Host phenotype and microbiome vary with infection status, parasite genotype, and parasite microbiome composition.

A growing literature demonstrates the impact of helminths on their host gut microbiome. We investigated whether the stickleback host microbiome depends on ecoevolutionary variables by testing the impact of exposure to the cestode parasite Schistocephalus solidus with respect to infection success, host genotype, parasite genotype, and parasite microbiome composition. We observed constitutive differences in the microbiome of sticklebacks of different origin, and those differences increased when sticklebacks exposed to the parasite resisted infection. In contrast, the microbiome of successfully infected sticklebacks varied with parasite genotype. More specifically, we revealed that the association between microbiome and immune gene expression increased in infected individuals and varied with parasite genotype. In addition, we showed that S. solidus hosts a complex endomicrobiome and that bacterial abundance in the parasite correlates with expression of host immune genes. Within this comprehensive analysis we demonstrated that (i) parasites contribute to modulating the host microbiome through both successful and unsuccessful infection, (ii) when infection is successful, the host microbiome varies with parasite genotype due to genotype-dependent variation in parasite immunomodulation, and (iii) the parasite-associated microbiome is distinct from its host and impacts the host immune response to infection.

The timing and development of infections in a fish-cestode host-parasite system.

The cestode Schistocephalus solidus is a common parasite in freshwater threespine stickleback populations, imposing strong fitness costs on their hosts. Given this, it is surprising how little is known about the timing and development of infections in natural stickleback populations. Previous work showed that young-of-year stickleback can get infected shortly after hatching. We extended this observation by comparing infection prevalence of young-of-year stickleback from 3 Alaskan populations (Walby, Cornelius and Wolf lakes) over 2 successive cohorts (2018/19 and 2019/20). We observed strong variation between sampling years (2018 vs 2019 vs 2020), stickleback age groups (young-of-year vs 1-year-old) and sampling populations.

Cestodes in the genomic era.

The first cestode genomes were obtained by an international consortium led by the Wellcome Sanger Institute that included representative institutions from countries where the sequenced parasites have been studied for decades, in part because they are etiological agents of endemic diseases (Argentina, Uruguay, Mexico, Canada, UK, Germany, Switzerland, Ireland, USA, Japan, and China). After this, several complete genomes were obtained reaching 16 species to date. Cestode genomes have smaller relative size compared to other animals including free-living flatworms. Moreover, the features genome size and repeat content seem to differ in the two analyzed orders. Cyclophyllidean species have smaller genomes and with fewer repetitive content than Diphyllobothriidean species. On average, cestode genomes have 13,753 genes with 6 exons per gene and 41% GC content. More than 5,000 shared cestode proteins were accurately annotated by the integration of gene predictions and transcriptome evidence being more than 40% of these proteins of unknown function. Several gene losses and reduction of gene families were found and could be related to the extreme parasitic lifestyle of these species. The application of cutting-edge sequencing technology allowed the characterization of the terminal sequences of chromosomes that possess unique characteristics. Here, we review the current status of knowledge of complete cestode genomes and place it within a comparative genomics perspective. Multidisciplinary work together with the implementation of new technologies will provide valuable information that can certainly improve our chances to finally eradicate or at least control diseases caused by cestodes.

Dipylidium caninum draft genome - a new resource for comparative genomic and genetic explorations of flatworms.

Here, we present a draft genome of the tapeworm Dipylidium caninum (family Dipylidiidae) and compare it with other cestode genomes. This draft genome of D. caninum is 110 Mb in size, has a repeat content of ~13.4% and is predicted to encode ~10,000 protein-coding genes. We inferred excretory/secretory molecules (representing the secretome), other key groups of proteins (including peptidases, kinases, phosphatases, GTPases, receptors, transporters and ion-channels) and predicted potential intervention targets for future evaluation. Using 144 shared single-copy orthologous sequences, we investigated the genetic relationships of cestodes for which nuclear genomes are available. This study provides first insights into the molecular biology of D. caninum and a new resource for comparative genomic and genetic explorations of this and other flatworms.

No strong associations between temperature and the host-parasite interaction in wild stickleback.

As climate change progresses, thermal stress is expected to alter the way that host organisms respond to infections by pathogens and parasites, with consequences for the fitness and therefore population processes of both host and parasite. The authors used a correlational natural experiment to examine how temperature differences shape the impact of the cestode parasite Schistocephalus solidus on its host, the three-spined stickleback (Gasterosteus aculeatus). Previous laboratory work has found that high temperatures benefit S. solidus while being detrimental to the stickleback. The present study sought to emulate this design in the wild, repeatedly sampling naturally infected and uninfected fish at matched warmer and cooler locations in the Baltic Sea. In this wild study, the authors found little evidence that temperature was associated with the host-parasite interaction. Although infection reduced host condition and reproductive status overall, these effects did not vary with temperature. Host fitness indicators correlated to some extent with temperature, with cooler capture sites associated with larger size but warmer sites with improved reproductive potential. Parasite fitness (prevalence or size) was not correlated with temperature at the capture site. These mismatches between laboratory and field outcomes illustrate how findings from well-controlled laboratory experiments may not fully reflect processes in more variable natural settings. Nonetheless, the findings of this study indicate that temperature can influence host fitness regardless of infection, with potential consequences for both host demography and parasite transmission dynamics in this complex system.

Determinants of diversity and composition of the tapeworm fauna of blue sharks, Prionace glauca: a geographical and host-specificity analysis.

Blue sharks, Prionace glauca, are cosmopolitan, extremely vagile sharks and the species among elasmobranchs for which most surveys containing tapeworm community data are available worldwide. In this study we report on the tapeworm fauna of three samples of blue sharks (n = 37) from two new regions (one sample from Galicia, north-east Atlantic, and two from Valencia, western Mediterranean), and compared it with previous studies, assessing the relative role of the ecological and evolutionary factors in structuring local tapeworm assemblages. Nine cestode taxa were identified, of which four included adult specimens, that is, Platybothrium auriculatum, Prosobothrium armigerum, Anthobothrium caseyi and Molicola horridus. The abundance of these species, and Brillouin's diversity index, differed significantly among samples without a clear geographical signal. A comparison with six previous surveys revealed that tapeworm assemblages were composed of the same 'core' taxa, with mean species richness typically ranging from two to four species. Global records of adult tapeworms in blue sharks included: 15 taxa identified at species level, of which only eight (generalist trypanorhynchs) were shared with other sympatric host species; five mostly with other carcharhinids; and three with large lamnid sharks sharing the blue sharks' habitat. The composition of tapeworm communities of blue sharks is thus highly constrained by strong host specificity, with composition and abundance varying across localities depending on idiosyncratic environmental conditions.

Ligula Intestinalis Infection in a Native Leuciscid Hybrid (Alburnus Derjugini x Squalius Orientalis) in The Kürtün Dam Lake, Northeast Anatolia.

Taxonomic evaluations are needed to accurately determine the host selection of fish parasites. The present study is a multidisciplinary research in the field of basic and fish diseases sciences. The description of the hybrid species of Squalius orientalis and Alburnus derjugini and infection of Ligula intestinalis in these hybrid fish were reported for the first time from the Kürtün Dam Lake in northeast Turkey. A total of 450 fish were sampled in March, August, and October in 2020 using gillnets. Detailed morphological characteristics (n = 24) were compared to determine the difference among ancestors and hybrid species. The prevalence of L. intestinalis between the sampling periods and the size groups of fish (0 - 10, 11 - 15, and ≥16 cm in length) were examined. Moreover, the highest prevalence of the parasite was observed in October (78.94 %), with a size range of 0 - 10 cm in length (77.8 %). In addition, the total prevalence of the parasite was 48.44 %. The results revealed that most of the diagnostic metric and meristic features of hybrid fish were ranging between the data of S. orientalis and A. derjugini. According to previous reports, when hybrid individuals were compared with their ancestors in terms of prevalence, hybrid individuals were more susceptible to L. intestinalis infections. This study was unique as it provided the first record of L. intestinalis in a hybrid fish population.

Invasive Amirthalingamia macracantha (Cestoda: Cyclophyllidea) larvae infecting tilapia hybrids in Israel: a potential threat for aquaculture.

Larvae (metacestodes) of gryporhynchid tapeworms (Cestoda: Cyclophyllidea) are reported for the first time from the liver of tilapia hybrids (Oreochromis aureus × O. niloticus) reared in earth ponds in northeastern Israel (along the Jordan River). This is the first record of Amirthalingamia macracantha (Joyeux & Baer, 1935), a parasite of cormorants (Phalacrocoracidae), outside Africa and outside the tropics. Larvae found in the liver of tilapias (Cichlidae) were identified to species level because they possessed 20 massive rostellar hooks of 3 types, with the 4 largest hooks measuring almost 500 µm. Molecular data confirmed species identification. The possible route of introduction to Israel of this African parasite, which is large (length up to 2 cm) and potentially pathogenic for cultivated tilapias, is discussed.