Although Nematodirus battus is a serious threat to the health and survival of young lambs, there are few options to control this parasite. Bayesian Monte Carlo Markov Chain modelling with a zero-inflated Poisson distribution was used to estimate the heritability of egg counts in both June and July for each of five consecutive cohorts of 200 Scottish Blackface lambs. In one of the 10 analyses, the results failed the diagnostic tests. In seven of the analyses, there was no convincing evidence that the variation in egg counts was heritable. In the 2 years of high infection, the heritability was approximately 0.4 in June but the estimates lacked precision and the 95% highest posterior density credible intervals ranged from just above zero to 0.7. Selective breeding for resistance to N. battus will be difficult because genetically resistant or susceptible lambs cannot be consistently identified by phenotypic markers.

Blood flukes of freshwater fish are understudied worldwide. Consequently, genetic information and data on their intramolluscan stages are scarce. In the current study, freshwater limpets of the genus Burnupia (Burnupiidae) from South Africa were examined for digeneans. Of 1645 specimens, 3.10% were infected by Sanguinicolidae larvae. Four sanguinicolids were distinguished by body size, number of penetration glands, tegumental spines’ patterns and relative sizes of the finfolds on the body and furcae. Analyses of 28S, 18S and ITS rDNA sequences showed that the morphotypes were distinct from each other and from sanguinicolids whose genetic data are available. The present study is the first genetic characterization of sanguinicolids from Africa. Phylogenetic reconstruction revealed that the present species clustered with a sanguinicolid from Poland and were sister to Sanguinicola and Pseudosanguinicola from Russia and USA, respectively. The results indicate that the current species represent an unknown genus. What is more, blood fluke sequences from East Africa (presumed to be sanguinicolids), were distant from Sanguinicolidae and showed a closer relationship with acipensericolids from the USA. Freshwater fish blood flukes seem to be more diverse than previously recorded and use species of at least 13 gastropod families as intermediate hosts.

Perkinsus olseni is an industrially significant protozoan parasite of Manila clam, Ruditapes philippinarum. So far, various media, based on Dulbecco's Modified Eagle Medium and Ham's F-12 nutrient mixture with supplementation of fetal bovine serum (FBS), have been developed to proliferate the parasitizing trophozoite stage of P. olseni. The present study showed that P. olseni did not proliferate in FBS-deficient Perkinsus broth medium (PBMΔF), but proliferated well in PBMΔF supplemented with tissue extract of host Manila clams, indicating that FBS and Manila clam tissue contained molecule(s) required for P. olseni proliferation. Preliminary characterization suggested that the host-derived molecule(s) was a heat-stable molecule(s) with a molecular weight of less than 3 kDa, and finally a single molecule required for the proliferation was purified by high-performance liquid chromatography processes. High-resolution electrospray ionization mass spectrometry and nuclear magnetic resonance analyses identified this molecule as glycine betaine (=trimethylglycine), and the requirement of this molecule for P. olsseni proliferation was confirmed by an assay using chemically synthesized, standard glycine betaine. Although glycine betaine was required for the proliferation of all examined Perkinsus species, supplementation of glycine betaine precursors, such as choline and betaine aldehyde, enhanced the proliferation of 4 Perkinsus species (P. marinus, P. chesapeaki, P. mediterraneus and P. honshuensis), but not of 2 others (P. olseni and P. beihaiensis). Thus, it was concluded that the ability to biosynthesise glycine betaine from its precursors varied among Perkinsus species, and that P. olseni and P. beihaiensis lack the ability required to biosynthesize glycine betaine for proliferation.

Schistosomiasis, a parasite infectious disease caused by Schistosoma japonicum, often leads to egg granuloma and fibrosis due to the inflammatory reaction triggered by egg antigens released in the host liver. This study focuses on the role of the egg antigens CP1412 protein of S. japonicum (SjCP1412) with RNase activity in promoting liver fibrosis. In this study, the recombinant egg ribonuclease SjCP1412, which had RNase activity, was successfully prepared. By analysing the serum of the population, it has been proven that the anti-SjCP1412 IgG in the serum of patients with advanced schistosomiasis was moderately correlated with liver fibrosis, and SjCP1412 may be an important antigen associated with liver fibrosis in schistosomiasis. In vitro, the rSjCP1412 protein induced the human liver cancer cell line Hep G2 and liver sinusoidal endothelial cells apoptosis and necrosis and the release of proinflammatory damage-associated molecular patterns (DAMPs). In mice infected with schistosomes, rSjCP1412 immunization or antibody neutralization of SjCP1412 activity significantly reduced cell apoptosis and necroptosis in liver tissue, thereby reducing inflammation and liver fibrosis. In summary, the SjCP1412 protein plays a crucial role in promoting liver fibrosis during schistosomiasis through mediating the liver cells apoptosis and necroptosis to release DAMPs inducing an inflammatory reaction. Blocking SjCP1412 activity could inhibit its proapoptotic and necrotic effects and alleviate hepatic fibrosis. These findings suggest that SjCP1412 may be served as a promising drug target for managing liver fibrosis in schistosomiasis japonica.

Trichomonas vaginalis is a parasite of the human urogenital tract and the causative agent of trichomoniasis, a sexually transmitted disease of worldwide importance. This parasite is usually found as a motile flagellated trophozoite. However, when subjected to stressful microenvironmental conditions, T. vaginalis trophozoites can differentiate into peculiar cyst-like stages, which exhibit notable physiological resistance to unfavourable conditions. Although well documented in morphological and proteomic terms, patterns of gene expression changes involved in the cellular differentiation into cyst-like stages are mostly unknown. The real-time reverse transcription polymerase chain reaction (RT-qPCR) is recognized as a sensitive and accurate method for quantification of gene expression, providing fluorescence-based data that are proportional to the amount of a target RNA. However, the reliability of relative expression studies depends on the validation of suitable reference genes, which RNAs exhibit a minimum of variation between tested conditions. Here, we attempt to determine suitable reference genes to be used as controls of invariant expression during cold-induced in vitro differentiation of T. vaginalis trophozoites into cyst-like forms. Furthermore, we reveal that the mRNA from the meiotic recombinase Dmc1 is upregulated during this process, indicating that cryptic sexual events may take place in cyst-like stages of T. vaginalis.

Dermoergasilus madagascarensis n. sp. is described from the gills of Paretroplus polyactis, an endemic cichlid fish in Madagascar, using a combined morphological (light microscopy and SEM) and molecular approach (partial 18S rDNA, 28S rDNA, and COI sequences). The new species is characterized mainly by possessing: (i) roughly pentagonal cephalosome; (ii) antennal endopodal segments covered with slightly inflated membrane; (iii) maxillule bearing 2 equally long outer setae and a minute inner seta; (iv) interpodal sternites of swimming legs ornamented with 3–4 rows of spinules; (v) genital segment and first abdominal somite both barrel-shaped; and (vi) a caudal ramus projecting into a digitiform process with inconspicuous terminal seta and bearing 3 terminal setae. The obtained DNA sequences of Malagasy species represent the first molecular data for species of Dermoergasilus. The 28S rDNA phylogeny showed the affiliation of D. madagascarensis n. sp. to Ergasilidae and its sister relationship with cosmopolitan Ergasilus sieboldi von Nordmann, 1832. The first checklist for all species of Dermoergasilus is provided.

There are no scientific data available on the occurrence of the Echinococcus granulosus sensu lato (s.l.) cluster in definitive hosts (domestic dogs), intermediate hosts (domestic livestock) nor humans in Cape Verde. In this pilot study, environmental dog fecal samples (n = 369) were collected around food markets, official slaughterhouses, as well as home and small business slaughter spots in 8 of the 9 inhabited islands from the Cape Verde archipelago, between June 2021 and March 2022. Additionally, during the same period, 40 cysts and tissue lesions were opportunistically collected from 5 islands, from locally slaughtered cattle (n = 7), goats (n = 2), sheep (n = 1) and pigs (n = 26). Genetic characterization by a multiplex polymerase chain reaction assay targeting the 12S rRNA gene confirmed the presence of E. granulosus s.l. in fecal and tissue material. In total, 17 cyst samples from Santiago (n = 9), Sal (n = 7) and São Vicente (n = 1) and 8 G6/G7-positive dog fecal samples from Santiago (n = 4) and Sal (n = 4) were identified as E. granulosus s.l. G7 by sequence analysis (nad2, nad5 and nad1 genes). This study discloses the transmission of E. granulosus s.l. G7, in pig, cattle and dog in Cape Verde.

Circadian rhythms are timekeeping mechanisms responsible for an array of biological processes. Disruption of such cycles can detrimentally affect animal health. Circadian rhythms are critical in the co-evolution of host–parasite systems, as synchronization of parasite rhythms to the host can influence infection dynamics and transmission potential. This study examines the circadian rhythms in behaviour and activity of a model fish species (Poecilia reticulata) in isolation and in shoals, both when uninfected and infected with an ectoparasite (Gyrodactylus turnbulli). Additionally, the rhythmical variance of parasite activity under different light conditions as well as rhythmical variance in parasite transmissibility was explored. Overall, infection alters the circadian rhythm of fish, causing nocturnal restlessness. Increased activity of gyrodactylids on the host's skin at night could potentially contribute to this elevated host activity. Whilst migration of gyrodactylids across the host's skin may have caused irritation to the host resulting in nocturnal restlessness, the disruption in guppy activity rhythm caused by the expression of host innate immunity cannot be excluded. We discuss the wider repercussions such behavioural responses to infection have for host health, the implications for animal behaviour studies of diurnal species as well as the application of chronotherapeutic approaches to aquaculture.

Plasmodium coatneyi has been proposed as an animal model for human Plasmodium falciparum malaria as it appears to replicate many aspects of pathogenesis and clinical symptomology. As part of the ongoing evaluation of the rhesus macaque model of severe malaria, a detailed ultrastructural analysis of the interaction between the parasite and both the host erythrocytes and the microvasculature was undertaken. Tissue (brain, heart and kidney) from splenectomized rhesus macaques and blood from spleen-intact animals infected with P. coatneyi were examined by electron microscopy. In all three tissues, similar interactions (sequestration) between infected red blood cells (iRBC) and blood vessels were observed with evidence of rosette and auto-agglutinate formation. The iRBCs possessed caveolae similar to P. vivax and knob-like structures similar to P. falciparum. However, the knobs often appeared incompletely formed in the splenectomized animals in contrast to the intact knobs exhibited by spleen intact animals. Plasmodium coatneyi infection in the monkey replicates many of the ultrastructural features particularly associated with P. falciparum in humans and as such supports its use as a suitable animal model. However, the possible effect on host–parasite interactions and the pathogenesis of disease due to the use of splenectomized animals needs to be taken into consideration.

Invertebrate host–parasite associations are one of the keystones in order to understand vector-borne diseases. The study of these specific interactions provides information not only about how the vector is affected by the parasite at the gene-expression level, but might also reveal mosquito strategies for blocking the transmission of the parasites. A very well-known vector for human malaria is Anopheles gambiae. This mosquito species has been the main focus for genomics studies determining essential key genes and pathways over the course of a malaria infection. However, to-date there is an important knowledge gap concerning other non-mammophilic mosquito species, for example some species from the Culex genera which may transmit avian malaria but also zoonotic pathogens such as West Nile virus. From an evolutionary perspective, these 2 mosquito genera diverged 170 million years ago, hence allowing studies in both species determining evolutionary conserved genes essential during malaria infections, which in turn might help to find key genes for blocking malaria cycle inside the mosquito. Here, we extensively review the current knowledge on key genes and pathways expressed in Anopheles over the course of malaria infections and highlight the importance of conducting genomic investigations for detecting pathways in Culex mosquitoes linked to infection of avian malaria. By pooling this information, we underline the need to increase genomic studies in mosquito–parasite associations, such as the one in Culex–Plasmodium, that can provide a better understanding of the infection dynamics in wildlife and reduce the negative impact on ecosystems.

Model parasite species, whose entire life cycle can be completed in the laboratory and maintained for multiple generations, have played a fundamental role in our understanding of host–parasite interactions. Yet, keeping parasites in laboratory conditions may expose them to unnatural evolutionary pressures, and using laboratory cultures for research is therefore not without limitations. Using 2 widely-used model helminth species, the cestode Hymenolepis diminuta and the nematode Heligmosomoides polygyrus, I illustrate the caution needed when interpreting experimental results on model species. I first review more than 1200 experimental studies published on these species in the past 4 decades, to determine which research areas they have contributed to. This is followed by an examination of the institutional laboratory cultures that have provided the parasites used in these studies. Some of these have persisted for decades and accounted for a substantial proportion of published studies, whereas others have been short-lived. Using information provided by the curators of active cultures, I summarize data on their origins and maintenance conditions. Finally, I discuss how laboratory cultures may have been subject to the influence of evolutionary genetic processes, such as founder effects, genetic drift and inbreeding. I also address the possibility that serial passage through laboratory hosts across multiple generations has exerted artificial selection on several parasite traits, resulting in genetic and phenotypic divergence among laboratory cultures, and between these cultures and natural parasite populations. I conclude with recommendations for the continued usage of laboratory helminth cultures aimed at maximizing their important contribution to parasitological research.

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 1–5.8S rRNA (ITS1–5.8S rRNA) genes followed by sequencing. The partial sequences of cox1, SSU rRNA and ITS1–5.8S 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% ITS1–5.8S rRNA) and M. expansa (88.85% cox1; 92.27% SSU rRNA; 81.70% ITS1–5.8S 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.