Are Ascaris lumbricoides and Ascaris suum a single species?

Acute Ascaris infection impairs the effector functions of natural killer cells in single and Salmonella co-infected pigs

Natural killer (NK) cells play a key role in defense against Salmonella infections during the early phase of infection. Our previous work showed that the excretory/secretory products of Ascaris suum repressed NK activity in vitro. Here, we asked if NK cell functionality was influenced in domestic pigs during coinfection with Ascaris and Salmonella enterica serotype Typhimurium. Ascaris coinfection completely abolished the IL-12 and IL-18 driven elevation of IFN-γ production seen in CD16 + CD8α + perforin + NK cells of Salmonella single-infected pigs. Furthermore, Ascaris coinfection prohibited the Salmonella-driven rise in NK perforin levels and CD107a surface expression. In line with impaired effector functions, NK cells from Ascaris-single and coinfected pigs displayed elevated expression of the inhibitory KLRA1 and NKG2A receptors genes, contrasting with the higher expression of the activating NKp46 and NKp30 receptors in NK cells during Salmonella single infection. These differences were accompanied by the highly significant upregulation of T-bet protein expression in NK cells from Ascaris-single and Ascaris/Salmonella coinfected pigs. Together, our data strongly indicate a profound repression of NK functionality by an Ascaris infection which may hinder infected individuals from adequately responding to a concurrent bacterial infection.

Evaluation of copromicroscopy, multiplex-qPCR and antibody serology for monitoring of human ascariasis in endemic settings

BACKGROUND

The standard diagnosis of Ascaris lumbricoides and other soil-transmitted helminth (STH) infections relies on the detection of worm eggs by copromicroscopy. However, this method is dependent on worm patency and shows only limited accuracy in low-intensity infection settings. We aimed to decipher the diagnostic accuracy of different antibodies using various Ascaris antigens in reference to copromicroscopy and quantitative PCR (qPCR), four months after national STH preventative chemotherapy among school children in western Kenya.

METHODOLOGY

STH infection status of 390 school children was evaluated via copromicroscopy (Kato-Katz and mini-FLOTAC) and qPCR. In parallel, Ascaris-specific antibody profiles against larval and adult worm lysates, and adult worm excretory-secretory (ES) products were determined by enzyme-linked immunosorbent assay. Antibody cross-reactivity was evaluated using the closely related zoonotic roundworm species Toxocara cati and Toxocara canis. The diagnostic accuracy of each antibody was evaluated using receiver operating curve analysis and the correspondent area under the curve (AUC).

PRINCIPAL FINDINGS

Ascaris was the predominant helminth infection with an overall prevalence of 14.9% (58/390). The sensitivity of mini-FLOTAC and Kato-Katz for Ascaris diagnosis reached only 53.5% and 63.8%, respectively compared to qPCR. Although being more sensitive, qPCR values correlated with microscopic egg counts (R = -0.71, P<0.001), in contrast to antibody levels. Strikingly, IgG antibodies recognizing the ES products of adult Ascaris worms reliably diagnosed active Ascaris infection as determined by qPCR and microscopy, with IgG1 displaying the highest accuracy (AUC = 0.83, 95% CI: 0.75-0.91).

CONCLUSION

IgG1 antibody responses against adult Ascaris-ES products hold a promising potential for complementing the standard fecal and molecular techniques employed for monitoring Ascaris infections. This is of particular importance in the context of deworming programs as the antibody diagnostic accuracy was independent of egg counts.

Worldwide absence of canonical benzimidazole resistance-associated mutations within β-tubulin genes from Ascaris

BACKGROUND

The giant roundworm Ascaris is an intestinal nematode, causing ascariasis by infecting humans and pigs worldwide. Recent estimates suggest that Ascaris infects over half a billion people, with chronic infections leading to reduced growth and cognitive ability. Ascariasis affects innumerable pigs worldwide and is known to reduce production yields via decreased growth and condemnation of livers. The predominant anthelminthic drugs used to treat ascariasis are the benzimidazoles. Benzimidazoles interact with β-tubulins and block their function, and several benzimidazole resistance-associated mutations have been described in the β-tubulins of ruminant nematodes. Recent research on ascarids has shown that these canonical benzimidazole resistance-associated mutations are likely not present in the β-tubulins of Ascaris, Ascaridia or Parascaris, even in phenotypically resistant populations.

METHODS

To further determine the putative absence of key β-tubulin polymorphisms, we screened two β-tubulin isotypes of Ascaris, highly expressed in adult worms. Using adult and egg samples of Ascaris obtained from pigs and humans worldwide, we performed deep amplicon sequencing to look for canonical resistance-associated mutations in Ascaris β-tubulins. Subsequently, we examined these data in closer detail to study the population dynamics of Ascaris and genetic diversity within the two isotypes and tested whether genotypes appeared to partition across human and pig hosts.

RESULTS

In the 187 isolates, 69 genotypes were found, made up of eight haplotypes of β-tubulin isotype A and 20 haplotypes of isotype B. Single nucleotide polymorphisms were seen at 14 and 37 positions for β-tubulin isotype A and isotype B, respectively. No evidence of any canonical benzimidazole resistance-associated mutations was found in either human- or pig-derived Ascaris isolates. There was, however, a difference in the genetic diversity of each isotype and distribution of β-tubulin genotypes between human- and pig-derived Ascaris. Statistical tests of population differentiation show significant differences (p < 0.001) between pig- and human-derived worms; however, more diversity was seen between worms from different populations than worms from different hosts.

CONCLUSIONS

Our work suggests an absence of canonical β-tubulin mutations within Ascaris, but alternative modes of anthelminthic resistance may emerge necessitating continued genetic scrutiny alongside monitoring of drug efficacy.

Ascaris suum infection in juvenile pigs elicits a local Th2 response in a setting of ongoing Th1 expansion

Ascaris spp. undergo extensive migration within the body before establishing patent infections in the small intestinal tract of humans and pigs. However, whether larval migration is critical for inducing efficient type 2 responses remains poorly understood. Therefore, we investigated systemic versus local adaptive immune responses along the hepato-tracheal migration of Ascaris suum during primary, single infections in conventionally raised pigs. Neither the initial invasion of gut tissue nor migration through the liver resulted in discernable Th2 cell responses. In contrast, lung-stage larvae elicited a Th2-biased pulmonary response, which declined after the larvae had left the lungs. In the small intestine, we observed an accumulation of Th2 cells upon the arrival of fourth-stage larvae (L4) to the small intestinal lumen. In parallel, we noticed robust and increasing Th1 responses in circulation, migration-affected organs, and draining lymph nodes. Phenotypic analysis of CD4+ T cells specifically recognizing A. suum antigens in the circulation and lung tissue of infected pigs confirmed that the majority of Ascaris-specific T cells produced IL-4 (Th2) and, to a much lesser extent, IL-4/IFN-g (Th2/1 hybrids) or IFN-g alone (Th1). These data demonstrate that lung-stage but not the early liver-stage larvae lead to a locally restricted Th2 response. Significant Th2 cell accumulation in the small intestine occurs only when L4 complete the body migration. In addition, Th2 immunity seems to be hampered by the concurrent, nonspecific Th1 bias in growing pigs. Together, the late onset of Th2 immunity at the site of infection and the Th1-biased systemic immunity likely enable the establishment of intestinal infections by sufficiently large L4 stages and pre-adult worms, some of which resist expulsion mechanisms.

The nematode (Ascaris suum) intestine is a location of synergistic anthelmintic effects of Cry5B and levamisole

A novel group of biocidal compounds are the Crystal 3D (Cry) and Cytolytic (Cyt) proteins produced by Bacillus thuringiensis (Bt). Some Bt Cry proteins have a selective nematocidal activity, with Cry5B being the most studied. Cry5B kills nematode parasites by binding selectively to membrane glycosphingolipids, then forming pores in the cell membranes of the intestine leading to damage. Cry5B selectively targets multiple species of nematodes from different clades and has no effect against mammalian hosts. Levamisole is a cholinergic anthelmintic that acts by selectively opening L-subtype nicotinic acetylcholine receptor ion-channels (L-AChRs) that have been found on muscles of nematodes. A synergistic nematocidal interaction between levamisole and Cry5B at the whole-worm level has been described previously, but the location, mechanism and time-course of this synergism is not known. In this study we follow the timeline of the effects of levamisole and Cry5B on the Ca2+ levels in enterocyte cells in the intestine of Ascaris suum using fluorescence imaging. The peak Ca2+ responses to levamisole were observed after approximately 10 minutes while the peak responses to activated Cry5B were observed after approximately 80 minutes. When levamisole and Cry5B were applied simultaneously, we observed that the responses to Cry5B were bigger and occurred sooner than when it was applied by itself. It is proposed that the synergism is due to the cytoplasmic Ca2+ overload that is induced by the combination of levamisole opening Ca2+ permeable L-subtype nAChRs and the Ca2+ permeable Cry5B toxin pores produced in the enterocyte plasma membranes. The effect of levamisole potentiates and speeds the actions of Cry5B that gives rise to bigger Ca2+ overloads that accelerates cell-death of the enterocytes.

A Comparison of the Prevalence of Gastrointestinal Parasites in Wild Boar (Sus scrofa L.) Foraging in Urban and Suburban Areas

The aim of this study was to compare the species composition of gastrointestinal parasites in wild boar feeding in the city of Szczecin with those in its suburban area, as well as to determine the prevalence and intensity of this parasite infection. The intestines and stomachs of 57 wild boars were supplied by a municipal hunter from the city of Szczecin. Both analysed groups of animals were infected with the following parasites: Eimeria debliecki, E. suis, E. polita, E. scabra, Isospora suis, Ascaris suum and Oesophagostomum dentatum. Wild boar from the city were characterised as having a significantly higher prevalence of total Eimeria (p = 0.04) and a lower prevalence of noted species of nematodes (p = 0.15) compared to those from the suburban area. Since the wild boars were mainly infected with Eimeria, it should be assumed that they may pose a real health threat to farm pigs and other farm animals for which Eimeria is a pathogenic parasite. The occurrence of coccidiosis leads to serious health problems and economic losses for breeders. Although the prevalence of A. suum was low, it should be taken into account that this nematode is able to both infect and complete their life cycle in humans.

Is strongyloidiasis a zoonosis from dogs?

Strongyloides stercoralis infection remains a major veterinary and public health challenge globally. This chronic and potentially lifelong disease has fatal outcomes in immunosuppressed people and dogs. Currently, the role of dogs in the transmission cycle of human strongyloidiasis remains enigmatic. While zoonotic transmission to humans from companion animals has been proposed, this has not been confirmed. Modern molecular methods have allowed greater opportunity to explore the genotypes of S. stercoralis in dogs and humans. Work thus far has demonstrated that at least two distinct lineages exist, one apparently confined to canine hosts and one found in canine, feline, human and non-human primate hosts. Although genotyping of dog and human isolates from the same village has demonstrated identical genotypes in both species, coprophagia of human waste by dogs confounds interpretation. It remains unclear if dogs act as a zoonotic reservoir for human infection, or vice versa, or if this occurs only in some regions of the world and not in others. These questions must be answered before effective control strategies for strongyloidiasis can be instituted. This review explores the evidence for and against cross-species transmission of S. stercoralis between dogs and humans and summarizes future directions for research in this area. This article is part of the Theo Murphy meeting Issue 'Strongyloides: omics to worm-free populations'.

Effect of Selected Entomopathogenic Fungal Species on Embryonic Development of Ascaris suum (Nematoda)

The aim of the study was to evaluate the potential of using five selected species of entomopathogenic fungi (Beauveria bassiana, B. brongniartii, Conidiobolus coronatus, Isaria fumosorosea, and Metarhizium robertsii) in the bioregulation of the dispersive stages of the parasitic nematode-Ascaris suum. Experimental cultures of each of the selected entomopathogenic fungi, as well as a control culture without fungi, were incubated with A. suum eggs at 26 °C for 28 days. Development of the A. suum eggs was observed using a light microscope on the 7th, 14th, 21st, and 28th days of incubation. The API-ZYM® test was used to determine, semiquantitatively, the activity of 19 hydrolytic enzymes from the entomopathogenic fungi. The cytotoxicity of the fungi was determined using tetrazole salt MTT. It was found that none of the five tested strains of entomopathogenic fungi showed an ovicidal effect, and none of them colonized the A. suum egg shells. However, ovistatic activity was observed mainly until the 14th day of incubation by I. fumosorosea, M. robertsii, and B. bassiana. In the MTT test, M. robertsii showed moderate cytotoxicity, while the other species showed low cytotoxicity. Among the strains tested, I. fumosorosea showed the highest spectrum of hydrolase production (13 out of 19 enzymes gave a positive reaction from 3 to 5; 20-40 nM or more). The absence of morphological changes in the A. suum egg shells suggests that the antagonistic effect of the studied entomopathogenic fungi may be due to their cytotoxicity, associated with the production of secondary metabolites-toxins (M. robertsii) and enzymatic activity (I. fumosorosea).

Implications of the prevalence of Ascaris sp. in the funerary context of a Late Antique population (5th-7th c.) in Granada (Spain)

OBJECTIVE

To evaluate the prevalence of gastro-intestinal parasites in human remains from Late Antiquity (5th - 7th c.) Granada (Spain).

MATERIALS

The study included pelvic and cranial control samples from 17 skeletons from the archaeological sites of Los Mondragones (n = 13) and Rafael Guillén (n = 4).

METHODS

In the paleoparasitological study, soil samples from pelvic area and cranium were analyzed using the rehydration, homogenization, and micro-sieving method and visualization under brightfield microscopy.

RESULTS

Ascaris sp. eggs were detected in pelvic samples from seven individuals.

CONCLUSIONS

These findings may indicate that this parasite was endemic. Its detection frequency is one of the highest reported at group level in an osteological series from Late Antiquity.

SIGNIFICANCE

The prevalence of Ascaris sp. associated with skeletal remains has implications for assessing the lifestyle and health of populations in southern Spain during the Late Antique period.

LIMITATIONS

The number of individuals is small and taphonomic processes could have limited paleoparasitological findings SUGGESTIONS FOR FURTHER RESEARCH: Future interdisciplinary studies of this type are warranted in larger osteological series to improve knowledge of parasitosis in the past.

The nematode (Ascaris suum) intestine is a location of synergistic anthelmintic effects of Cry5B and levamisole

A novel group of biocidal compounds are the Crystal 3D (Cry) and Cytolytic (Cyt) proteins produced by Bacillus thuringiensis (Bt). Some Bt Cry proteins have a selective nematocidal activity, with Cry5B being the most studied. Cry5B kills nematode parasites by binding selectively to membrane glycosphingolipids, then forming pores in the cell membranes of the intestine leading to damage. Cry5B selectively targets multiple species of nematodes from different clades and has no effect against mammalian hosts. Levamisole is a cholinomimetic anthelmintic that acts by selectively opening L-subtype nicotinic acetylcholine receptor ion-channels (L-AChRs) that have been found on muscles of nematodes. A synergistic nematocidal interaction between levamisole and Cry5B has been described previously, but the location, mechanism and time-course of this synergism is not known. In this study we follow the timeline of the effects of levamisole and Cry5B on the Ca2+ levels in enterocyte cells from the intestine of Ascaris suum using fluorescence imaging. The peak Ca2+ responses to levamisole were observed after approximately 10 minutes while the peak responses to activated Cry5B were observed after approximately 80 minutes. When levamisole and Cry5B were applied simultaneously, we observed that the responses to Cry5B were bigger and occurred sooner than when it was applied by itself. It is proposed that there is an irreversible cytoplasmic Ca2+ overload that leads to necrotic cell-death in the enterocyte that is induced by levamisole opening Ca2+ permeable L-subtype nAChRs and the development of Ca2+ permeable Cry5B toxin pores in enterocyte plasma membranes. The effects of levamisole potentiate and speed the actions of Cry5B.

Paleoparasitology research on ancient helminth eggs and larvae in the Republic of Korea

Paleoparasitology is a discipline that applies existing conventional and molecular techniques to study parasites found in ancient ruins. This review focuses on the history of the discovery of parasites (mostly helminth eggs and larvae) in archaeological soil samples and mummies in Korea from the Three Kingdoms Period to the Joseon Dynasty (100 BCE-1910 CE). We also briefly review important milestones in global paleoparasitology. The helminth species reported so far in Korea included Ascaris lumbricoides, Trichuris trichiura, Strongyloides stercoralis (larva), Trichostrongylus sp. (larva), Paracapillaria philippinensis (syn. Capillaria philippinensis), Enterobius vermicularis, Fasciola hepatica, dicrocoeliids, Paragonimus westermani, Clonorchis sinensis, Metagonimus yokogawai, Pygidiopsis summa, Gymnophalloides seoi, Isthmiophora hortensis, Dibothriocephalus nihonkaiensis (syn. Diphyllobothrium nihonkaiense), and Taenia spp. tapeworms. The findings obtained by Korean paleoparasitologists/archaeologists have brought about deep insight into the status of helminthic infections in Korea's past populations. Continued paleoparasitological research is essential for further understanding of ancient parasites and parasitic diseases in Korea.

A molecular and morphological study of Ascaris suum in a human-pig contact scenario in northeastern Brazil

The aim of the present study was to assess morphologic and genetic data on ascariasis in swine (Sus scrofa domesticus) and humans in low-resource rural and periurban communities in the state of Piauí, Brazil. Our cross-sectional survey included 100 fecal samples obtained from swine and 682 samples from humans. Fifteen pigs were necropsied. Human and porcine fecal samples were examined to identify Ascaris eggs. Parasites obtained in the swine necropsies were studied using scanning electron microscopy (SEM), and the mitochondrial gene encoding the cytochrome oxidase 1 (cox1) enzyme was partially amplified and sequenced for molecular taxonomy and phylogenetic analyses. The overall prevalence of Ascaris eggs in the swine fecal samples was 16/100 (16%). No Ascaris eggs were identified in the human fecal samples. SEM of six worms recovered from pigs demonstrated morphological characteristics of A. suum. Cox1 sequences were compatible with A. suum reference sequences. Original and reference (GenBank) nucleotide sequences were organized into clusters that did not segregate the parasites by host species or and region. The largest haplogroups were dominated by haplotypes H01, H02 and H31. In the communities studied, there was no epidemiological evidence of the zoonotic transmission of ascariasis at the human-swine interface.

First molecular data on the human roundworm Ascaris lumbricoides species complex from the Bronze and Iron Age in Hallstatt, Austria

Palaeoparasitological studies can provide valuable information on the emergence, distribution, and elimination of parasites during a particular time in the past. In the prehistoric salt mines of Hallstatt, located in the Austrian Alps, human faeces have been conserved in salt. The aim of this study was to recover ancient DNA of intestinal parasites from these coprolites. Altogether, 35 coprolites from the Hallstatt salt mines, dating back to the Bronze Age mining phase (1158-1063 BCE) and the Iron Age mining phase (750-662 BCE), respectively, were analysed by microscopy and molecular methods. In 91% of the coprolite samples, eggs of soil-transmitted helminths (STH), namely of Trichuris and/or Ascaris were detected by light microscopy. The Ascaris eggs were exceptionally well preserved. For further analysis, DNA was extracted from the palaeofaecal samples and species-specific primers targeting different genes were designed. While amplification of Trichuris DNA remained unsuccessful, sequence data of A. lumbricoides species complex were successfully obtained from 16 coprolites from three different genes, the mitochondrial cytochrome c oxidase subunit 1 gene (cox1), the mitochondrial cytochrome B gene (cytB) and the mitochondrial NADH dehydrogenase subunit 1 gene (nadh1). Importantly, these included two Ascaris sequences from a coprolite from the Bronze Age, which to the best of our knowledge are the first molecular data of this genus from this period.

The turkey ascarid, Ascaridia dissimilis, as a model genetic system

Parasitic nematodes cause significant effects on humans each year, with the most prevalent being Ascaris lumbricoides. Benzimidazoles (BZ) are the most widely used anthelmintic drug in humans, and although the biology of resistance to this drug class is understood in some species, resistance is poorly characterized in ascarids. Models such as Caenorhabditis elegans were essential in developing our current understanding of BZ resistance, but more closely related model nematodes are needed to understand resistance in ascarids. Here, we propose a new ascarid model species that infects turkeys, Ascaridia dissimilis, to develop a better understanding of BZ resistance.

First Study of Ascaris lumbricoides from the Semiwild Population of the Sumatran Orangutan Pongo abelii in the Context of Morphological Description and Molecular Phylogeny

There is little evidence that the already described and accepted taxa of ascarids (Ascaris lumbricoides, A. suum, and A. ovis) infecting individuals of taxonomically distant groups (hominids, pigs, sheep, goats, and dogs) can be genetically or morphologically distinguished. However, despite described morphological differences, e.g., due to intraspecific variation, these are insufficient for species determination and may indicate differences amongst ascarids because of cross infections, hybrid production, and specific adaptations to hosts. Herein, the results of a molecular and morphological analysis of ascarids parasitising Sumatran orangutans (Pongo abelii Lesson, 1827) in native populations are presented. The research took place in the Bukit Lawang area, Indonesia, in 2009. Throughout the year, fresh faecal samples were collected regularly from 24 orangutans, and all were examined for the presence of nematode adults. Only five adult worms from two orangutan females were found during regular collection. Using the integrative taxonomic approach, the nematodes found were identified as A. lumbricoides. The significance of the find and its rarity is documented by the fact that this is the first confirmed finding of adult ascarids from an original orangutan site (not from a zoo) in more than 130 years (including the long-term study spanning the last 20 years focusing on orangutan parasites and natural antiparasitic drugs). More accurate morphometric parameters and genetic differences for the identification of ascarids were established. These parameters will be helpful for other findings in great apes and will also be suitable for further and precise determination of this parasite. The details distinguishing between male and female specimens are also stated and well defined. A comprehensive evaluation of the situation of Ascaris species parasitising orangutans, including a comparison with previously described orangutan parasite (i.e., A. satyri-species inquirenda), is discussed.

Soil-transmitted helminthic vaccines: Where are we now?

It has been tested and proven that vaccination is still the best strategy to combat infectious diseases. However, to date, there are still no vaccines against human soil-transmitted helminthic diseases, despite their high prevalence globally, particularly in developing countries and rural areas with tropical climates and poor sanitation. The development of vaccines against helminths is riddled with obstacles. Helminths have a complex life cycle, multiple stages within the same host with stage-specific antigen expression, and the ability to regulate host immune reactions to evade the immune response. These elements contribute to the main challenge of helminthic vaccines: the identification of effective vaccine candidates. Therefore, this article reviews the current progress and potential future direction of soil-transmitted helminthic vaccines, particularly against Trichuris trichiura, Ascaris lumbricoides, Strongyloides stercoralis, Necator americanus and Ancylostoma duodenale. The study design employed was a systematic review, using qualitative meta-summary synthesis. Preclinical studies and clinical trials on the development of protein subunit vaccines against the five soil-transmitted helminths were searched on PubMed and Scopus. Effectiveness was indicated by a reduction in worm burden or larval output, an increase in specific IgG levels, or an increase in cytokine production. Our findings show that only the hookworm vaccine against N. americanus is in the clinical trial phase, while the rest is still in exploratory research and pre-clinical development phase.

Evaluation of genome skimming to detect and characterise human and livestock helminths

The identification of gastrointestinal helminth infections of humans and livestock almost exclusively relies on the detection of eggs or larvae in faeces, followed by manual counting and morphological characterisation to differentiate species using microscopy-based techniques. However, molecular approaches based on the detection and quantification of parasite DNA are becoming more prevalent, increasing the sensitivity, specificity and throughput of diagnostic assays. High-throughput sequencing, from single PCR targets through to the analysis of whole genomes, offers significant promise towards providing information-rich data that may add value beyond traditional and conventional molecular approaches; however, thus far, its utility has not been fully explored to detect helminths in faecal samples. In this study, low-depth whole genome sequencing, i.e. genome skimming, has been applied to detect and characterise helminth diversity in a set of helminth-infected human and livestock faecal material. The strengths and limitations of this approach are evaluated using three methods to characterise and differentiate metagenomic sequencing data based on (i) mapping to whole mitochondrial genomes, (ii) whole genome assemblies, and (iii) a comprehensive internal transcribed spacer 2 (ITS2) database, together with validation using quantitative PCR (qPCR). Our analyses suggest that genome skimming can successfully identify most single and multi-species infections reported by qPCR and can provide sufficient coverage within some samples to resolve consensus mitochondrial genomes, thus facilitating phylogenetic analyses of selected genera, e.g. Ascaris spp. Key to this approach is both the availability and integrity of helminth reference genomes, some of which are currently contaminated with bacterial and host sequences. The success of genome skimming of faecal DNA is dependent on the availability of vouchered sequences of helminths spanning both taxonomic and geographic diversity, together with methods to detect or amplify minute quantities of parasite nucleic acids in mixed samples.

Diethylcarbamazine, TRP channels and Ca2+ signaling in cells of the Ascaris intestine

The nematode parasite intestine absorbs nutrients, is involved in innate immunity, can metabolize xenobiotics and as we show here, is also a site of action of the anthelmintic, diethylcarbamazine. Diethylcarbamazine (DEC) is used to treat lymphatic filariasis and activates TRP-2, GON-2 & CED-11 TRP channels in Brugia malayi muscle cells producing spastic paralysis. DEC also has stimulatory effects on ascarid nematode parasites. Using PCR techniques, we detected, in Ascaris suum intestine, message for: Asu-trp-2, Asu-gon-2, Asu-ced-11, Asu-ocr-1, Asu-osm-9 and Asu-trpa-1. Comparison of amino-acid sequences of the TRP channels of B. malayi, and A. suum revealed noteworthy similarity, suggesting that the intestine of Ascaris will also be sensitive to DEC. We used Fluo-3AM as a Ca2+ indicator and observed characteristic unsteady time-dependent increases in the Ca2+ signal in the intestine in response to DEC. Application of La3+ and the TRP channel inhibitors, 2-APB or SKF 96365, inhibited DEC mediated increases in intracellular Ca2+. These observations are important because they emphasize that the nematode intestine, in addition to muscle, is a site of action of DEC as well as other anthelmintics. DEC may also enhance the Ca2+ toxicity effects of other anthelmintics acting on the intestine or, increase the effects of other anthelmintics that are metabolized and excreted by the nematode intestine.

Essential Oils as Novel Anthelmintic Drug Candidates

Helminths, with an estimated 1.5 billion annual global infections, are one of the major health challenges worldwide. The current strategy of the World Health Organization to prevent helminth infection includes increasing hygienic awareness, providing better sanitation and preventative anthelmintic drug therapy in vulnerable populations. Nowadays, anthelmintic drugs are used heavily in livestock, both in case of infection and as a preventative measure. However, this has led to the development of resistance against several of the most common drugs, such as levamisole, ivermectin and thiabendazole. As many as 70% of the livestock in developed countries now has helminths that are drug resistant, and multiple resistance is common. Because of this, novel anthelmintics are urgently needed to help combat large-scale production losses. Prior to this review, no comprehensive review of the anthelmintic effects of essential oils and their components existed. Multiple review articles have been published on the uses of a single plant and its extracts that only briefly touch upon their anthelmintic activity. This review aims to provide a detailed overview of essential oils and their components as anthelmintic treatment against a wider variety of helminths.

Ascaris suum excretory/secretory products differentially modulate porcine dendritic cell subsets

Helminths produce excretory/secretory products (E/S) which can modulate the immune responses of their hosts. Dendritic cells (DC) are essential for initiating the host T cell response and are thus potential targets for modulation by helminth E/S. Here we study immunomodulation of porcine peripheral blood DC subsets following ex vivo stimulation with E/S from Ascaris suum, a common helminth of pigs with considerable public health and economic importance. Our data showed that the relative frequencies of DC subsets in porcine blood differ, with plasmacytoid DC (pDC) being the most prominent in healthy 6-month-old pigs. pDC are an important cytokine source, and we found that A. suum E/S suppressed production of the type 1 cytokines IL-12p40 and TNF-α by this subset following toll-like receptor (TLR) ligation. In contrast, conventional DC (cDC) are more efficient antigen presenters, and the expression of CD80/86, costimulatory molecules essential for efficient antigen presentation, were modulated differentially by A. suum E/S between cDC subsets. CD80/86 expression by type 1 cDC (cDC1) following TLR ligation was greatly suppressed by the addition of A. suum E/S, while CD80/86 expression by type 2 cDC (cDC2) was upregulated by A. suum E/S. Further, we found that IFN-γ production by natural killer (NK) cells following IL-12 and IL-18 stimulation was suppressed by A. suum E/S. Finally, in the presence of E/S, IFN-γ production by CD4+ T cells co-cultured with autologous blood-derived DC was significantly impaired. Together, these data provide a coherent picture regarding the regulation of type 1 responses by A. suum E/S. Responsiveness of pDC and cDC1 to microbial ligands is reduced in the presence of E/S, effector functions of Th1 cells are impaired, and cytokine-driven IFN-γ release by NK cells is limited.

Effects of adult Ascaris suum and their antigens (total and trans-cuticular excretory-secretory antigen, cuticular somatic antigen) on intestinal nutrient transport in vivo

Ascaris suum constitutes a major problem in commercial pig farming worldwide. Lower weight gains in infected pigs probably result from impaired nutrient absorption. This study investigated intestinal nutrient transport in 4 groups of 6 pigs each, which were inoculated with 30 living adult A. suum , or antigen fractions consisting of (1) total excretory–secretory (ES) antigens of adult worms, (2) ES antigens secreted exclusively from the parasites' body surface (trans-cuticular ES) and (3) cuticular somatic antigens of A. suum , compared to placebo-treated controls. Three days after inoculation into the gastrointestinal tract, glucose, alanine and glycyl-l -glutamine transport was measured in the duodenum, jejunum and ileum using Ussing chambers. Transcription of relevant genes [sodium glucose cotransporter 1 (SGLT1), glucose transporter 1 (GLUT1), GLUT2, hypoxia-inducible factor 1-alpha (Hif1α ), interleukin-4 (IL-4), IL-13, signal transducer and activator of transcription 6 (STAT6), peptide transporter 1 (PepT1)] and expression of transport proteins [SGLT1, phosphorylated SGLT1, GLUT2, Na+/K+-ATPase, amino acid transporter A (ASCT1), PepT1] were studied. Although no significant functional changes were noted after exposure to adult A. suum , a significant downregulation of jejunal GLUT1, STAT6, Hif1α and PepT1 transcription as well as ileal GLUT2 and PepT1 expression indicates a negative impact of infection on transport physiology. Therefore, the exposure period of 3 days may have been insufficient for functional alterations to become apparent. In contrast, A. suum antigens mainly induced an upregulation of transport processes and an increase in transcription of relevant genes in the duodenum and jejunum, possibly as a compensatory reaction after a transient downregulation. In the ileum, a consistent pattern of downregulation was observed in all inoculated groups, in line with the hypothesis of impaired nutrient transport.

Efficient and Scalable Process to Produce Novel and Highly Bioactive Purified Cytosolic Crystals from Bacillus thuringiensis

Bacillus thuringiensis (Bt) is a Gram-positive soil bacterium that is widely and safely applied in the environment as an insecticide for combatting insect pests that damage crops or are disease vectors. Dominant active ingredients made by Bt are insect-killing crystal (Cry) proteins released as crystalline inclusions upon bacterial sporulation. Some Bt Cry proteins, e.g., Cry5B (formally Cry5Ba1), target nematodes (roundworms) and show exceptional promise as anthelmintics (cures for parasitic nematode diseases). We have recently described inactivated bacteria with cytosolic crystal(s) (IBaCC) in which bioactive Bt Cry crystals (containing Cry5B) are fully contained within the cytosol of dead bacterial ghosts. Here, we demonstrate that these IBaCC-trapped Cry5B crystals can be liberated and purified away from cellular constituents, yielding purified cytosolic crystals (PCC). Cry5B PCC contains ~95% Cry5B protein out of the total protein content. Cry5B PCC is highly bioactive against parasitic nematode larvae and adults in vitro. Cry5B PCC is also highly active in vivo against experimental human hookworm and Ascaris infections in rodents. The process was scaled up to the 100-liter scale to produce PCC for a pilot study to treat two foals infected with the ascarid Parascaris spp. Single-dose Cry5B PCC brought the fecal egg counts of both foals to zero. These studies describe the process for the scalable production of purified Bt crystals and define a new and attractive pharmaceutical ingredient form of Bt Cry proteins.

IMPORTANCEBacillus thuringiensis crystal proteins are widely and safely used as insecticides. Recent studies have shown they also can cure gastrointestinal parasitic worm (nematode) infections when ingested. However, reproducible, scalable, and practical techniques for purifying these proteins have been lacking. Here, we address this severe limitation and present scalable and practical methods for large-scale purification of potently bioactive B. thuringiensis crystals and crystal proteins. The resultant product, called purified cytosolic crystals (PCC), is highly compatible with ingestible drug delivery and formulation. Furthermore, there are growing applications in agriculture and insect control where access to large quantities of purified crystal proteins is desirable and where these methods will find great utility.

Genetic diversity and identity of Ascaris worms from human and pig hosts in Thailand

Ascaris roundworms are of public health and socio-economic importance worldwide. They are conventionally attributed to two taxa - A. lumbricoides infecting principally human and A. suum infecting principally pig. Phylogenomic analysis has revealed that Ascaris worms from both human and pig are represented in Clades A and B. A recent study indicates that the Ascaris worms from human and pig in Thailand belong to Clade A. We examined adult Ascaris worms from human and pig in Thailand by means of the partial sequences of three mitochondrial genes (cox1, cox2 and nad1) and concatenation of these genes. Phylogenomic analysis indicates that two isolates (H1,H2) of A. lumbricoides from human belonged to Clade B; one isolate (H3) belonged to Clade A (based on cox1, cox2 and concatenated sequences) or as an outlier to Clades A and B (based on nad1 sequences). All the eight isolates of A. suum from pig clustered in Clade A. The partial nad1 and the concatenated sequences revealed two lineages of A. suum isolates which were distinct from the two A. lumbricoides isolates of Clade B. It is evident that greater genetic diversity, and a more robust phylogeny, could be uncovered by the application of multiple genes. In sum, the present study reveals the presence in Thailand of A. lumbricoides from human in Clades A and B which necessitates appropriate treatment and control measures; Clades A and B have been reported to contain haplotypes of Ascaris worms from both human and pig in other parts of the world. A country wide study is needed to elucidate the identity, distribution, prevalence, cross transmission, genetic diversity and phylogeny of the Ascaris worms in Thailand.

Expression and Secretion of Circular RNAs in the Parasitic Nematode, Ascaris suum

Circular RNAs (circRNAs) are a recently identified RNA species with emerging functional roles as microRNA (miRNA) and protein sponges, regulators of gene transcription and translation, and modulators of fundamental biological processes including immunoregulation. Relevant to this study, circRNAs have recently been described in the parasitic nematode, Haemonchus contortus, suggesting they may have functionally important roles in parasites. Given their involvement in regulating biological processes, a better understanding of their role in parasites could be leveraged for future control efforts. Here, we report the use of next-generation sequencing to identify 1,997 distinct circRNAs expressed in adult female stages of the gastrointestinal parasitic nematode, Ascaris suum. We describe spatial expression in the ovary-enriched and body wall muscle, and also report circRNA presence in extracellular vesicles (EVs) secreted by the parasite into the external environment. Further, we used an in-silico approach to predict that a subset of Ascaris circRNAs bind both endogenous parasite miRNAs as well as human host miRNAs, suggesting they could be functional as both endogenous and exogenous miRNA sponges to alter gene expression. There was not a strong correlation between Ascaris circRNA length and endogenous miRNA interactions, indicating Ascaris circRNAs are enriched for Ascaris miRNA binding sites, but that human miRNAs were predicted form a more thermodynamically stable bond with Ascaris circRNAs. These results suggest that secreted circRNAs could be interacting with host miRNAs at the host-parasite interface and influencing host gene transcription. Lastly, although we have previously found that therapeutically relevant concentrations of the anthelmintic drug ivermectin inhibited EV release from parasitic nematodes, we did not observe a direct effect of ivermectin treatment on Ascaris circRNAs expression or secretion.

Development of allele-specific PCR methodology (AS-PCR) to screening A. lumbricoides and A. suum

Ascaris lumbricoides and Ascaris suum are described as helminths that infect humans and pigs, respectively. It is estimated that infection by A. lumbricoides affects about 447 million individuals living in tropical regions of developing countries. However, there is an increasing number of cases of human ascariasis in countries with no recent history of autochthonous infection by A. lumbricoides. In these places, pigs have been incriminated as the main source of human infection. Conventional parasitological diagnosis does not allow species-specific identification, and the real epidemiological scenario of human and swine ascariasis is still uncertain. Therefore, this work presents the application of a species-specific molecular diagnosis, based on the allele-specific PCR methodology (AS-PCR), using the Internal Transcript Space 1 (ITS-1) of the ribosomal DNA, as a target for differentiating between the two species, using DNA obtained from eggs. To validate the methodology, stool samples positive for Ascaris spp, were obtained from 68 humans from seven Brazilian states and from six pigs from the state of Minas Gerais. All samples obtained from humans were genotyped as A. lumbricoides and all samples obtained from swine were genotyped as A. suum. These results are in agreement with the literature, which demonstrates that in most endemic regions, transmission cycles are separate. Therefore, the execution of this work allowed the availability of a useful methodology for the differential diagnosis of the species, which may contribute to the characterization of the real epidemiological profile of human and swine ascariasis, and to the implementation of future control strategies.

Burdens of Ascaris spp. and Cryptosporidium spp. parasites in farm pigs in Ghana

BACKGROUND

Worldwide, intestinal parasites significantly affect the health and production of pigs.

OBJECTIVE

This study assessed the prevalence of Ascaris and Cryptosporidium infection in pigs in the Ejisu-Juaben Municipality of Ghana.

METHOD

Faecal samples from two hundred (200) pigs on four different farms (labelled A, B, C, D) were processed using the Kinyoun modified Ziehl-Neelsen method for Cryptosporidium and the Formol-ether sedimentation method for Ascaris and microscopically examined to identify parasites to the genus level.

RESULTS

The prevalence of Ascaris and Cryptosporidium in the pigs was 76% and 77%, respectively. The weaners had the highest Ascaris prevalence (96.15%) with the piglets recording the least (59.25%). On the other hand, the piglets had the highest prevalence (88.89%) for Cryptosporidium with the boars, sows and weaners recording 75.86%, 75.42% and 73.08% respectively. The prevalence of Ascaris was high in farm D (78.57%) while Cryptosporidium was highest in farm C (86.11%). Generally, there was a significant difference (p = 0.044) in the mean distribution of Cryptosporidium in the pigs.

CONCLUSION

The high burden of Ascaris and Cryptosporidium infections in the pigs suggest the need to adopt and implement effective control measures.

Beyond transcortical channels, a supra-parietal vascular plexus: A newly recognized anatomical feature

Survey of trans-cortical channels across mammalian phylogeny exposes a previously unrecognized phenomena, localized to the most caudal third of a Sus scrofa parietal. The current study is performed to assess the nature, ontogeny and phylogenetic distribution of this phenomenon. Dissection of a fresh Sus scrofa is performed to characterize the nature of these structures and assess the relationship of the phenomenon to overlying tissues. The external surface of the parietal region of the skulls of recent Artiodactyla, Perissodactyla, Lagomorpha and Rodentia and Pleistocene Platygonus compressus are systematically examined by surface microscopy. Dissection of the parietal region of a Sus scrofa head revealed a structure localized to the most caudal third of the parietal bone. It is composed of anastomosing blood vessels interposed between the dermis and bone. The phenomenon is present among Artiodactyla in all examined Suidae and Tayassuidae, but limited among Cervidae to Odocoileus and apparently limited among Perissodactyla to Tapiridae, both extant and extinct and independent of sex and age. A previously undescribed anatomic structure is observed during survey of trans-cortical parietal circulation. There is connection between the structure and parietal diploic vessels. Interpreted as a vascular plexus, the possibility of a countercurrent system for brain thermoregulation is considered.

Human-type and pig-type Ascaris hybrids found in pigs

The discovery of hybrids between Ascaris lumbricoides and Ascaris suum has complicated our understanding of the relationship between the two species. We examined the same Ascaris specimens (48 from humans and 48 from pigs) using two methods: microsatellite markers combined with Bayesian clustering and PCR-RFLP of the nuclear internal transcribed spacer region. The results obtained by the two methods were inconsistent but showed that hybrid Ascaris identified through both approaches could infect pigs. The results of this study suggest that PCR-RFLP of ITS alone is not suitable for molecular identification of human-type and pig-type Ascaris hybrids. Use of multiple SSR markers combined with Bayesian analysis was the most reliable method in our study. Our results indicate that, in addition to host-specific Ascaris types, there may be some that do not show host specificity. Our results show for the first time that hybrid individuals can infect pigs as well as humans. This study has important theoretical and practical implications, including suggesting the need to re-evaluate long-term ascariasis control strategies.

What lies behind the curtain: Cryptic diversity in helminth parasites of human and veterinary importance

Parasite cryptic species are morphologically indistinguishable but genetically distinct organisms, leading to taxa with unclear species boundaries. Speciation mechanisms such as cospeciation, host colonization, taxon pulse, and oscillation may lead to the emergence of cryptic species, influencing host-parasite interactions, parasite ecology, distribution, and biodiversity. The study of cryptic species diversity in helminth parasites of human and veterinary importance has gained relevance, since their distribution may affect clinical and epidemiological features such as pathogenicity, virulence, drug resistance and susceptibility, mortality, and morbidity, ultimately affecting patient management, course, and outcome of treatment. At the same time, the need for recognition of cryptic species diversity has implied a transition from morphological to molecular diagnostic methods, which are becoming more available and accessible in parasitology. Here, we discuss the general approaches for cryptic species delineation and summarize some examples found in nematodes, trematodes and cestodes of medical and veterinary importance, along with the clinical implications of their taxonomic status. Lastly, we highlight the need for the correct interpretation of molecular information, and the correct use of definitions when reporting or describing new cryptic species in parasitology, since molecular and morphological data should be integrated whenever possible.

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Cryptic diversity has been described in helminths of human and animal importance.

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Cryptic species are morphologically indistinguishable but genetically distinct organisms.

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These entities emerge by different evolutionary and speciation mechanisms.

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Analysis of molecular and morphological data is needed for cryptic species delimitation.

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Cryptic diversity may affect pathogenicity, virulence and drug resistance of helminths.

A historical and systematic overview of Ascaris vaccine development

Ascariasis is the most prevalent helminth infection in the world and leads to significant, life-long morbidity, particularly in young children. Current efforts to control and eradicate ascariasis in endemic regions have been met with significant challenges including high-rates of re-infection and potential development of anthelminthic drug resistance. Vaccines against ascariasis are a key tool that could break the transmission cycle and lead to disease eradication globally. Evolution of the Ascaris vaccine pipeline has progressed, however no vaccine product has been brought to human clinical trials to date. Advancement in recombinant protein technology may provide the first step in generating an Ascaris vaccine as well as a pan-helminthic vaccine ready for human trials. However, several roadblocks remain and investment in new technologies will be important to develop a successful human Ascaris vaccine that is critically needed to prevent significant morbidity in Ascaris-endemic regions around the world.

An annotated checklist of the eukaryotic parasites of humans, exclusive of fungi and algae

The classification of "parasites" in the medical field is a challenging notion, a group which historically has included all eukaryotes exclusive of fungi that invade and derive resources from the human host. Since antiquity, humans have been identifying and documenting parasitic infections, and this collective catalog of parasitic agents has expanded considerably with technology. As our understanding of species boundaries and the use of molecular tools has evolved, so has our concept of the taxonomy of human parasites. Consequently, new species have been recognized while others have been relegated to synonyms. On the other hand, the decline of expertise in classical parasitology and limited curricula have led to a loss of awareness of many rarely encountered species. Here, we provide a comprehensive checklist of all reported eukaryotic organisms (excluding fungi and allied taxa) parasitizing humans resulting in 274 genus-group taxa and 848 species-group taxa. For each species, or genus where indicated, a concise summary of geographic distribution, natural hosts, route of transmission and site within human host, and vectored pathogens are presented. Ubiquitous, human-adapted species as well as very rare, incidental zoonotic organisms are discussed in this annotated checklist. We also provide a list of 79 excluded genera and species that have been previously reported as human parasites but are not believed to be true human parasites or represent misidentifications or taxonomic changes.

Ascaris suum Nutrient Uptake and Metabolic Release, and Modulation of Host Intestinal Nutrient Transport by Excretory-Secretory and Cuticle Antigens In Vitro

Ascaris suum, the most important pig parasite, also infects humans as a zoonotic pathogen. Malabsorption upon infection probably results from impaired nutrient transport, presumably mediated by the parasite’s excretory-secretory (ES) or cuticle somatic (CSO) antigens. The present study investigated the electrogenic transport (ΔI_sc) of glucose, alanine and the dipeptide glycyl-l-glutamine (glygln), as well as glucose net flux rates in pig jejunal tissue after in vitro exposure to adult A. suum total ES or CSO antigens in Ussing chambers. ΔI_sc of glucose, alanine and glucose net flux rate were significantly decreased after one hour of exposure to total ES antigen. In contrast, CSO antigens increased the transport of glygln. Additionally, nutrient uptake and ES antigen pattern were compared in culture medium from untreated adult worms and those with sealed mouth and anal openings. Untreated worms completely absorbed glucose, while cuticular absorption in sealed worms led to 90% reduction. Amino acid absorption was 30% less effective in sealed worms, and ammonia excretion decreased by 20%. Overall, the results show that A. suum total ES antigen rapidly impairs nutrient transport in vitro. Future studies confirming the results in vivo, narrowing down the ES components responsible and investigating underlying molecular mechanisms are needed.

Ascariasis in a 75-year-old man with small bowel volvulus: a case report

Background

Ascaris lumbricoides and Ascaris suum are the most common soil-transmitted helminths of humans and pigs, respectively. The zoonotic potential of A. suum has been a matter of debate for decades. This study was aimed to present a case of human ascariasis caused by A. suum in southern Italy.

Case presentation

A 75-year-old man presented to the department of surgery in Avellino (southern Italy) complaining of abdominal pain and vomiting. Physical examination revealed bloating and abdominal tenderness. A computed tomography scan showed air-fluid levels and small bowel distension. During exploratory laparotomy a small bowel volvulus with mesenteritis was evident and surprisingly an intraluminal worm was detected. The worm was removed with a small enterotomy and identified as an adult female of A. suum based on morphological and molecular analysis. Faecal examination revealed the presence of unfertilized Ascaris eggs with an intensity of 16 eggs per gram (EPG) of faeces. The patient was treated with mebendanzole 100 mg twice a day for 3 days. The post-operative course was regular with re-alimentation after 3 days and discharge after 12 days.

Conclusions

This report shows as A. suum can function as a relevant agent of human zoonosis. Therefore, in patients with bowel obstruction with no evident aetiology a helminthic infestation should be considered for an accurate diagnosis, especially in patients living in rural areas.

Sensitive and semiquantitative detection of soil-transmitted helminth infection in stool using a recombinase polymerase amplification-based assay

Background

Soil-transmitted helminths (STHs) are parasitic nematodes that inhabit the human intestine. They affect more than 1.5 billion people worldwide, causing physical and cognitive impairment in children. The global strategy to control STH infection includes periodic mass drug administration (MDA) based on the results of diagnostic testing among populations at risk, but the current microscopy method for detecting infection has diminished sensitivity as the intensity of infection decreases. Thus, improved diagnostic tools are needed to support decision-making for STH control programs.

Methodology

We developed a nucleic acid amplification test based on recombinase polymerase amplification (RPA) technology to detect STH in stool. We designed primers and probes for each of the four STH species, optimized the assay, and then verified its performance using clinical stool samples.

Principal findings

Each RPA assay was as sensitive as a real-time polymerase chain reaction (PCR) assay in detecting copies of cloned target DNA sequences. The RPA assay amplified the target in DNA extracted from human stool samples that were positive for STH based on the Kato-Katz method, with no cross-reactivity of the non-target genomic DNA. When tested with clinical stool samples from patients with infections of light, moderate, and heavy intensity, the RPA assays demonstrated performance comparable to that of real-time PCR, with better results than Kato-Katz. This new rapid, sensitive and field-deployable method for detecting STH infections can help STH control programs achieve their goals.

Conclusions

Semi-quantitation of target by RPA assay is possible and is comparable to real-time PCR. With proper instrumentation, RPA assays can provide robust, semi-quantification of STH DNA targets as an alternative field-deployable indicator to counts of helminth eggs for assessing infection intensity.

More than 1.5 billion people are infected with parasitic intestinal worms called soil-transmitted helminths. Infection is transmitted by helminth eggs in human feces, which contaminate soil in areas with poor sanitation. Adverse health effects include physical and cognitive impairment in children. A key strategy to control infection is periodic mass drug administration for populations with a high prevalence of disease based on the results of diagnostic testing. The current microscopy method for detecting infection, however, has limited ability to detect disease as the intensity of infection decreases with repeated mass drug administration. To address limitations of current diagnostic methods, we developed a novel technique to diagnose infections, including those at very low levels of intensity, by detecting helminth DNA in stool samples. Our initial studies suggest that the new diagnostic technique reliably detects the presence of intestinal worms, even at low intensities of infection, and may be more useful than currently available diagnostic tools for guiding the use of periodic mass drug administration to eliminate disease in low-resource settings.

Dog care and parasitosis in a rural community of Patagonia: An integrative approach

Human interaction with dogs can potentially lead to zoonoses. The aim of this integrative approach is to describe the relationship between dog parasites, dog care, and the human population of a rural Patagonian village. Surveys were carried out to evaluate owners' attitudes towards dogs, and coproparasitological and coproELISA analyses were performed to determine parasitic infection values. Fur samples and vegetable garden soil were also analyzed. A multivariate regression was performed to identify factors determining infection. All households owned at least one dog, of which only 54.9% had been dewormed in the past three months, and almost half of which were allowed to roam freely. Dogs with protozoan and helminth infections represented 68.8% of the total, 50% being parasitized by helminths of 7 species, including the zoonotic Toxocara canis, Uncinaria sp. Ancylostoma sp. and Echinococcus sp. All hair samples were negative, but 42.8% of vegetable gardens harbored Ancylostomatidae larvae. Statistical analyses indicated that the predictor "time since last deworming" explained infections by Cryptosporidium sp. and helminths, while the predictors "number of dogs per household", "sex", and "freedom to roam" explained the infections by helminths. This shows that the longer the time interval since the last deworming treatment, the greater the probability of a dog being infected by some type of parasite, either Cryptosporidium sp. or a helminth. On the other hand, the probability of being infected by helminths increased when there was more than one dog in the household. Furthermore, male dogs and dogs allowed to roam freely were more likely to be infected. Considering the inadequate care and sanitary status of dogs infected with zoonotic species, it is necessary to raise awareness of the need for responsible care of dogs.

Lectin-Mediated Bacterial Modulation by the Intestinal Nematode Ascaris suum

Ascariasis is a global health problem for humans and animals. Adult Ascaris nematodes are long-lived in the host intestine where they interact with host cells as well as members of the microbiota resulting in chronic infections. Nematode interactions with host cells and the microbial environment are prominently mediated by parasite-secreted proteins and peptides possessing immunomodulatory and antimicrobial activities. Previously, we discovered the C-type lectin protein AsCTL-42 in the secreted products of adult Ascaris worms. Here we tested recombinant AsCTL-42 for its ability to interact with bacterial and host cells. We found that AsCTL-42 lacks bactericidal activity but neutralized bacterial cells without killing them. Treatment of bacterial cells with AsCTL-42 reduced invasion of intestinal epithelial cells by Salmonella. Furthermore, AsCTL-42 interacted with host myeloid C-type lectin receptors. Thus, AsCTL-42 is a parasite protein involved in the triad relationship between Ascaris, host cells, and the microbiota.

Genotyping of Ascaris spp. infecting humans and pigs in Italy, Slovakia and Colombia

BACKGROUND

The systematics and taxonomy of Ascaris lumbricoides and Ascaris suum, two of the world's most widespread nematodes, still represent a highly debated scientific issue. Two different transmission scenarios have been described according to endemicity: separated host-specific transmission cycles in endemic regions, and a single pool of infection shared by humans and pigs in non-endemic regions. The swine roundworm A. suum is now recognized as an important cause of human ascariasis also in endemic areas such as China, where cross-infections and hybridization have also been reported, as well as in non-endemic regions like Italy. This study aimed to investigate the molecular epidemiology of human and pig ascariasis in three countries representing different epidemiological scenarios: Italy as a non-endemic country, Colombia as an endemic country, and Slovakia as a non-endemic country, but with a poor socio-economic context linked to some focal populations of Roma settlements.

MATERIALS AND METHODS

A total of 237 nematodes were analysed: 46 from Colombia (13 from humans, 33 from pigs), 114 from Slovakia (20 from humans, 94 from pigs) and 77 from Italy (17 from humans and 60 from pigs). Genotyping by PCR-RFLP of nuclear (ITS) and sequencing of mitochondrial (cox1) target regions were performed. ITS genotypes were used to estimate the Hardy-Weinberg (HW) equilibrium according to hosts and country of origin. The partial cox1 sequences were used to analyse genetic polymorphisms according to hosts and country of origin, as well as to infer the network of haplotypes, their evolutionary relationships and geographical distribution.

RESULTS

110 quality cox1 sequences were obtained. Haplotype network revealed three main groups corresponding to clade A, B and C. Clade C included most of the human cases from Italy, while those from Slovakia and Colombia were grouped in clade B. Ascaris from Italian and Colombian pigs showed HW equilibrium at the ITS marker, while disequilibrium was found in A. lumbricoides from Slovak pigs, which suggest a high unexpected amount of roundworms of human origin circulating also in pigs.

CONCLUSIONS

This study updates and extends the current understanding of Ascaris species and genotypes circulating in different epidemiological scenarios, with particular attention to the inclusion of human-derived Ascaris in the phylogenetic cluster C. Despite the evidence of HW equilibrium in the ITS in pig-derived Italian samples, the amount of genetic variation seems to support the existence of two closely related species.

Effect of sanitation improvements on soil-transmitted helminth eggs in courtyard soil from rural Bangladesh: Evidence from a cluster-randomized controlled trial

Improved sanitation has been hypothesized to reduce soil-transmitted helminth (STH) infections by reducing the prevalence and concentration of STH eggs/larvae in soil. We evaluated the effect of a randomized sanitation program (providing households with an improved dual-pit latrine, tools for child/animal feces management, and behavioral messaging) on reducing the prevalence and concentration of STH eggs in soil from household courtyards. We collected soil samples from 1405 households enrolled in the sanitation intervention (n = 419) and control (n = 914) groups of a cluster-randomized controlled trial (WASH Benefits) in rural Bangladesh approximately 2 years after the initiation of the interventions. We analyzed samples for Ascaris lumbricoides, Trichuris trichiura, and hookworm eggs by microscopy. We estimated prevalence ratios (PR) and egg count ratio (ECR) to compare the prevalence of STH eggs and arithmetic and geometric mean egg counts for STH eggs per gram of soil in the sanitation and control arms. Among intervention households, latrines achieved high and sustained user uptake by adults while child open defecation remained common and most households did not dispose of child feces hygienically. In courtyard soil from control households, the prevalence of any STH eggs was 75.7% and the prevalence of any larvated STH eggs was 67.3%. A. lumbricoides was detected in 63.0% of control samples and T. trichiura in 55.7% of control samples; hookworm was not detected in any sample. In the control arm, the arithmetic mean egg count for any STH was 3.96 eggs/dry gram, while the geometric mean was 1.58 eggs/dry gram. There was no difference between the intervention and control groups in the prevalence of any STH eggs (PR = 0.98 (95% CI: 0.91, 1.05)) or mean egg counts (ECR = 0.08 (95% CI: -0.10, 0.26) for geometric mean and 0.07 (95% CI: -0.22, 0.37) for arithmetic mean). Adjusted models gave similar results. A compound-level sanitation intervention that provided improved latrines and tools for disposal of child and animal feces did not have an impact on STH eggs in soil. In order to effectively reduce the prevalence and concentration of STH eggs in the environment, sustained, widespread use of sanitation strategies to isolate and hygienically dispose of child and animal feces may need to complement traditional strategies for containment of adult human feces. Trial Registration: NCT01590095.

Unraveling Ascaris suum experimental infection in humans

Ascaris lumbricoides and A. suum are two closely related parasites that infect humans and pigs. The zoonotic potential of A. suum has been a matter of debate for decades. Here we sought to investigate the potential human infection by A. suum and its immunological alterations. We orally infected five healthy human subjects with eggs embraced by A. suum. The infection was monitored for symptoms and possible respiratory changes, by an interdisciplinary health team. Parasitological, hematological analyses, serum immunoglobulin, cytokine profiles, and gene expression were evaluated during the infection. Our results show that A. suum is able to infect and complete the cycle in humans causing A. lumbricoides similar symptoms, including, cough, headache, diarrhea, respiratory discomfort and chest x-ray alterations coinciding with larvae migration in the lungs. We also observed activation of the immune system with production of IgM and IgG and a Th2/Th17 response with downregulation of genes related to Th1 and apoptosis. PCA (Principal componts analysis) show that infection with A. suum leads to a change in the immune landscape of the human host. Our data reinforce the zoonotic capacity of A. suum and bring a new perspective on the understanding of the immune response against this parasite.

An inactivated bacterium (paraprobiotic) expressing Bacillus thuringiensis Cry5B as a therapeutic for Ascaris and Parascaris spp. infections in large animals

Ascaris and Parascaris are important parasites in the family Ascarididae, large, ubiquitous intestinal-dwelling nematodes infecting all classes of vertebrates. Parasitic nematode drug resistance in veterinary medicine and drug recalcitrance in human medicine are increasing worldwide, with few if any new therapeutic classes on the horizon. Some of these parasites are zoonotic, e.g., Ascaris is passed from humans to pigs and vice versa. The development of new therapies against this family of parasites would have major implications for both human and livestock health. Here we tested the therapeutic ability of a paraprobiotic or dead probiotic that expresses the Bacillus thuringiensis Cry5B protein with known anthelmintic properties, against zoonotic Ascaris suum and Parascaris spp. This paraprobiotic, known as IBaCC, intoxicated A. suum larvae in vitro and was highly effective in vivo against intestinal A. suum infections in a new mouse model for this parasite. Fermentation was scaled up to 350 l to treat pigs and horses. Single dose Cry5B IBaCC nearly completely cleared A. suum infections in pigs. Furthermore, single dose Cry5B IBaCC drove fecal egg counts in Parascaris-infected foals to zero, showing at least parity with, and potential superiority to, current efficacy of anthelmintics used against this parasite. Cry5B IBaCC therefore represents a new, paraprobiotic One Health approach towards targeting Ascarididae that is safe, effective, massively scalable, stable, and useful in human and veterinary medicine in both the developed and developing regions of the world.

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IBaCC is Bacillus thuringiensis Cry5B protein crystals trapped inside dead bacteria.

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IBaCC intoxicates Ascaris suum intestinal parasitic nematodes in vitro.

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IBaCC is highly effective against A. suum parasites in vivo in mice and pigs.

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IBaCC is highly effective against related Parascaris parasites in foals.

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IBaCC represents a new paradigm for treating ascarid parasites of humans and animals.

Diversity of parasites in two captive chimpanzee populations in southern Gabon

Captive chimpanzees living in confined environments like sanctuaries or primatology centers are frequently affected by gastrointestinal parasites. Some of these are likely to be transmitted to humans and may seriously affect public health. However little information is currently available on the gastrointestinal parasites of primates living in such environments. Here, we characterize the diversity and prevalence of gastrointestinal parasites in two populations of captive chimpanzees living in south-eastern Gabon. Our study reveals that at least nine parasite species infect the chimpanzees with high prevalence, including several helminths (Ascaris spp., Enterobius spp., Strongyloides spp., Trichuris spp., Hymenolepis spp., Mammomonogamus spp), three protozoa (Balantioides spp., Entamoeba spp. and Troglodytella spp) and several unidentified parasites. All the parasite taxa we identified had previously been identified in other primates, including humans. Age, sex and site type may influence infection rates and/or parasite diversity found in a particular host.

Quantitative lipidomic analysis of Ascaris suum

Ascaris is a soil-transmitted nematode that causes ascariasis, a neglected tropical disease affecting predominantly children and adolescents in the tropics and subtropics. Approximately 0.8 billion people are affected worldwide, equating to 0.86 million disability-adjusted life-years (DALYs). Exploring the molecular biology of Ascaris is important to gain a better understanding of the host-parasite interactions and disease processes, and supports the development of novel interventions. Although advances have been made in the genomics, transcriptomics and proteomics of Ascaris, its lipidome has received very limited attention. Lipidomics is an important sub-discipline of systems biology, focused on exploring lipids profiles in tissues and cells, and elucidating their biological and metabolic roles. Here, we characterised the lipidomes of key developmental stages and organ systems of Ascaris of porcine origin via high throughput LC-MS/MS. In total, > 500 lipid species belonging to 18 lipid classes within three lipid categories were identified and quantified–in precise molar amounts in relation to the dry weight of worm material–in different developmental stages/sexes and organ systems. The results showed substantial differences in the composition and abundance of lipids with key roles in cellular processes and functions (e.g. energy storage regulation and membrane structure) among distinct stages and among organ systems, likely reflecting differing demands for lipids, depending on stage of growth and development as well as the need to adapt to constantly changing environments within and outside of the host animal. This work provides the first step toward understanding the biology of lipids in Ascaris, with possibilities to work toward designing new interventions against ascariasis.

Lipids are of vital importance in the biology of parasitic worms, particularly in relation to cellular membranes, energy storage, and intra- and intercellular signalling. However, very little is known about the biology of lipids in parasitic nematodes. Using a high-throughput LC-MS/MS approach, we characterised the first global lipidome for Ascaris. We investigated the lipid composition and abundance in key developmental stages/sexes as well as the organ systems of Ascaris. We observed substantial differences in lipid composition and abundance among these stages/sexes and among the organ systems studied. The findings provide a basis to start to understand lipid biology in Ascaris, with possible implications for developing new interventions against ascariasis.

Molecular evidence of hybridization between pig and human Ascaris indicates an interbred species complex infecting humans

Human ascariasis is a major neglected tropical disease caused by the nematode Ascaris lumbricoides. We report a 296 megabase (Mb) reference-quality genome comprised of 17,902 protein-coding genes derived from a single, representative Ascaris worm. An additional 68 worms were collected from 60 human hosts in Kenyan villages where pig husbandry is rare. Notably, the majority of these worms (63/68) possessed mitochondrial genomes that clustered closer to the pig parasite Ascaris suum than to A. lumbricoides. Comparative phylogenomic analyses identified over 11 million nuclear-encoded SNPs but just two distinct genetic types that had recombined across the genomes analyzed. The nuclear genomes had extensive heterozygosity, and all samples existed as genetic mosaics with either A. suum-like or A. lumbricoides-like inheritance patterns supporting a highly interbred Ascaris species genetic complex. As no barriers appear to exist for anthroponotic transmission of these 'hybrid' worms, a one-health approach to control the spread of human ascariasis will be necessary.

Detection of Ascaris lumbricoides infection by ABA-1 coproantigen ELISA

Intestinal worms, or soil-transmitted helminths (STHs), affect hundreds of millions of people in all tropical and subtropical regions of the world. The most prevalent STH is Ascaris lumbricoides. Through large-scale deworming programs, World Health Organization aims to reduce morbidity, caused by moderate-to-heavy intensity infections, below 2%. In order to monitor these control programs, stool samples are examined microscopically for the presence of worm eggs. This procedure requires well-trained personnel and is known to show variability between different operators interpreting the slides. We have investigated whether ABA-1, one of the excretory-secretory products of A. lumbricoides can be used as a coproantigen marker for infection with this parasite. Polyclonal antibodies were generated and a coproantigen ELISA was developed. Using this ELISA, it was found that ABA-1 in stool detected Ascaris infection with a sensitivity of 91.5% and a specificity of 95.3%. Our results also demonstrate that there is a correlation between ABA-1 levels in stool and A. lumbricoides DNA detected in stool. Using a threshold of 18.2 ng/g stool the ABA-1 ELISA correctly assigned 68.4% of infected individuals to the moderate-to-heavy intensity infection group, with a specificity of 97.1%. Furthermore, the levels of ABA-1 in stool were shown to rapidly and strongly decrease upon administration of a standard anthelminthic treatment (single oral dose of 400 mg albendazole). In an Ascaris suum infection model in pigs, it was found that ABA-1 remained undetectable until day 28 and was detected at day 42 or 56, concurrent with the appearance of worm eggs in the stool. This report demonstrates that ABA-1 can be considered an Ascaris -specific coproantigen marker that can be used to monitor infection intensity. It also opens the path for development of point-of-care immunoassay-based tests to determine A. lumbricoides infection in stool at the sample collection site.

Surveillance of important bacterial and parasitic infections in Danish wild boars (Sus scrofa)

Background

Similar to the situation in other European countries, Danish wild boars may harbour a wide range of pathogens infectious to humans and domestic pigs. Although wild boars must be kept behind fences in Denmark, hunting and consumption of the meat may cause zoonotic transmission. Moreover, most infections of wild boars are transmissible to domestic pigs, which may have important economic consequences. The aim of this study was to investigate whether Danish wild boars were infected with bacteria and parasites transmissible to humans or domestic pigs: Brucella suis, methicillin-resistant Staphylococcus aureus (MRSA), Salmonella spp., Trichinella spp., lungworms and gastrointestinal parasites, especially Ascaris suum. This is the first study to investigate the prevalence of these important pathogens in Danish wild boars.

Results

Wild boars from eight enclosures were analysed over a 5-year period. All tested wild boars were negative for B. suis (n = 240), MRSA (n = 244), Salmonella spp. (n = 115) and Trichinella spp. (n = 232), while eight parasite genera were identified in the faeces (n = 254): Ascaris suum, Capillaria sp., Cystoisospora suis, Eimeria spp., Metastrongylus sp. (lungworm), Strongyloides ransomi, Trichuris suis and strongylid eggs, i.e. strongyles not identified to the genera. Eimeria spp. and Metastrongylus sp. had the highest prevalence (92.3 and 79.5%, respectively) and were identified in wild boars from all eight enclosures, while the remaining parasite genera were present more sporadically.

Conclusions

Wild boars from Denmark constitute a low risk of transmitting B. suis, MRSA, Salmonella spp. and Trichinella spp. to humans or domestic pigs, while economically important parasites transmissible to domestic pigs are highly prevalent in the wild boar population.

Cellular immune response of asthmatic children in the presence of anti-Ascaris antibody

The presence of anti-Ascaris (anti-Asc) immunoglobin isotypes alters the risk of allergic asthma. In this study, we analyzed the relationships between serum levels of anti-Asc IgE, IgG1, and IgG4, without concurrent infection by the parasite, and the presence of asthma. We measured cytokine levels from Th1, Th2, and Th17 profiles. Children aged 2-14 years old, asthmatics (n = 64), and non-asthmatics (n = 40) were selected according to the International Study of Asthma and Allergies in Childhood criteria. Asthmatic patients who had positive skin allergy tests were considered to have allergic asthma. Stool exams were performed to exclude children who were parasitized by helminths/protozoans and blood samples were collected in non-parasitized individuals. We performed peripheral blood leukocyte counts and in vitro culture following mitogenic stimulation. Levels of cytokines (IL-2, IL-4, IL-6, IL-10, TNF-α, IFN-γ, and IL-17) in the supernatants were measured using a cytometric bead array. Titration of serum total IgE and IgE specific to Ascaris were obtained using ImmunoCAP; IgG1 and IgG4 titers were measured using enzyme-linked immunosorbent assays. Anti-Asc IgE was associated with a higher risk of asthma and an increase in the number of eosinophils and neutrophils. By contrast, anti-Asc IgG1 could be considered a protective factor against asthma, associated with lower levels of circulating neutrophils. There were high levels of IL-6 and TNF-α in asthmatics. Levels of IL-6, but not TNF-α, depended on the presence of anti-Asc IgG1 in serum. Anti-Asc IgE appears to increase risk of asthma, and anti-Asc IgG1 appears to favor decreased neutrophil counts and increased IL-6 levels.

Immune serum-activated human macrophages coordinate with eosinophils to immobilize Ascaris suum larvae

Helminth infection represents a major health problem causing approximately 5 million disability-adjusted life years worldwide. Concerns that repeated anti-helminthic treatment may lead to drug resistance render it important that vaccines are developed but will require increased understanding of the immune-mediated cellular and antibody responses to helminth infection. IL-4 or antibody-activated murine macrophages are known to immobilize parasitic nematode larvae, but few studies have addressed whether this is translatable to human macrophages. In the current study, we investigated the capacity of human macrophages to recognize and attack larval stages of Ascaris suum, a natural porcine parasite that is genetically similar to the human helminth Ascaris lumbricoides. Human macrophages were able to adhere to and trap A suum larvae in the presence of either human or pig serum containing Ascaris-specific antibodies and other factors. Gene expression analysis of serum-activated macrophages revealed that CCL24, a potent eosinophil attractant, was the most upregulated gene following culture with A suum larvae in vitro, and human eosinophils displayed even greater ability to adhere to, and trap, A suum larvae. These data suggest that immune serum-activated macrophages can recruit eosinophils to the site of infection, where they act in concert to immobilize tissue-migrating Ascaris larvae.

African helminth infection out of Africa: Paleoparasitological and paleogenetic investigations in Pretos Novos cemetery, Rio de Janeiro, Brazil (1769-1830)

Pretos Novos cemetery (PNC), Rio de Janeiro, Brazil (1769-1830) was created exclusively to bury enslaved Africans who died upon arrival at the city or before being sold in the slave market. The PNC site may be unique in the Americas in allowing the study of African parasite infections acquired in Africa. We aimed to identify parasites infecting PNC individuals through paleoparasitological and paleogenetic analyses. The bodies had been dismembered, placed in mass graves, and burned, and most human remains collected from the site are highly fragmented and show extensive degradation. Sacrum and pelvic sediments were collected from five individuals along with seven samples of sediment from other areas of the body, as controls. Samples were submitted to three parasitological techniques and, in paleogenetic analysis, to four molecular targets. Larvae, mites, pollen grains, and structure suggestive of plants and fungus were observed, but we found no evidence of helminth infection. Ascaris sp. cytb sequence was recovered in one individual. We emphasize that, even with the extensive degradation of PNC human remains and the process of curation of samples, it was possible to recover helminth aDNA. The origin of PNC individuals confirms that these infections were brought to Brazil from western and central Africa during the colonial era.