Pathogenic helminth infections are responsible for severe health problems and economic losses worldwide. Timely and accurate diagnosis of helminth infections is critical for adopting suitable strategies for pathogen control. Here, we review recent advances in nucleic acid-based diagnostic methods, including polymerase chain reaction, quantitative qPCR, loop-mediated isothermal amplification and recombinase polymerase amplification, and discuss their advantages and disadvantages for diagnosing helminth infections. In addition, we highlight recent advances in biosensors for the detection of nucleic acid biomarkers that can potentially be used for the diagnosis of helminth infection.

Eosinophils are important immune cells that have been implicated in resistance to gastrointestinal nematode (GIN) infections in both naturally and experimentally infected sheep. Proteins of particular importance appear to be IgA-Fc alpha receptor (FcαRI), C-C chemokine receptor type 3 (CCR3), proteoglycan 3 (PRG3, major basic protein 2) and EPX (eosinophil peroxidase). We used known human nucleotide sequences to search the ruminant genomes, followed by translation to protein and sequence alignments to visualize differences between sequences and species. Where a sequence was retrieved for cow, but not for sheep and goat, this was used additionally as a reference sequence. In this review, we show that eosinophil function varies among host species. Consequently, investigations into the mechanisms of ruminant immune responses to GIN should be conducted using the natural host. Specifically, we address differences in protein sequence and structure for eosinophil proteins.

Besnoitia besnoiti is an obligate intracellular apicomplexan protozoan parasite, which causes bovine besnoitiosis. Recently increased emergence within Europe was responsible for significant economic losses in the cattle industry due to the significant reduction of productivity. However, still limited knowledge exists on interactions between B. besnoiti and host innate immune system. Here, B. besnoiti bradyzoites were successfully isolated from tissue cysts located in skin biopsies of a naturally infected animal, and we aimed to investigate for the first time reactions of polymorphonuclear neutrophils (PMN) exposed to these vital bradyzoites. Freshly isolated bovine PMN were confronted to B. besnoiti bradyzoites. Scanning electron microscopy (s.e.m.)- and immunofluorescence microscopy-analyses demonstrated fine extracellular networks released by exposed bovine PMN resembling suicidal NETosis. Classical NETosis components were confirmed via co-localization of extracellular DNA decorated with histone 3 (H3) and neutrophil elastase (NE). Live cell imaging by 3D holotomographic microscopy (Nanolive®) unveiled rapid vital NETosis against this parasite. A significant increase of autophagosomes visualized by specific-LC3B antibodies and confocal microscopy was observed in B. besnoiti-stimulated bovine PMN when compared to non-stimulated group. As such, a significant positive correlation (r = 0.37; P = 0.042) was found between B. besnoiti-triggered suicidal NETosis and autophagy. These findings suggest that vital- as well as suicidal-NETosis might play a role in early innate host defence mechanisms against released B. besnoiti bradyzoites from tissue cysts, and possibly hampering further parasitic replication. Our data generate first hints on autophagy being associated with B. besnoiti bradyzoite-induced suicidal NETosis and highlighting for first time occurrence of parasite-mediated vital NETosis.

Specimens of Stylops advarians were sampled by collecting foraging bees of Andrena milwaukeensis along the South Saskatchewan River within Saskatoon, Saskatchewan. As the foraging season progressed from early May till late June over three consecutive years (2016–2018), most stylopized bees possessed endoparasitic adult (neotenic) females of S. advarians protruding from the bee gaster's dorsum. In contrast, very few adult bees stylopized by male puparia, and no free-living males, were encountered. Over the sampling period, prevalence remained around 22% each year; mean intensity was 1.2 (range of 1–3 female parasites per bee); and parasite abundance was 0.27. Also newly reported for Stylops is the occurrence of one bee bearing four Stylops (two neotenic females and two males with puparia), plus another bee with a male puparium extruded from its gaster's sternites. Around 2 May each year, a high proportion of the earliest captured female bees were stylopized. However, non-stylopized female bees typically were not encountered until about 10 days later, suggesting the parasites manipulate female bee hosts to emerge earlier, in close synchrony to male bee emergence. First-instar larvae of S. advarians appeared from 22–25 May, indicating that adults of S. advarians matured and mated at similar times each season.

The epicontinental fauna of the Iberian Peninsula is strongly influenced by its geographical history. As the possibilities for dispersion of organisms into and from this region were (and still are) limited, the local fauna consists almost exclusively of endemic species. Almost all Iberian freshwater fishes of the families Leuciscidae and Cyprinidae are endemic and on-going research on these taxa continually uncovers new species. Nevertheless, information on their host-specific parasites remains scarce. In this study, we investigate the diversity and phylogenetic relationships in monogeneans of the genus Dactylogyrus (gill ectoparasites specific to cyprinoid fish) in the Iberian Peninsula. Twenty-two species were collected and identified from 19 host species belonging to Cyprinidae and Leuciscidae. A high degree of endemism was observed, with 21 Dactylogyrus species reported from Iberia only and a single species, D. borealis, also reported from other European regions. Phylogenetic analysis split the endemic Iberian Dactylogyrus into two well-supported clades, the first encompassing Dactylogyrus parasitizing endemic Luciobarbus spp. only, and the second including all Dactylogyrus species of endemic leuciscids and four species of endemic cyprinids. Species delimitation analysis suggests a remarkable diversity and existence of a multitude of cryptic Dactylogyrus species parasitizing endemic leuciscids (Squalius spp. and representatives of Chondrostoma s.l.). These results suggest a rapid adaptive radiation of Dactylogyrus in this geographically isolated region, closely associated with their cyprinoid hosts. Moreover, phylogenetic analysis supports that Dactylogyrus parasites colonized the Iberian Peninsula through multiple dispersion events.

Swimmer's itch (SI) is a painful rash caused by skin penetration by free-swimming infectious cercariae of avian schistosomes, snail-borne helminth parasites related to the causative agents of human schistosomiasis. The goal of this study was to determine if commonly collected environmental data could be used to predict daily fluctuations in SI incidence at an inland beach in northwestern Michigan. Lifeguards collected daily data over four summers, including the number of self-reported SI cases, total swimmers, water temperature, wind speed and wind direction. Mixed-effects binomial regression revealed that wind direction, wind speed and time of day were the best predictors of daily SI risk. Swimmers entering the water in the morning or on days with direct onshore wind perpendicular to the shoreline had the greatest SI risk. However, there was a negative effect of wind speed after accounting for direction, where SI risk was greatest on days with a gentle breeze originating directly offshore. These results suggest that at this beach, direct onshore winds generate a surface-water current that causes SI cercariae to aggregate in the shallow waters used by swimmers. Data are needed from additional sites to confirm whether the onshore wind is a generally important driver of SI incidence.

Factors such as the particular combination of parasite–mosquito species, their co-evolutionary history and the host's parasite load greatly affect parasite transmission. However, the importance of these factors in the epidemiology of mosquito-borne parasites, such as avian malaria parasites, is largely unknown. Here, we assessed the competence of two mosquito species [Culex pipiens and Aedes (Ochlerotatus) caspius], for the transmission of four avian Plasmodium lineages (Plasmodium relictum SGS1 and GRW11 and Plasmodium cathemerium-related lineages COLL1 and PADOM01) naturally infecting wild house sparrows. We assessed the effects of parasite identity and parasite load on Plasmodium transmission risk through its effects on the transmission rate and mosquito survival. We found that Cx. pipiens was able to transmit the four Plasmodium lineages, while Ae. caspius was unable to transmit any of them. However, Cx. pipiens mosquitoes fed on birds infected by P. relictum showed a lower survival and transmission rate than those fed on birds infected by parasites related to P. cathemerium. Non-significant associations were found with the host–parasite load. Our results confirm the existence of inter- and intra-specific differences in the ability of Plasmodium lineages to develop in mosquito species and their effects on the survival of mosquitoes that result in important differences in the transmission risk of the different avian malaria parasite lineages studied.

The myxozoan genus Unicapsula Davis, 1924 (Myxosporea: Multivalvulida: Trilosporidae) is characterized as having one functional polar capsule (PC) and two rudimentary PCs in a three-valved myxospore. The plasmodia of Unicapsula spp. grow either in the myofibres or in the gills, oesophageal walls and urinary organs of marine fish. Few studies have investigated the taxonomy of Unicapsula spp. including the type species Unicapsula muscularis. Accordingly, the taxonomy of the genus was explored in the present study by using 15 new isolates of seven Unicapsula spp. (U. muscularis, U. galeata, U. andersenae, U. pyramidata, U. pflugfelderi, and two new species) that had formed pseudocysts in the trunk myofibres of commercial fish collected in southern China and Japan from November 2015 to January 2019. Two new species Unicapsula trigona n. sp., and Unicapsula motomurai n. sp. exhibited unique myxospore morphologies (semi-triangular and spherical myxospores, respectively) and 18S and 28S rDNA sequences that were distinct from those of the other Unicapsula spp. Phylogenetic analysis of the 18S and 28S rDNA sequences confirmed the monophyletic status of Unicapsula.

The CXCR3 chemokine CXCL10 or IFN-γ inducible protein 10 (IP-10) has been identified as an important biomarker of cerebral malaria (CM) mortality in children. Studies in mouse malaria infection models have shown that CXCL10 blockade alleviates brain intravascular inflammation and protects infected mice from CM. Despite the key role that CXCL10 plays in the development of CM, the leucocytic sources of CXCL10 in response to human malaria are not known. Here we investigated CXCL10 responses to Plasmodium falciparum in peripheral blood mononuclear cells (PBMCs). We found that PBMCs from malaria-unexposed donors produce CXCL10 in response to P. falciparum and that this response is IFN-γ-dependent. Moreover, CD14+ monocytes were identified as the main leucocytic sources of CXCL10 in peripheral blood, suggesting an important role for innate immune responses in the activation of this pathway involved in the development of symptomatic malaria.

This study provides insights about the diversity, prevalence and distribution of alpine wild galliformes gastrointestinal parasite community, trying to fill a gap in the scientific information currently available in scientific literature. The analysis included three host species: 77 rock partridge (Alectoris graeca saxatilis), 83 black grouse (Tetrao tetrix tetrix) and 26 rock ptarmigan (Lagopus muta helveticus) shot during the hunting seasons 2008–2015. Parasites isolated were Ascaridia compar, Capillaria caudinflata and cestodes. The rock ptarmigan was free from gastrointestinal parasites, whereas the most prevalent helminth (37%) was A. compar in both black grouse and rock partridge. C. caudinflata occurrence was significantly higher in black grouse (prevalence = 10%, mean abundance = 0.6 parasites/sampled animal) than in rock partridge (prevalence = 1.20%, mean abundance = 0.01 parasites/sampled animal). Significant differences were detected among hunting districts. A. compar was found with a significant higher degree of infestation in the hunting districts in the northern part of the study area whereas cestodes abundance was higher in Lanzo Valley. Quantitative analysis of risk factors was carried out using a generalized linear model (GLM) only on the most common parasite (A. compar). Latitude was the only factors associated with infestation risk (OR = 52.4). This study provides information on the composition and variability of the parasite community in the alpine Galliformes species.

Lernaeenicus radiatus, a mesoparasitic pennellid copepod, has long been known in the northwest Atlantic with metamorphosed females infecting the muscle of marine fish. The study herein is the first to identify a definitive first host, black sea bass Centropristis striata, for L. radiatus supporting larval development to adults and sexual reproduction in the gills. This finding suggests a two-host life cycle for L. radiatus, with black sea bass as the first host. Heavy infections in the gill were associated with considerable pathology related to a unique and invasive attachment process that penetrated the gill and selectively attached to the gill filament cartilage. The morphology of the developing copepod was highly conserved with that of a related pennellid copepod, Lernaeocera branchialis, though was distinguished by the attachment process, unique pigmentation and other morphologic features described herein. Sequencing the small and large subunits of the ribosomal RNA and mitochondrial cytochrome c oxidase subunit I genes demonstrated L. radiatus to share closer identities with Lernaeocera and Haemobaphes spp. pennellid copepods rather than other Lernaeenicus spp. available in GenBank to date. Taxonomy of L. radiatus is discussed in relation to life cycles, tissue tropism, morphology and genetics of other closely related pennellid copepods.

We compared lizard endoparasite assemblages between the Atlantic Forest and naturally isolated forest enclaves to test the ecological release hypothesis, which predicts that host specificity should be lower (large niche breadth) and parasite abundance should be greater for parasites from isolated forest enclaves (poor assemblages) than for parasites from the coastal Atlantic Forest (rich assemblages). Parasite richness per specimen showed no difference between the isolated and non-isolated areas. Parasite abundance did not differ between the isolated and non-isolated areas but showed a positive relationship with parasite richness considering all areas (isolated and non-isolated). Furthermore, host specificity was positively related to parasite richness. Considering that host specificity is inversely proportional to the host range infected by a parasite, our results indicate that in assemblages with greater parasite richness, parasites tend to infect a smaller range of hosts than do those in simple assemblages. In summary, our study partially supports the ecological release hypothesis: in assemblages with greater parasite richness, lizard parasites from Atlantic Forest are able to increase their parasite abundance (per host), possibly through facilitated infection; however, the amplitude of infected hosts only expands in poor assemblages (lower parasite richness).

As a consequence of axenic growth and the elimination of accompanying bacterial flora, Entamoeba histolytica virulence decreases rapidly, and pathogenicity is lost. This paper evaluated the impact of vitamin supplementation on the pathogenicity of E. histolytica. Growth of E. histolytica trophozoites, cultured axenically in PEHPS (a Spanish acronym for the main ingredients – casein peptone, liver, pancreas extract and bovine serum) medium, with or without vitamins, exhibited a similar growth rate. However, the vitamin-enriched PEHPS preparations expressed 2.65 times more haemolytic activity (at 60 min: 98 vs 48%, P < 0.05), 2.5 times more phospholipase A2 activity at 150 min of incubation and generated more hepatic abscesses (88 vs 60%, P = 0.05) than the preparations without vitamins. The haemolytic and phospholipase A2 activity for the PEHPS − V preparations were restored following vitamin supplementation with A and D. These data highlight, for the first time, that vitamins and specifically vitamin A and D were essential for the recovery of amoebic virulence, lost through axenic growth.