Tuft cell acetylcholine is released into the gut lumen to promote anti-helminth immunity

Upon parasitic helminth infection, activated intestinal tuft cells secrete interleukin-25 (IL-25), which initiates a type 2 immune response during which lamina propria type 2 innate lymphoid cells (ILC2s) produce IL-13. This causes epithelial remodeling, including tuft cell hyperplasia, the function of which is unknown. We identified a cholinergic effector function of tuft cells, which are the only epithelial cells that expressed choline acetyltransferase (ChAT). During parasite infection, mice with epithelial-specific deletion of ChAT had increased worm burden, fitness, and fecal egg counts, even though type 2 immune responses were comparable. Mechanistically, IL-13-amplified tuft cells release acetylcholine (ACh) into the gut lumen. Finally, we demonstrated a direct effect of ACh on worms, which reduced their fecundity via helminth-expressed muscarinic ACh receptors. Thus, tuft cells are sentinels in naive mice, and their amplification upon helminth infection provides an additional type 2 immune response effector function.

Some trematodes including three new species from freshwater fishes of Venezuela

The present paper comprises a systematic survey of trematodes found in 13 species of freshwater fishes in Venezuela collected in 1992, 1996 and 2001. The following 15 trematode species were recorded: Adults: Genarchella venezuelaensis sp. n., Thometrema dissimilis sp. n., Megacoelium spinicavum Thatcher et Varella, 1981, Doradamphistoma bacuense Thatcher, 1999, Crassicutis cichlasomae Manter, 1936, Parspina carapo Ostrowski de Núñez, Arredonto et Gil de Pertierra, 2011, Phyllodistomoides hoplerythrini sp. n. Larvae (metacercariae): Clinostomatopsis sorbens (Braun, 1899), Clinostomum marginatum (Rudolphi, 1819), C. detruncatum Braun, 1899, Ithyoclinostomum dimorphum (Diesing, 1850), Odhneriotrema microcephala (Travassos, 1922), Tylodelphys sp., Posthodiplostomum sp., Sphincterodiplostomum sp. All these parasites are reported from Venezuela for the first time and many of these findings represent new host records. The new species G. venezuelaensis sp. n., T. dissimilis sp. n. and P. hoplerythrini sp. n. were collected from the accessory respiratory organ of Loricariichthys brunneus (Hancock) (Loricariidae), from the stomach of Hoplerythrinus unitaeniatus (Spix et Agassiz) (Erythrinidae) and from the intestine of H. unitaeniatus, respectively. All parasites are briefly described and illustrated and problems concerning their morphology, taxonomy, hosts and geographical distribution are discussed. Megacoelium spinispecum Thatcher et Varella, 1981 is considered a junior synonym of M. spinicavum Thatcher et Varella, 1981, and Crassicutis opisthoseminis Bravo-Hollis et Arroyo, 1962 as a junior synonym of C. cichlasomae Manter, 1936.

Parasitic helminths of alien invasive anurans in Butuan City, Northeastern Mindanao, Philippines

This study aimed to identify the helminth parasites of invasive anuran species in selected barangays in Butuan City, Philippines. In urbanized areas, invasive species dominate anuran diversity, and one of the primary threats they pose to native wildlife is the transmission of diseases and parasites. Out of the 91 collected individuals of invasive anuran species, Rhinella marina was the most abundant (88 %), followed by Hoplobatrachus rugulosus (12 %) and Kaloula pulchra (3 %). The study identified five species of parasites, with Spirometra sp. being the most prevalent (17.58 %), followed by Echinostoma sp. (16.5 %), Rhabdias bufonis (14.3 %), Cosmocerca sp. (6.6 %), and Strongyloides stercoralis (3.30 %), respectively. Spirometra sp. also had the highest intensity (7.67), followed by Cosmocerca sp. (5), Strongyloides stercoralis (3.33), Rhabdias bufonis (3.30), and Echinostoma sp. (2.73). This parasitological survey revealed that H. rugulosus had the highest prevalence and infection of parasites, and residential areas had the highest parasite prevalence among the habitat types. Adult hosts were found to harbor a higher prevalence and intensity, and male hosts had a higher prevalence. The results highlight the high risk of parasite transmission from anurans to other animals and emphasize the need for the community to control the population of invasive anuran species for the safety of native anurans and to prevent zoonotic transmission to other animals and humans.

Parasitic load of the Pacific mackerel, Scomber japonicus (Pisces: Scombridae) from Northwestern Baja California, Mexico

Globally, the exploitation of small pelagic fish, like Pacific mackerel is of great importance due to food industry demand. However, there are few studies regarding its parasites load and there are no in this geographic zone. This study aimed to assess the parasitic composition, some temporal changes (during spring and summer) in abundance, prevalence and intensity of infection parasitic of the Pacific mackerel (Scomber japonicus) from Todos Santos Bay, Baja California, Mexico. The parasite fauna of the Pacific mackerel consisted of 1930 parasites (1413 in spring and 517 in summer) distributed in the follow taxa: an Tetraphyllidea (Cestoda), Kuhnia scombri (Monogenea), Didymozoidae (Digenea), Anisakis sp. (Nematoda), Rhadinorhynchus sp. (Acanthocephala) and Caligus pelamydis (Copepoda). The nematodes parasite were the most abundant both in spring with a mean abundance of 27.6 parasites and in summer 8.2 parasites compared with the other taxa like Cestoda, Monogenea, Digenea, Acanthocephala and Copepoda (P = 0.003). The mean intensity of the nematodes in spring and summer was 28.1 and 13.4, respectively. The nematodes prevalence was 90 % in spring and 60 % in summer. In general, the parasite load is more abundant in spring than summer. In summer, absence of taxa as Cestoda and Copepoda were registered. Nematode larvae were present in the fish guts mesentery and inside of the stomach, pyloric caeca, intestine. Also the nematodes were found in the liver, muscle and gonads. The most affected organ by nematodes was the intestine mesentery. The most predominant parasite of this study has been Anisakis sp. during spring.

Eosinophil trafficking in allergen-mediated pulmonary inflammation relies on IL-13-driven CCL-11 and CCL-24 production by tissue fibroblasts and myeloid cells

Background

The immunologic mechanisms underlying pulmonary type 2 inflammation, including the dynamics of eosinophil recruitment to the lungs, still need to be elucidated.

Objective

We sought to investigate how IL-13-producing TH2 effector cells trigger eosinophil migration in house dust mite (HDM)-driven allergic pulmonary inflammation.

Methods

Multiparameter and molecular profiling of murine lungs with HDM-induced allergy was investigated in the absence of IL-13 signaling by using IL-13Rα1-deficient mice and separately through adoptive transfer of CD4+ T cells from IL-5-deficient mice into TCRα-/- mice before allergic inflammation.

Results

We demonstrated through single-cell techniques that HDM-driven pulmonary inflammation displays a profile characterized by TH2 effector cell-induced IL-13-dominated eosinophilic inflammation. Using HDM-sensitized IL-13Rα1-/- mice, we found a marked reduction in the influx of eosinophils into the lungs along with a significant downregulation of both CCL-11 and CCL-24. We further found that eosinophil trafficking to the lung relies on production of IL-13-driven CCL-11 and CCL-24 by fibroblasts and Ly6C+ (so-called classical) monocytes. Moreover, this IL-13-mediated eotaxin-dependent eosinophil influx to the lung tissue required IL-5-induced eosinophilia. Finally, we demonstrated that this IL-13-driven eosinophil-dominated pulmonary inflammation was critical for limiting bystander lung transiting Ascaris parasites in a model of allergy and helminth interaction.

Conclusion

Our data suggest that IL-5-dependent allergen-specific TH2 effector cell response and subsequent signaling through the IL-13/IL-13Rα1 axis in fibroblasts and myeloid cells regulate the eotaxin-dependent recruitment of eosinophils to the lungs, with multiple downstream consequences, including bystander control of lung transiting parasitic helminths.

Eco-evolutionary implications of helminth microbiomes

The evolution of helminth parasites has long been seen as an interplay between host resistance to infection and the parasite's capacity to bypass such resistance. However, there has recently been an increasing appreciation of the role of symbiotic microbes in the interaction of helminth parasites and their hosts. It is now clear that helminths have a different microbiome from the organisms they parasitize, and sometimes amid large variability, components of the microbiome are shared among different life stages or among populations of the parasite. Helminths have been shown to acquire microbes from their parent generations (vertical transmission) and from their surroundings (horizontal transmission). In this latter case, natural selection has been strongly linked to the fact that helminth-associated microbiota is not simply a random assemblage of the pool of microbes available from their organismal hosts or environments. Indeed, some helminth parasites and specific microbial taxa have evolved complex ecological relationships, ranging from obligate mutualism to reproductive manipulation of the helminth by associated microbes. However, our understanding is still very elementary regarding the net effect of all microbiome components in the eco-evolution of helminths and their interaction with hosts. In this non-exhaustible review, we focus on the bacterial microbiome associated with helminths (as opposed to the microbiome of their hosts) and highlight relevant concepts and key findings in bacterial transmission, ecological associations, and taxonomic and functional diversity of the bacteriome. We integrate the microbiome dimension in a discussion of the evolution of helminth parasites and identify fundamental knowledge gaps, finally suggesting research avenues for understanding the eco-evolutionary impacts of the microbiome in host-parasite interactions in light of new technological developments.

Spatial parasitology and the unmapped human helminthiases

Helminthiases are a class of neglected tropical diseases that affect at least 1 billion people worldwide, with a disproportionate impact on resource-poor areas with limited disease surveillance. Geospatial methods can offer valuable insights into the burden of these infections, particularly given that many are subject to strong ecological influences on the environmental, vector-borne or zoonotic stages of their life cycle. In this study, we screened 6829 abstracts and analysed 485 studies that use maps to document, infer or predict transmission patterns for over 200 species of parasitic worms. We found that quantitative mapping methods are increasingly used in medical parasitology, drawing on One Health surveillance data from the community scale to model geographic distributions and burdens up to the regional or global scale. However, we found that the vast majority of the human helminthiases may be entirely unmapped, with research effort focused disproportionately on a half-dozen infections that are targeted by mass drug administration programmes. Entire regions were also surprisingly under-represented in the literature, particularly southern Asia and the Neotropics. We conclude by proposing a shortlist of possible priorities for future research, including several neglected helminthiases with a burden that may be underestimated.

New Parasitic Records of Aves: Phasianidae (Alectoris Chukar) in Malakand Division Northern, Pakistan

More than 24,000 species of helminth parasitize wild birds worldwide, and this number is expanding as interest in wildlife parasitology increases. The objective of the current study was to update the baseline of helminthological surveys conducted on chukar partridges (Alectoris chukar) in northern Pakistan. After reviewing the available literature, a parasite-host association checklist was developed. Nematodes (53.8 %) were the most commonly reported parasite, followed by cestodes (15.3 %) and trematodes (15.3 %) respectively. Seventy (70) chukar partridge (Alectoris chukar) distributed across the Malakand division of northern Pakistan were screened for parasitosis during the period from October 2020 to the end of December 2021. Blood samples of all the specimens were screened for haemoprotozoa, the digestive tract was examined for protozoans and helminths. The examined birds were infected with nine different helminth parasite species identified as cestodes (4 species), trematodes (2 species) and 3 species of nematodes. 29 out of 70 birds were infected, with the male and female infection rates being 36 % and 52.1 %, respectively, with a total prevalence of 41.3 %. Among the infected birds 10 (34.4 %) contained cestodes, 2 (6.8 %) contained trematodes and 17 (58.6 %) contained nematodes. Of which Ascaridia galli and Capillaria phasianina recorded the highest prevalence (10 %). While Amoebotaenia cuneate, Choanotaenia infundibulum, Hypoderaeum conoideum, Lyperosomum longicauda recorded the least (1.4 %) respectively. Reporting of Raillietina echinobothrida, Amoebotaenia cuneate and Lyperosomum longicauda constitute new host records. A. cuneate is a new record in the parasitological list in the country. In terms of host's sexuality, the overall figures show no significant changes in infection indices.

A new species of Arostrilepis from Ellobius tancrei (Rodentia: Cricetidae) in Mongolia

Cestodes of the genus Arostrilepis Mas-Coma and Tenora 1997 have a Holarctic distribution with 16 species occurring among 28 species of mostly arvicoline hosts. The type species of the genus is Arostrilepis horrida (von Linstow, 1901), described initially as Taenia horrida von Linstow, 1901, from murine rodents in Lower Saxony (Niedersachsen), Germany. Here we report the first helminth parasite from the mole-vole, Ellobius tancrei , in Mongolia which is the first subterranean rodent known to be infected with Arostrilepis in the Palearctic. In addition, we describe a new species: Arostrilepis batsaikhani n. sp. which most closely resembles A. microtis Gulyaev and Chechulin 1997, differing from this species with a genetic distance of about 4% (using cytochrome-b) and by having distinctly large cirrus spines, testes that are larger and fill the whole segment measured anterior–posterior and larger eggs.

Spatial variation in species' roles in host-helminth networks

Species interactions may vary considerably across space as a result of spatial and environmental gradients. With respect to host-parasite interactions, this suggests that host and parasite species may play different functional roles across the different networks they occur in. Using a global occurrence database of helminth parasites, we examine the conservation of species' roles using data on host-helminth interactions from 299 geopolitical locations. Defining species' roles in a two-dimensional space which captures the tendency of species to be more densely linked within species subgroups than between subgroups, we quantified species' roles in two ways, which captured if and which species' roles are conserved by treating species' utilization of this two-dimensional space as continuous, while also classifying species into categorical roles. Both approaches failed to detect the conservation of species' roles for a single species out of over 38 000 host and helminth parasite species. Together, our findings suggest that species' roles in host-helminth networks may not be conserved, pointing to the potential role of spatial and environmental gradients, as well as the importance of the context of the local host and helminth parasite community. This article is part of the theme issue 'Infectious disease macroecology: parasite diversity and dynamics across the globe'.

Potential Influence of Helminth Molecules on COVID-19 Pathology

In recent months, the parasitology research community has been tasked with investigation of the influence of parasite coinfection on coronavirus disease 2019 (COVID-19) outcomes. Herein, we share our approach to analyze the effect of the trematode Fasciola hepatica as a modulator of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and of COVID-19 pathology.

Helminth parasites occurrence in wild proboscis monkeys (Nasalis larvatus), endemic primates to Borneo Island

BACKGROUND

Nasalis larvatus are well-known attraction for tourists in the mangrove forest of Bako National Park (BNP). Little is known regarding the infestation of helminth parasites in proboscis monkeys. Therefore, the objectives of this study are to determine the prevalence species of major helminth parasites of public health importance in proboscis monkeys in BNP.

METHODS

A total of 65 faecal samples screened for helminth parasites via sodium nitrate floatation and faecal sedimentation techniques.

RESULTS

A total of 14 helminth parasite species comprising of eight genera of nematodes, two species of cestodes and two trematodes were identified. Eggs of Trichuris trichiura were the most frequently encountered in proboscis monkeys.

CONCLUSION

This is the first survey on the fauna of helminth parasites of proboscis monkeys living in mangrove forests, and therefore, it implies the important baseline information that increases our current knowledge for future research regarding parasite-host ecology in primates.

Topic modeling of major research themes in disease ecology of mammals

Disease ecology is a rapidly growing subdiscipline, and mammals and their parasites feature prominently in both historical and more recent research efforts. Nevertheless, the diversity of topics explored, and those not well explored, has not been systematically assessed. We conducted a systematic review of the published scientific literature in disease ecology of mammals and subjected the collection of original and review articles identified to a topic modeling approach, which is based on the words used in the published texts and their contexts (i.e., the frequency and strength of their semantic relationships with one another). In addition to concept maps identifying the most prominent research themes, we identified eight (not mutually exclusive) subcategories of studies, including experimental, theoretical, comparative, behavioral, immunological-microbiological, biogeographic-macroecological, vector-focused (e.g., mosquitoes), and disturbance-focused. The most prominent themes arising in review papers included the ecology of zoonotic diseases transmitted from non-human mammals, comparisons of pathogen prevalence between mammalian species, and pathogen discovery-disease surveillance studies, particularly of marine mammals and bats. For the original articles, the most prominent themes included ecology of rodent-transmitted viral and bacterial diseases and the population biology of zoonotic hosts. Most studies used comparative or descriptive approaches to investigate mammal-pathogen-disease relationships at a local scale, focusing on vector-borne diseases. Experimental, modeling, immunological, and behavioral approaches were strikingly underrepresented. Topics of strong conceptual importance, but that are underrepresented in the current literature, include: 1) the effects of the population density of mammalian hosts, and manipulations of density, on pathogen transmission; 2) macroecological studies that quantify effects of mammalian host species on parasite abundance and prevalence; and 3) effects of climate change on physiological and behavioral processes relevant to mammal-parasite interactions.

Bird cestodes from Huinay (Comau Fjord), Chilean Patagonia: several species of the family Dilepididae (Platyhelminthes, Cyclophyllidea), with the erection of two new genera

Birds in the Huinay area, Los Lagos region, Chile, were studied for parasites. Here we report 2 new genera and species of the family Dilepididae (Cyclophyllidea) found in common local passerines: Janinelliapeebeehigen. n., sp. n. was found in Elaeniaalbiceps (Tyrannidae) and Huinaylepiselegansgen. n., sp. n. was found in Aphrasturaspinicauda (Furnariidae). Other dilepidid parasites are reported for the first time from Xolmispyrope (Tyrannidae) and from 2 species of Rhinocryptidae. Cotylorhipissureshi Jadhav & Shinde, 1981 is considered a species inquirenda. The very high diversity and endemism of the observed cestode fauna in the Valdivian temperate rain forests is noted.

First Responders: Innate Immunity to Helminths

Helminth infections represent a significant public health concern resulting in devastating morbidity and economic consequences across the globe. Helminths migrate through mucosal sites causing tissue damage and the induction of type 2 immune responses. Antihelminth protection relies on the mobilization and activation of multiple immune cells, including type 2 innate lymphocytes (ILC2s), basophils, mast cells, macrophages, and hematopoietic stem/progenitor cells. Further, epithelial cells and neurons have been recognized as important regulators of type 2 immunity. Collectively, these pathways stimulate host-protective responses necessary for worm expulsion and the healing of affected tissues. In this review we focus on the innate immune pathways that regulate immunity to helminth parasites and describe how better understanding of these pathways may lead to the development of new therapeutic strategies.

Global spread of helminth parasites at the human-domestic animal-wildlife interface

Changes in species distributions open novel parasite transmission routes at the human-wildlife interface, yet the strength of biotic and biogeographical factors that prevent or facilitate parasite host shifting are not well understood. We investigated global patterns of helminth parasite (Nematoda, Cestoda, Trematoda) sharing between mammalian wildlife species and domestic mammal hosts (including humans) using >24,000 unique country-level records of host-parasite associations. We used hierarchical modelling and species trait data to determine possible drivers of the level of parasite sharing between wildlife species and either humans or domestic animal hosts. We found the diet of wildlife species to be a strong predictor of levels of helminth parasite sharing with humans and domestic animals, followed by a moderate effect of zoogeographical region and minor effects of species' habitat and climatic niches. Combining model predictions with the distribution and ecological profile data of wildlife species, we projected global risk maps that uncovered strikingly similar patterns of wildlife parasite sharing across geographical areas for the different domestic host species (including humans). These similarities are largely explained by the fact that widespread parasites are commonly recorded infecting several domestic species. If the dietary profile and position in the trophic chain of a wildlife species largely drives its level of helminth parasite sharing with humans/domestic animals, future range shifts of host species that result in novel trophic interactions may likely increase parasite host shifting and have important ramifications for human and animal health.

Comparison of The Endoparasite Fauna of Hoplias Malabaricus and Hoplerythrinus Unitaeniatus (Erythrinidae), Sympatric Hosts in the Eastern Amazon Region (Brazil)

Hoplias malabaricus and Hoplerythrinus unitaeniatus are Erythrinidae family widely distributed in the Amazon River system of great value to both commercial and subsistence fishing for riverine populations. As such, the objective of the present study was to investigate the endoparasite communities of H. malabaricus and H. unitaeniatus of a tributary of the Amazon River in the north of Brazil. The endoparasite communities of H. unitaeniatus and H. malabaricus were taxonomically similar (85%) and consisted of Clinostomum marginatum, Contracaecum sp., Guyanema seriei seriei, Procamallanus (Spirocamallanus) inopinatus, Pseudoproleptus sp. and Gorytocephalus spectabilis, although the dominant endoparasite was C. marginatum, which was the most prevalent and abundant. All the specimens of both H. malabaricus and H. unitaeniatus were parasitized, with a total of 1237 helminths collected in the former host and 1151 helminths collected in the latter. Hoplerythrinus unitaeniatus possessed greater parasite species richness. Both hosts had an aggregate dispersion of parasites, and the abundance of C. marginatum, Contracaecum sp. and G. spectabilis correlated positively with the weight and length of the hosts. The condition factor was not affected by parasitism, but the abundance of C. marginatum and Contracaecum sp. increased when the condition factor of the hosts decreased. This is the first report of G. seriei seriei for H. malabaricus and Pseudoproleptus sp. for H. unitaeniatus.

Some nematodes from freshwater fishes in central Africa

Twenty species (sixteen adult and four larval) of parasitic nematodes belonging to the Ascaridoidea, Camallanoidea, Cosmocercoidea, Dioctophymatoidea, Habronematoidea, Oxyuroidea, Seuratoidea, and Thelazioidea were collected from freshwater fishes of the Congo River basin in the Democratic Republic of the Congo and the Central African Republic in 2008 and 2012, respectively. Based on light and scanning electron microscopical examination, many species are redescribed in detail. This material also contained four previously unknown species, Labeonema longispiculatum sp. n. from Synodontis acanthomias Boulenger, Gendria longispiculata sp. n. from Schilbe grenfelli (Boulenger), G. sanghaensis sp. n. from Schilbe marmoratus Boulenger, and Cucullanus congolensis sp. n. from Auchenoglanis occidentalis (Valenciennes). The new species L. longispiculatum is mainly characterised by conspicuously long (210-228 µm) spicules, approximately twice as long as those in other congeners, the length (45-48 µm) of the gubernaculum and the host family (Mochokidae), whereas G. longispiculata by very long (1.2 mm) spicules, the shape of the oesophagus and cephalic vesicle, distribution of postanal papillae and the host family (Schilbeidae). Main characteristic features of G. sanghaensis are the presence of a hexagonal oral aperture surrounded by lip-like structures, the posterior portion of the oesophagus moderately expanded, spicules and the gubernaculum 414-438 µm and 54-57 µm long, respectively, deirids located at the level of the posterior end of the oesophagus and the absence of cervical alae. Cucullanus congolensis differs from congeneric species parasitising African freshwater and brackish-water fishes mainly in the absence of a ventral precloacal sucker and lateral preanal papillae, the presence of a large median precloacal papilla-like formation, spicules 480-489 µm long and the location of the excretory pore in the region of the oesophago-intestinal junction. Chabaudus Inglis et Ogden, 1965 is considered a junior synonym of Gendria Baylis, 1930 and, consequently, species listed in the former genus are transferred to the latter as G. alaini (Alfonso-Roque, 1981) comb. n., G. chabaudi (Inglis et Ogden, 1965) comb. n., G. dehradunensis (Rizvi, Bursey et Maity, 2016) comb. n., G. thysi (Puylaert, 1970) comb. n. and G. williamsi (Puylaert, 1970) comb. n. The findings represent many new host and geographical records.

Novel Therapeutics for Multiple Sclerosis Designed by Parasitic Worms

The evolutionary response to endemic infections with parasitic worms (helminth) was the development of a distinct regulatory immune profile arising from the need to encapsulate the helminths while simultaneously repairing tissue damage. According to the old friend's hypothesis, the diminished exposure to these parasites in the developed world has resulted in a dysregulated immune response that contributes to the increased incidence of immune mediated diseases such as Multiple Sclerosis (MS). Indeed, the global distribution of MS shows an inverse correlation to the prevalence of helminth infection. On this basis, the possibility of treating MS with helminth infection has been explored in animal models and phase 1 and 2 human clinical trials. However, the possibility also exists that the individual immune modulatory molecules secreted by helminth parasites may offer a more defined therapeutic strategy.

Some nematodes, including two new species, from freshwater fishes in the Sudan and Ethiopia

Fourteen species (twelve adult and two larval) of nematodes belonging to the Ascaridoidea, Camallanoidea, Cosmocercoidea, Habronematoidea, Oxyuroidea, Seuratoidea and Trichinelloidea were collected from fishes in the Sudan (River Nile and Atbara Dam Lake), whereas only four species (one adult and three larval) of the Ascaridoidea, Camallanoidea, Dioctophymatoidea and Trichinelloideafrom fishes in Ethiopia (Lake Tana). The Sudanese material also contained two previously unknown species, Cucullanus mormyri sp. n. from Mormyrus caschive Linnaeus (type host), Mormyrus sp. and Marcusenius cyprinoides (Linnaeus) (all Mormyridae), and Procamallanus (Spirocamallanus) pseudospiralis sp. n. from Synodontis schall (Bloch et Schneider) (type host), S. frontosus Vaillant and S. nigrita Valenciennes (all Mochokidae), which are described based on light and scanning electron microscopical studies. Cucullanus baylisi Campana-Rouget, 1961, a little-known parasite of Synodontis spp., is redescribed in detail. A key to Procamallanus (Spirocamallanus) spp. from African inland fishes is provided. Falcaustra guiersi Vassiliadès, 1973 is considered a junior synonym of F. hexapapillata (Khalil, 1962). The findings represent several new host and geographical records. Cucullanus baylisi Lakshmi, 2000 (= a homonym to C. baylisi Campana-Rouget, 1961) is re-named as C. dubius nom. n. and is considered a species inquirenda.

Are parasite richness and abundance linked to prey species richness and individual feeding preferences in fish hosts?

Variations in levels of parasitism among individuals in a population of hosts underpin the importance of parasites as an evolutionary or ecological force. Factors influencing parasite richness (number of parasite species) and load (abundance and biomass) at the individual host level ultimately form the basis of parasite infection patterns. In fish, diet range (number of prey taxa consumed) and prey selectivity (proportion of a particular prey taxon in the diet) have been shown to influence parasite infection levels. However, fish diet is most often characterized at the species or fish population level, thus ignoring variation among conspecific individuals and its potential effects on infection patterns among individuals. Here, we examined parasite infections and stomach contents of New Zealand freshwater fish at the individual level. We tested for potential links between the richness, abundance and biomass of helminth parasites and the diet range and prey selectivity of individual fish hosts. There was no obvious link between individual fish host diet and helminth infection levels. Our results were consistent across multiple fish host and parasite species and contrast with those of earlier studies in which fish diet and parasite infection were linked, hinting at a true disconnect between host diet and measures of parasite infections in our study systems. This absence of relationship between host diet and infection levels may be due to the relatively low richness of freshwater helminth parasites in New Zealand and high host-parasite specificity.

Why does infection with some helminths cause cancer?

Infections with Opisthorchis viverrini, Clonorchis sinensis and Schistosoma haematobium are classified as Group 1 biological carcinogens: definitive causes of cancer. These worms are metazoan eukaryotes, unlike the other Group 1 carcinogens including human papilloma virus, hepatitis C virus, and Helicobacter pylori. By contrast, infections with phylogenetic relatives of these helminths, also trematodes of the phylum Platyhelminthes and major human pathogens, are not carcinogenic. These inconsistencies prompt several questions, including how might these infections cause cancer? And why is infection with only a few helminth species carcinogenic? Here we present an interpretation of mechanisms contributing to the carcinogenicity of these helminth infections, including roles for catechol estrogen- and oxysterol-metabolites of parasite origin as initiators of carcinogenesis.

Measuring fish body condition with or without parasites: does it matter?

A fish body condition index was calculated twice for each individual fish, including or excluding parasite mass from fish body mass, and index values were compared to test the effects of parasite mass on measurement of body condition. Potential correlations between parasite load and the two alternative fish condition index values were tested to assess how parasite mass may influence the perception of the actual effects of parasitism on fish body condition. Helminth parasite mass was estimated in common bully Gobiomorphus cotidianus from four New Zealand lakes and used to assess the biasing effects of parasite mass on body condition indices. Results showed that the inclusion or exclusion of parasite mass from fish body mass in index calculations significantly influenced correlation patterns between parasite load and fish body condition indices. When parasite mass was included, there was a positive correlation between parasite load and fish body condition, seemingly indicating that fish in better condition supported higher parasite loads. When parasite mass was excluded, there was no correlation between parasite load and fish body condition, i.e. there was no detectable effect of helminth parasites on fish condition or fish condition on parasite load. Fish body condition tended to be overestimated when parasite mass was not accounted for; results showed a positive correlation between relative parasite mass and the degree to which individual fish condition was overestimated. Regardless of the actual effects of helminth parasites on fish condition, parasite mass contained within a fish should be taken into account when estimating fish condition. Parasite tissues are not host tissues and should not be included in fish mass when calculating a body condition index, especially when looking at potential effects of helminth infections on fish condition.

Studies on ascaridid, oxyurid and enoplid nematodes (Nematoda) from fishes of the Okavango River, Botswana

Based on light and scanning electron microscopical studies, eight species (five adult and three larval) of nematodes belonging to the Ascaridida, Oxyurida and Enoplida were collected from fishes of the Okavango River, Botswana, namely Falcaustra similis Moravec et Van As, 2004, Atractidae gen. sp. (only female) (both Cosmocercoidea), Cucullanus sp. (only female) (Seuratoidea), Cithariniella longicaudata sp. n., Synodontisia annulata sp. n. (both Oxyuroidea), Contracaecum sp. third-stage larvae, third-stage larvae of Galeiceps sp. (both Ascaridoidea) and Eustrongylides sp. fourth-stage larvae (Dioctophymatoidea). The new species Citharinella longicaudata (type host Schilbe intermedius Rüppel) is mainly characterised by the shape and size of cephalic papillae and the spicule 108 µm long, and Synodontisia annulata (type host S. intermedius) by the shape of cephalic papillae, body length of gravid females (4.88-5.33 mm) and a short spicule (66 µm long). The female specimen of Cucullanus sp. from Tilapia sparmanni Smith markedly differs from congeners parasitising inland fishes in Africa by the elongate pseudobuccal capsule and by the excretory pore far posterior to the oesophago-intestinal junction; apparently, it belongs to an undescribed species. Galeiceps larvae parasitising fishes are described for the first time. Cithariniella gonzalezi Van Waerebeke, Chabaud, Bain et Georges, 1988 is considered a junior synonym of C. khalili Petter, Vassiliadès et Troncy, 1972, and the previous records of Cithariniella citharini Khalil, 1964 from Synodontis spp. in Egypt concern, in fact, Cithariniella khalili Petter, Vassiliadès et Troncy, 1972. The specimens of Cithariniella reported by Koubková et al. (2010) from Paradistichodus dimidiatus (Pellegrin) in Senegal and misidentified as C. gonzalesi Van Waerebeke, Chabaud, Bain et Georges, 1988 are considered to represent a new species, C. koubkovae sp. n.; this is established by reference to the description and drawings provided by Koubková et al. (2010).

Plants as de-worming agents of livestock in the Nordic countries: historical perspective, popular beliefs and prospects for the future

Preparations derived from plants were the original therapeutic interventions used by man to control diseases (including parasites), both within humans and livestock. Development of herbal products depended upon local botanical flora with the result that different remedies tended to develop in different parts of the world. Nevertheless, in some instances, the same or related plants were used over wide geographic regions, which also was the result of communication and/or the importation of plant material of high repute. Thus, the Nordic countries have an ancient, rich and diverse history of plant derived anthelmintic medications for human and animal use. Although some of the more commonly used herbal de-wormers were derived from imported plants, or their products, many are from endemic plants or those that thrive in the Scandinavian environment. With the advent of the modern chemotherapeutic era, and the discovery, development and marketing of a seemingly unlimited variety of highly efficacious, safe synthetic chemicals with very wide spectra of activities, herbal remedies virtually disappeared from the consciousness--at least in the Western world. This attitude is now rapidly changing. There is a widespread resurgence in natural product medication, driven by major threats posed by multi-resistant pest, or disease, organisms and the diminishing public perceptions that synthetic chemicals are the panacea to health and disease control. This review attempts to provide a comprehensive account of the depth of historical Nordic information available on herbal de-wormers, with emphasis on livestock and to provide some insights on potentially rewarding areas of "re-discovery" and scientific evaluation in this field.

Inhibition of hepatitis B virus replication during schistosoma mansoni infection in transgenic mice

Although coinfection of hepatitis B virus (HBV) and Schistosoma mansoni is a frequent event in humans, little is known about the interactions between these two pathogens. S. mansoni infection induces T helper cell type 2 (Th2)-type cytokines in the liver of humans and mice. The intrahepatic induction of nitric oxide (NO) and Th1-type cytokines, such as interferon (IFN)-gamma and IFN-alpha/beta, inhibits HBV replication noncytopathically in the liver of transgenic mice. To examine whether S. mansoni infection and the accompanying induction of Th2-type cytokines could interfere with HBV replication in the liver, HBV transgenic mice were infected with S. mansoni. By 5 wk after infection, HBV replication disappeared concomitant with the intrahepatic induction of NO and Th1-type cytokines, and in the absence of Th2-type cytokines. By 6-8 wk after infection, HBV replication remained undetectable and this was associated with further induction of NO and Th1-type cytokines together with the appearance of Th2-type cytokines. The S. mansoni-dependent antiviral effect was partially blocked by genetically deleting IFN-gamma, although it was unaffected by deletion of IFN-alpha/beta. These results indicate that IFN-gamma (probably via NO) mediates most of this antiviral activity and that Th2-type cytokines do not counteract the antiviral effect of IFN-gamma. Similar events may suppress HBV replication during human S. mansoni infection.

Major histocompatibility complex variation associated with juvenile survival and parasite resistance in a large unmanaged ungulate population

Antagonistic coevolution between hosts and parasites has been proposed as a mechanism maintaining genetic diversity in both host and parasite populations. In particular, the high levels of genetic diversity widely observed at the major histocompatibility complex (MHC) of vertebrate hosts are consistent with the hypothesis of parasite-driven balancing selection acting to maintain MHC genetic diversity. To date, however, empirical evidence in support of this hypothesis, especially from natural populations, has been lacking. A large unmanaged population of Soay sheep (Ovis aries L.) is used to investigate associations between MHC variation, juvenile survival, and parasite resistance. We show in an unmanaged, nonhuman population that allelic variation within the MHC is significantly associated with differences in both juvenile survival and resistance to intestinal nematodes. Certain MHC alleles are associated with low survivorship probabilities and high levels of parasitism or vice versa. We conclude that parasites are likely to play a major role in the maintenance of MHC diversity in this population.