Helminth parasites in pigs: New challenges in pig production and current research highlights

Gastrointestinal nematodes in German outdoor-reared pigs based on faecal egg count and next-generation sequencing nemabiome data

BACKGROUND

There is a higher risk for nematode infections associated with outdoor-reared pigs. Next to Ascaris suum, Oesophagostomum dentatum and Trichuris suis, there is the potential of infections with other nodular worm species, Hyostrongylus rubidus, Stongyloides ransomi and Metastrongylus spp. lungworms. Next-generation sequencing methods describing the nemabiome have not yet been established for porcine nematodes.

METHODS

FLOTAC was used for faecal egg counts of porcine gastrointestinal nematodes and lungworms in piglets, fatteners and adults individually. A nemabiome analyses based on ITS-2 gene region metabarcoding was used to differentiate strongyle species. Additionally, questionnaire data was analysed using mixed-effect regression to identify potential risk factors associated with parasite occurrences and egg shedding intensity.

RESULTS

On 15 of 17 farms nematode eggs were detected. Ascaris suum, strongyles and T. suis were detected on 82%, 70% and 35% of the 17 farms, respectively. Lungworms were detected on one out of four farms with access to pasture. Strongyloides ransomi was not detected. 32% (CI 28-36%), 27% (24-31%), 5% (4-7%) and 3% (0.9-8%) of the samples where tested positive for strongyles, A. suum, T. suis and lungworms, respectively. The nemabiome analysis revealed three different strongyle species, with O. dentatum being the most common (mean 93.9%), followed by O. quadrispinulatum (5.9%) and the hookworm Globocephalus urosubulatus (0.1%). The bivariate and multivariate risk factor analyses showed among others that cleaning once a week compared to twice a week increased the odds significantly for being infected with A. suum (OR 78.60) and strongyles (2077.59). Access to pasture was associated with higher odds for A. suum (43.83) and strongyles (14.21). Compared to shallow litter systems, deep litter and free range systems resulted in significant higher odds for strongyles (85.74, 215.59, respectively) and T. suis (200.33, 623.08).

CONCLUSIONS

Infections with A. suum, O. dentatum, O. quadrispinulatum, T. suis, Metastrongylus spp. and G. urosubulatus are present in German outdoor-reared pigs. This is the first report of G. urosubulatus in domestic pigs in Europe. Metabarcoding based on the ITS-2 region is a suitable tool to analyse the porcine nemabiome. Furthermore, management practices have the potential of reducing the risk of parasite infections.

Epidemiology and distribution of gastrointestinal parasites in fattening pig farms in northern Italy

In Italy, pig breeding is characterised by intensive farms in which parasitic diseases often present a subclinical pattern, while being responsible for decreased animal welfare and great economic losses. The present study aimed to assess the prevalence of major parasites in pigs, and, for this purpose, 880 faecal samples of fattening pigs raised in 22 intensive farms located in northern Italy were collected in two different sampling sessions, at the beginning and end of the fattening cycle. For the detection of helminth eggs and coccidian oocysts, a quantitative flotation technique was used, whereas a conventional PCR was performed to confirm the identification of cestode eggs found by copromicroscopic analysis. Moreover, data regarding herd management were collected to assess risk factors for parasite occurrence. A total of 95 samples were positive for at least one parasitic taxon (10.8%); the most detected parasite was Ascaris suum (7.6%), followed by Trichuris suis (1.7%) and Cystoisospora suis (0.9%). Further, eggs with morphometric features compatible with those of Hymenolepis diminuta were detected in 16 samples (1.8%), and the analysis of sequences confirmed the identification of cestode eggs. Statistical analysis showed that large farms and those applying the all-in/all-out system were associated with a lower risk of nematode infection. This study provided data on prevalence and burden of gastrointestinal parasites in two different times of the fattening cycle. It was evidenced that endoparasites are persistent, albeit with low prevalences, and would need specific measures to reduce their effects on both animal health and productivity.

Survey the Occurrence of Globocephalus urosubulatus (Nematoda: Ancylostomatidae) in Wild Boars (Sus scrofa) in the State of São Paulo, Brazil

Although previous studies have characterized the helminth fauna of wild boars kept in captivity in Brazil, records on these helminths in free-ranging animals are still scarce. In view of this, we aimed in our work to investigate the occurrence and morphological and morphometric characteristics of gastrointestinal helminths in wild Sus scrofa from the northwest region of the State of São Paulo, Brazil. The digestive systems of 10 animals (5 males and 5 females of different ages) were used in this study. Each anatomical segment was washed and sieved under running water, and the helminths were separated and identified using light and scanning electron microscopy, according to their morphological characteristics. A total of 2750 (1152 males and 1598 females) nematode specimens were collected from the small intestine of these wild boars, and all of them presented the morphological characteristics of Globocephalus urosubulatus. However, one characteristic is of particular interest because it has not yet been reported in the literature: a marked asymmetry between the lobes and their respective rays of the copulatory bursa, with the left one being larger than the right one. In this research, we identified the presence of G. urosubulatus in all the examined free-ranging wild boars and reported for the first time in the literature the asymmetry in the copulatory bursa.

Serology survey of Ascaris suum and Trichinella spiralis in rural pigs in Southwestern Mexico

BACKGROUND

Parasitic diseases of pigs are a public and veterinary health problem. Helminths influence pork production, whereas backyard pigs can transmit these parasites.

OBJECTIVES

This work aimed to investigate the prevalence of antibodies against Ascaris suum and Trichinella spiralis in backyard pigs from Jamiltepec, Region de la Costa, Oaxaca, in Southwestern Mexico.

METHODS

Six hundred sixty-four serum samples were obtained from backyard pigs from 23 rural villages distributed in 5 municipalities; samples were taken in a non-probabilistic manner with the owner's consent. The presence of serum antibodies against a total extract of A. suum adult worm was determined by ELISA. In contrast, antibodies to the excretion-secretion products of the T. spiralis muscle larva were determined by Western blot.

RESULTS

The global seroprevalence for A. suum was 5.12% and 2.41% for T. spiralis; however, antibodies were only found in 8 villages and distributed in 3 municipalities. The highest frequency of positivity for Ascaris was found in the municipality of Santa Catarina Mechoacán (13.01%), whereas, in Santa María Huazalotitlán, the highest frequency of positivity for Trichinella was found (5.75%). In San Andrés, frequencies were 7.23% and 4.82%, respectively. No statistical differences were observed between populations.

CONCLUSIONS

Our data suggest that helminth transmission is restricted by locality. However, further studies must be conducted to understand the factors limiting this transmission to promote pork meat production in parasite-free zones.

Th2-biased immune responses to body migrating Ascaris larvae in primary infection are associated with pathology but not protection

Helminth infections lead to an overdispersion of the parasites in humans as well as in animals. We asked whether early immune responses against migrating Ascaris larvae are responsible for the unequal distribution of worms in natural host populations and thus investigated a susceptible versus a resistant mouse strain. In mice, the roundworm larvae develop until the lung stage and thus early anti-Ascaris immune responses against the migrating larvae in the liver and lung can be deciphered. Our data show that susceptible C57BL/6 mice respond to Ascaris larval migration significantly stronger compared to resistant CBA mice and the anti-parasite reactivity is associated with pathology. Increased eosinophil recruitment was detected in the liver and lungs, but also in the spleen and peritoneal cavity of susceptible mice on day 8 post infection compared to resistant mice. In serum, eosinophil peroxidase levels were significantly higher only in the susceptible mice, indicating functional activity of the recruited eosinophils. This effect was associated with an increased IL-5/IL-13 production by innate lymphoid cells and CD4+ T cells and a pronounced type 2 macrophage polarization in the lungs of susceptible mice. Furthermore, a comparison of wildtype BALB/c and eosinophil-deficient dblGATA-1 BALB/c mice showed that eosinophils were not essential for the early control of migrating Ascaris larvae. In conclusion, in primary infection, a strong local and systemic type 2 immune response during hepato-tracheal helminth larval migration is associated with pathology rather than protection.

Trichuris Globulosa Von Linstow, 1901 from one-humped camel (Camelus dromedarius) in Egypt: prevalence, morphological and molecular study

BACKGROUND

Trichuris spp. (whipworms) are soil-transmitted helminths distributed worldwide, parasitizing several mammalian hosts such as ruminants, primates, and rodents. Trichuris spp. is one of the most common intestinal parasites affecting both humans and animals, and it can spread directly through the fecal-oral route, resulting in severe illness and financial loss. So, this work aims to detect the frequency of Trichuris spp. in camels in Beheira Governorate, Egypt, and to identify Trichuris spp. through morphometrical studies, molecular analysis, and phylogenetic analysis.

RESULTS

A total of 35 dromedaries out of 127 investigated had Trichuris spp. infection, meaning that the overall prevalence was 27.56%. The age of the camel affected the infection rate, older animals (> 5 years) having a higher prevalence of infection (24%) than animals of ages (< 3 years) (20%) than animals of ages (3-5 years) (19.14%). According to season: Trichuris spp. showed a unique pattern in camels in different seasons: summer (31.25%) > autumn (28.13%) > spring (25.8%) > winter (25%) indicating year-round infection. T. globulosa was identified morphometrically from camels in Beheira Governorate, Egypt. The BLAST analysis revealed the presence of T. globulosa isolate from camels using the Genbank database depending on nuclear small subunit ribosomal RNA (18s) and cytochrome b (Cytb) genes.

CONCLUSION

A high prevalence of T. globulosa was found in camels in Beheira Governorate, Egypt. This is the first report to confirm the identification of T. globulosa from camel based on morphometrical studies and molecular and phylogenetic analysis in Egypt. More thorough studies on the incidence, molecular, and genetic analysis of Trichuris spp. in Egypt are required in addition to camel control programs.

Hepatobiliary Ascariasis in a Piglet

PURPOSE

Ascariasis caused by the helminth Ascaris suum is the most common parasitosis of swine worldwide and it may involve all age categories of pigs. The present study reports an unusual localization of A. suum worms in the biliary system of a piglet slaughtered for human consumption.

METHODS

The liver was subjected to ultrasound scan and pathological examination. The isolated worms were morphologically examined and the DNA was extracted for the molecular identification of the species involved.

RESULTS

A total of 43 preadult nematodes were found within the gallbladder and the bile ducts. Parasites were morphologically identified as belonging to the genus Ascaris and molecularly as A. suum. At gross examination, the liver was moderately enlarged, with the bile ducts severely dilated. A chronic inflammatory infiltrate was noted, often centered around ectatic bile ducts (up to 5 mm in diameter), lined by hyperplastic epithelium and filled with sections of nematodes. The worm sections showed smooth cuticle, coelomyarian musculature, and an intestinal tract lined by columnar, uninucleated cells within a pseudocoelom. The ex vivo ultrasonographic examination of the liver allowed the visualization of several nematodes in the bile duct lumen and could be suggested for in vivo diagnosis. Unfortunately, the absence of the intestine did not allow to define the pathogenesis of the infection.

CONCLUSION

Although, given the unusual nature of this finding, it is difficult to identify predisposing factors for this A. suum localization, it suggests that ascariasis should be considered in the differential diagnosis of pigs with hepatobiliary disease.

Crosstalk between trace elements and T-cell immunity during early-life health in pigs

With gradual ban on the use of antibiotics, the deficiency and excessive use of trace elements in intestinal health is gaining attention. In mammals, trace elements are essential for the development of the immune system, specifically T-cell proliferation, and differentiation. However, there remain significant gaps in our understanding of the effects of certain trace elements on T-cell immune phenotypes and functions in pigs. In this review, we summarize the specificity, development, subpopulations, and responses to pathogens of porcine T cells and the effects of functional trace elements (e.g., iron, copper, zinc, and selenium) on intestinal T-cell immunity during early-life health in pigs. Furthermore, we discuss the current trends of research on the crosstalk mechanisms between trace elements and T-cell immunity. The present review expands our knowledge of the association between trace elements and T-cell immunity and provides an opportunity to utilize the metabolism of trace elements as a target to treat various diseases.

Parasite Prevalence in Feral Swine (Sus scrofa) from the Great Smoky Mountains National Park, USA

Feral swine (Sus scrofa) are an introduced species to the Great Smoky Mountains National Park (GSMNP), US, and serve as carriers of several diseases that are considered a threat to other wildlife, domestic animals, and humans. During 2013 and 2015, fecal samples from 67 feral swine from the GSMNP within both Tennessee and North Carolina, US, were opportunistically collected as part of a feral swine removal program and submitted to the University of Tennessee College of Veterinary Medicine, Knoxville, Tennessee, for parasite screening by centrifugal sugar flotation. Ten taxa from the phyla Acanthocephala, Apicomplexa, and Nematoda were identified: Ascaris spp., Strongylid-type spp., Capillaria spp., Trichuris suis, Metastrongylus spp., Macracanthorhynchus spp., Coccidia, Sarcocystis spp., and Cryptosporidium spp. In 98.5% of samples, at least one parasite was found. No differences in parasite prevalence or species diversity were noted based on state of collection (Tennessee or North Carolina), sex, or age. The high prevalence of gastrointestinal parasites in these feral swine, some of which are zoonotic, represents a potential public health risk as well as a concern for free-range swine farmers.

Profiling of hepatic transcriptomes reveals modulatory effects of parasitic infection on the metabolic response to dietary polyphenols in pigs

Polyphenols are a class of bioactive plant compounds with health-promoting properties, however the interactions between polyphenols and pathogen infection and their cumulative impact on inflammation and metabolic health are not well understood. Here, we investigated if a sub-clinical parasitic infection modulates the hepatic response to dietary polyphenol supplementation in a porcine model. Pigs were fed a diet with or without 1% grape proanthocyanidin (PAC) for 28 days. During the final 14 days of the experiment, half the pigs in each dietary group were inoculated with the parasitic nematode Ascaris suum. Serum biochemistry was measured and hepatic transcriptional responses were determined by RNA-sequencing coupled with gene-set enrichment analysis. A. suum infection resulted in reduced serum phosphate, potassium and calcium, and increased serum iron concentrations. In uninfected pigs, PAC supplementation markedly changed the liver transcriptome including genes related to carbohydrate and lipid metabolism, insulin signaling, and bile acid synthesis. However, during A. suum infection, a separate set of genes were modulated by dietary PAC, indicating that the polyphenol-mediated effects were dependent on infection status. A. suum infection strongly influenced the expression of genes related to cellular metabolism, and, in contrast to the effects of PAC, these changes were mostly identical in both control-fed and PAC-fed pigs. Thus, the hepatic response to infection was mostly unaffected by concurrent polyphenol intake. We conclude that the presence of a commonly occurring parasite substantially influences the outcome of dietary polyphenol supplementation, which may have important relevance for nutritional interventions in populations where intestinal parasitism is widespread.

Ante-mortem and Post-mortem Inspection and Relationship between Findings in a North Albanian Pig Slaughterhouse

In June 2014, Albania was granted EU candidate status, thus starting a process of compliance with the membership criteria. In this context, a modern meat inspection approach in line with the European legislation was applied to a pig slaughterhouse in northern Albania in order to investigate the ante-mortem (AM) and post-mortem (PM) conditions and the relationship between these findings. For this purpose, 3930 pigs divided into 35 batches were evaluated over a 3-month period. The most frequent AM conditions recorded were tail lesions and dyspnea (9.1%), followed by skin (8.9%) and ear lesions (8.5%), while in the PM inspections, pleuritis was the most frequently observed condition (10.2%), followed by pneumonia (8.5%), liver alterations (5.7%), milk spot liver (3.8%), and pericarditis (3.3%). With the exception of liver alterations, the other PM lesions mentioned were positively associated with lesions on the ears (OR = 1.036; p < 0.001) and skin (OR = 1.026; p = 0.011) and dyspnea (OR = 1.021; p = 0.005), confirming the link between these variables and the health and welfare conditions of pigs on farms. Overall, the evidence that emerged from this Albanian slaughterhouse can be considered in line with other European contexts, especially in light of the considerable variability in the data present in the literature.

New genetic lineage of whipworm present in Bactrian camel (Camelus bactrianus)

With a global population of around 35 million in 47 countries, camels play a crucial role in the economy of many marginal and desert areas of the world where they survive in harsh conditions. Nonetheless, there is insufficient knowledge regarding camels' parasite fauna which can reduce their milk and meat production. A molecular study for the Trichuris population of Camelus bactrianus from Spain is presented based on sequences of mitochondrial (cox1, cob, rrnL) and ribosomal (ITS1 and ITS2) DNA regions. Bayesian Inference and Maximum Likelihood methods were used to infer phylogenies for (i) each gene separately, (ii) the combined mitochondrial data, and (iii) the combined mitochondrial and ribosomal dataset. Molecular analyses revealed the existence of two different genetic lineages in the Trichuris parasites populations of C. bactrianus. Future studies should focus on whether there is a coevolution process corresponding to the wild or domestic character of C. bactrianus and Camelus dromedarius. Furthermore, it is necessary to increase integrative taxonomic studies on Trichuris spp. based on morphological, biometric, and molecular data, which will inevitably contribute to our knowledge of the etiology of trichuriasis.

Intestinal roundworm infection in organic and alternative swine farms in the USA

Swine parasites are a challenge for organic and alternative pig farmers and represent suboptimal animal health because use of chemical prophylaxis is not recommended. There is no comprehensive study of how prevalent gastrointestinal parasites are in organic or alternative pig farms across the USA. This study investigates prevalence, abundance, and intensity measures for three intestinal roundworm parasites (Ascaris suum, Oesophagostomum spp. and Trichuris suis) on organic and alternative swine farms by quantifying their eggs in pig feces, pastured soil, and bedding. Nine farms raising pigs in bedded facilities across four states (Iowa, Minnesota, Pennsylvania, and Wisconsin) were sampled, and analysis of parasite egg counts from feces indicate that 88.9%, 55.5%, and 44.4% of farms were infected with A. suum, Oesophagostomum spp. and T. suis, respectively. Prevalence, mean abundance, and mean intensity of eggs per gram (EPG) in feces for A. suum and T. suis were higher in growing and finishing pigs, whereas they were higher for Oesophagostomum spp. in finishing pigs and sows. Prevalence and abundance with A. suum eggs in feces were higher in organic certified farms, whereas abundance of Oesophagostomum spp. and T. suis was lower than those in alternative farms. Fewer eggs were recovered from soils than bedding samples, but their presence in both substrates confirmed that dispersal stages occur in farms. Overall, our results indicate that intestinal parasite infection across organic and alternative swine farms in the USA is common, and not surprising given that few options to control infection within organic regulations are available.

Feeding Management and Albendazole Pharmacokinetics in Pigs

Albendazole (ABZ) is a methylcarbamate benzimidazole anthelmintic used to control gastrointestinal parasites in several animal species and humans. The type of diet has been identified as a major determinant for ABZ pharmacokinetics in different animal species and humans. The work described here assesses the pattern of the absorption and the systemic availability of ABZ and its metabolites after its oral administration to pigs under different feed management plans. Eighteen pigs (5 months old, local ecotype breeds) were distributed into three experimental groups. In the fasting group, the animals fasted for 8 h prior to treatment. In the pellet + oil and pellet groups, the animals were fed ad libitum with a commercial pelleted-based diet with or without the addition of soya oil. An ABZ suspension was orally administered at 10 mg/kg. Blood samples were taken over the 48 h post-treatment. The plasma samples were analyzed by HPLC. Under the described experimental conditions, the ingestion of the pellet-based diet with or without the soya oil before ABZ treatment did not significantly (p < 0.05) modify the plasma disposition kinetics of the ABZ sulfoxide (ABZSO, the main ABZ metabolite) compared to that observed in the fasting pigs. Both ABZ metabolites (ABZSO and ABZ sulphone) reached similar peak concentrations and systemic exposures in all the experimental groups regardless of the feeding management. However, the addition of oil to the pelleted food enhanced the pattern of ABZ absorption, which was reflected in the higher (p < 0.05) concentration profiles of the active ABZSO metabolite measured between 12 and 48 h post-treatment compared to the pigs fed with the pelleted food alone. Although this effect may not be therapeutically relevant after ABZ administration as a single oral dose, the overall impact of the type and feeding conditions when ABZ is supplemented with food for several days should be cautiously evaluated.

Seroprevalence of Ascaris suum compared to milk spot prevalence at slaughter in Italian fattening pigs

Ascaris suum is one of the most important parasites of pigs. Apart from liver condemnation due to lesions caused by migrating larvae ("milk spots"), A. suum infections can compromise weight gain, feed conversion efficacy, as well as meat quality. The true prevalence of infection depends on the diagnostic test used and is often underestimated. We compared liver inspection at slaughter with serology, based on the recognition of a purified A. suum haemoglobin or complete homogenate of the 3rd stage larvae isolated from lungs, in nine pig farms in northern Italy. Liver lesions were found on all farms with prevalence ranging from 3.8% to 98.3%. All farms were also positive for circulating antibodies against As-Hb and As-Lung-L3, with prevalence among pigs on each farm ranging from 36.4-100% and 54.5-100%, respectively. Seroprevalence was consistently higher when compared to the prevalence of milk spots at slaughter. The higher sensitivity of the ELISA tests combined with their ease of use makes them an interesting tool to evaluate A. suum infection levels.

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.

Comparison of coproprevalence and seroprevalence to guide decision-making in national soil-transmitted helminthiasis control programs: Ethiopia as a case study

BACKGROUND

WHO recommends periodical assessment of the prevalence of any soil-transmitted helminth (STH) infections to adapt the frequency of mass drug administration targeting STHs. Today, detection of eggs in stool smears (Kato-Katz thick smear) remains the diagnostic standard. However, stool examination (coprology) has important operational drawbacks and impedes integrated surveys of multiple neglected tropical diseases. Therefore, the aim of the present study was to assess the potential of applying serology instead of coprology in STH control program decision-making.

METHODOLOGY

An antibody-ELISA based on extract of Ascaris lung stage larvae (AsLungL3-ELISA) was applied in ongoing monitoring activities of the Ethiopian national control program against schistosomiasis and soil-transmitted helminthiasis. Blood and stool samples were collected from over 6,700 students (median age: 11) from 63 schools in 33 woredas (districts) across the country. Stool samples of two consecutive days were analyzed applying duplicate Kato-Katz thick smear.

PRINCIPAL FINDINGS

On woreda level, qualitative (seroprevalence) and quantitative (mean optical density ratio) serology results were highly correlated, and hence seroprevalence was chosen as parameter. For 85% of the woredas, prevalence based on serology was higher than those based on coprology. The results suggested cross-reactivity of the AsLungL3-ELISA with Trichuris. When extrapolating the WHO coproprevalence thresholds, there was a moderate agreement (weighted κ = 0.43) in program decision-making. Using the same threshold values would predominantly lead to a higher frequency of drug administration.

SIGNIFICANCE

This is the first time that serology for soil-transmitted helminthiasis is applied on such large scale, thereby embedded in a control program context. The results underscore that serology holds promise as a tool to monitor STH control programs. Further research should focus on the optimization of the diagnostic assay and the refinement of serology-specific program decision-making thresholds.

Whipworm secretions and their roles in host-parasite interactions

Whipworm (Trichuris) is a genus of roundworms that causes gastrointestinal infections in humans and animals. Of particular interest are T. trichiura, the causative agent of human trichuriasis, a neglected tropical disease that affects 477 million people worldwide, and T. suis, the pig whipworm species, responsible for growth stunting and economic losses within the agricultural industry. The naturally occurring mouse whipworm, T. muris, has been used for decades as a model for trichuriasis, yielding knowledge on the biology of these parasites and the host response to infection. Ex vivo culture of T. muris (and to some extent, T. suis) has provided insight into the composition of the excretory/secretory (E/S) products released by worms, which include a myriad of proteins, RNAs, lipids, glycans, metabolites and extracellular vesicles. T. muris E/S has formed the basis of the search for whipworm vaccine candidates, while the immunomodulatory potential of T. suis and T. muris secretions has been investigated with the aim of improving our understanding of how these parasites modulate host immunity, as well as identifying immunomodulatory candidates with therapeutic potential in the context of inflammatory diseases. This article will review the various components found within Trichuris E/S, their potential as vaccine candidates and their immunomodulatory properties.

Serological Assessment of Ascaris suum Exposure in Greek Pig Farms and Associated Risk Factors Including Lawsonia intracellularis

The effects of nematodes and bacteria on intestinal health are of primary importance in modern swine production. The aim of the present study was to assess the seropositivity status of Ascaris suum infection in fatteners in intensive swine farms in Greece and address possible risk factors, including Lawsonia intracellularis as a predisposing factor to swine ascariosis. In total, 360 blood serum samples from pigs in the late fattening period, from 24 Greek swine farrow-to-finish farms (15 samples/farm) were collected and tested with Svanovir® A. suum antibody ELISA and Ileitis antibody ELISA. The results demonstrated 34.4% seropositive samples for A. suum and 42.2% for L. intracellularis. The analysis of predisposing risk factors suggested that the frequency of application of anthelminthic treatment to sows more than two times per year was significantly associated with the lower likelihood of A. suum infection, whereas a greater likelihood of A. suum infection was observed in pigs with concurrent L. intracellularis exposure. The results highlight the importance of proper anthelminthic metaphylaxis of the breeding stock, as well as the likely outcome of concurrent exposure to two intestinal pathogens in pigs, implying a possible association between intestinal nematodes and bacteria in swine.

Assessing the impact of Ascariasis and Trichuriasis on weight gain using a porcine model

Background

Infections with Ascaris lumbricoides and Trichuris trichiura remain significant contributors to the global burden of neglected tropical diseases. Infection may in particular affect child development as they are more likely to be infected with T. trichiura and/or A. lumbricoides and to carry higher worm burdens than adults. Whilst the impact of heavy infections are clear, the effects of moderate infection intensities on the growth and development of children remain elusive. Field studies are confounded by a lack of knowledge of infection history, nutritional status, presence of co-infections and levels of exposure to infective eggs. Therefore, animal models are required. Given the physiological similarities between humans and pigs but also between the helminths that infect them; A. suum and T. suis, growing pigs provide an excellent model to investigate the direct effects of Ascaris spp. and Trichuris spp. on weight gain.

Methods and results

We employed a trickle infection protocol to mimic natural co-infection to assess the effect of infection intensity, determined by worm count (A. suum) or eggs per gram of faeces (A. suum and T. suis), on weight gain in a large pig population (n = 195) with variable genetic susceptibility. Pig body weights were assessed over 14 weeks. Using a post-hoc statistical approach, we found a negative association between weight gain and T. suis infection. For A. suum, this association was not significant after adjusting for other covariates in a multivariable analysis. Estimates from generalized linear mixed effects models indicated that a 1 kg increase in weight gain was associated with 4.4% (p = 0.00217) decrease in T. suis EPG and a 2.8% (p = 0.02297) or 2.2% (p = 0.0488) decrease in A. suum EPG or burden, respectively.

Conclusions

Overall this study has demonstrated a negative association between STH and weight gain in growing pigs but also that T. suis infection may be more detrimental that A. suum on growth.

Infections with the roundworm, Ascaris lumbricoides and the whipworm Trichuris trichiura are estimated to affect over 800 and 400 million people, respectively. Infections are most common in children and whilst very heavy infections present clear pathology it is less clear what effect more moderate infection have on the growth and development of children. Attempts to quantify the detrimental effects in humans have been inconclusive to date due to multiple confounding variables. Therefore, animal models are required. Pigs are natural hosts to two very closely related helminths; A. suum and T. suis and therefore we have investigated the effects of infection on growing pigs. This study has identified an association of infection levels with both helminths with reduced weight gain but also that whipworm infection may be more detrimental to weight gain than giant roundworm infection. Given the overall high prevalence of A. lumbricoides and difficulties in successfully clearing whipworm infections (multiple doses of anthelminthic are required), this work highlights the importance of drug administration programs targeted to clear these infections in children.

On the Infectious Causes of Neonatal Piglet Diarrhoea—A Review

The aim of this paper is to review current knowledge on the relationship between presumptive infectious agents and neonatal porcine diarrhoea (NPD). The literature provides information on the rationale for this causation, including the first mention, main understandings gained with respect to, e.g., pathogenesis, and the knowledge to date on the specific relationships. Further, surveys on the presence and relative importance of these pathogens in NPD are included and the methodology used to identify the causation are discussed.

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.

The Use of MALDI-TOF MS as a Diagnostic Tool for Adult Trichuris Species

Trichuriasis is considered a neglected tropical disease, being the second most common helminthiasis in humans. Detection of Trichuris in routine diagnosis is usually done by microscopic detection of eggs in fecal samples. Other molecular analyses are more reliable and could be used, but these analyses are not routinely available in clinical microbiology laboratories. The use of matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) mass spectrometry (MS) is increasing since the last decades due to its recent evidence as a potential role for reliable identification of microorganisms and a few nematodes. But, for parasites detection, normalized protocols and the acquisition and introduction of new species to the database are required. We carried out a preliminary study confirming the usefulness of MALDI-TOF MS for the rapid and reliable identification of Trichuris suis used as control and the creation of an internal database. To create main spectra profiles (MSPs), the different parts of five whipworms (esophagus and intestine) were used, developing different tests to verify the repeatability and reproducibility of the spectra. Thus, to validate the new internal database, 20 whipworms, separating the esophagus and intestine, were used, of which 100% were accurately identified as T. suis, but could not distinguish between both parts of the worm. Log score values ranged between 1.84 and 2.36, meaning a high-quality identification. The results confirmed that MALDI-TOF MS was able to identify Trichuris species. Additionally, a MALDI-TOF MS profile of T. suis proteome was carried out to develop the first internal database of spectra for the diagnosis of trichuriasis and other Trichuris spp.

Dietary proanthocyanidins promote localized antioxidant responses in porcine pulmonary and gastrointestinal tissues during Ascaris suum-induced type 2 inflammation

Proanthocyanidins (PAC) are dietary polyphenols with putative anti-inflammatory and immunomodulatory effects. However, whether dietary PAC can regulate type-2 immune function and inflammation at mucosal surfaces remains unclear. Here, we investigated if diets supplemented with purified PAC modulated pulmonary and intestinal mucosal immune responses during infection with the helminth parasite Ascaris suum in pigs. A. suum infection induced a type-2 biased immune response in lung and intestinal tissues, characterized by pulmonary granulocytosis, increased Th2/Th1 T cell ratios in tracheal-bronchial lymph nodes, intestinal eosinophilia, and modulation of genes involved in mucosal barrier function and immunity. Whilst PAC had only minor effects on pulmonary immune responses, RNA-sequencing of intestinal tissues revealed that dietary PAC significantly enhanced transcriptional responses related to immune function and antioxidant responses in the gut of both naïve and A. suum-infected animals. A. suum infection and dietary PAC induced distinct changes in gut microbiota composition, primarily in the jejunum and colon, respectively. Notably, PAC consumption substantially increased the abundance of Limosilactobacillus reuteri. In vitro experiments with porcine macrophages and intestinal epithelial cells supported a role for both PAC polymers and PAC-derived microbial metabolites in regulating oxidative stress responses in host tissues. Thus, dietary PAC may have distinct beneficial effects on intestinal health during infection with mucosal pathogens, while having a limited activity to modulate naturally-induced type-2 pulmonary inflammation. Our results shed further light on the mechanisms underlying the health-promoting properties of PAC-rich foods, and may aid in the design of novel dietary supplements to regulate mucosal inflammatory responses in the gastrointestinal tract.

Anthelmintic efficacy of oxibendazole against gastrointestinal nematodes in swine

In swine production, parasites, especially gastrointestinal helminths, generate considerable economic losses. Therefore, effective control measures, such as the use of the correct anthelmintics, are of paramount importance for maintaining profitability. The aim of the present study was to evaluate the efficacy of the anthelmintic oxibendazole, administered orally, in pigs (non-industrial) naturally infected with gastrointestinal nematodes. To that end, we selected 18 pigs naturally parasitized by gastrointestinal nematodes, as determined by examination of fecal samples (eggs per gram (EPG > 500) of feces), and divided them into two groups: treated (with a 10-day course of oxibendazole) and control (untreated). After the treatment period, the animals were euthanized. During necropsy, the helminths in the gastrointestinal tract were identified and quantified. The species identified were, in order of occurrence, Ascaris suum, Trichuris suis, Oesophagostomum dentatum, and Hyostrongylus rubidus. In Brazilian swine herds, traditional (non-industrial) production systems can favor the transmission of helminths. We found that treatment with oxibendazole was 100% effective against A. suum and H. rubidus, whereas it was 99.65% effective against O. dentatum and 99.20% effective against T. suis, significantly reducing helminth counts (P < 0.01 for all). We conclude that oxibendazole is effective in controlling the main helminths in swine.

Local and Systemic T Cell Immunity in Fighting Pig Viral and Bacterial Infections

T cells are an essential component of the adaptive immune system. Over the last 15 years, a constantly growing toolbox with which to study T cell biology in pigs has allowed detailed investigations on these cells in various viral and bacterial infections. This review provides an overview on porcine CD4, CD8, and γδ T cells and the current knowledge on the differentiation of these cells following antigen encounter. Where available, the responses of these cells to viral infections like porcine reproductive and respiratory syndrome virus, classical swine fever virus, swine influenza A virus, and African swine fever virus are outlined. In addition, knowledge on the porcine T cell response to bacterial infections like Actinobacillus pleuropneumoniae and Salmonella Typhimurium is reviewed. For CD4 T cells, the response to the outlined infections is reflected toward the Th1/Th2/Th17/Tfh/Treg paradigm for functional differentiation. Expected final online publication date for the Annual Review of Animal Biosciences, Volume 10 is February 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Comparison of different detection methods for Ascaris suum infection on Austrian swine farms

Background

Ascaris suum, the large roundworm of pigs, is one of the economically most important pig parasites worldwide. In Austria it is commonly diagnosed by monitoring livers for milk spots at the slaughterhouse and intravital diagnosis (flotation for detection of fecal egg shedding). Recently, serological diagnosis based on the detection of specific antibodies with an ELISA (SERASCA®) with high sensitivity has been developed. To introduce and evaluate serology for A. suum screening in Austrian pigs, blood (for serology) (n = 177) and feces (for copromicroscopy) (n = 177) were taken from randomly selected slaughter pig batches from 18 farms at a slaughterhouse in Lower Austria. In addition, livers presented at slaughter (n = 844; max. 70/farm) were evaluated for milk spots.

Results

Overall, 19% of the livers were milk spot-positive (22% of those with complete diagnostic evaluations). Thirteen percent of the fecal samples contained A. suum eggs, while 69% of the blood samples were serologically positive. Despite we did not determine the sensitivity of the ELISA specifically, results ouf our study confirmed the high sensitivity of the ELISA, which was claimed by the manufacturer prior to our work (sensitivity: liver assessment: 23.5–27.0%; copromicroscopy: 8.5–9.0%; ELISA: 99.5%), and a high percentage of A. suum infections that remained undetected by standard liver assessment.

Conclusions

This suggests that the current method of roundworm diagnostics is insufficient and antibody detection at the end of the fattening period should be established as the standard procedure.

Seroprevalence of Taenia solium and Trichinella spiralis among Humans and Pigs in Ghana

In this study, the seroprevalence of the intestinal worms Taenia solium and Trichinella spiralis in humans and pigs was assessed. A cross-sectional serological study design was performed. Blood samples were collected from 322 humans and 245 pigs used in the study. These were tested for markers of antibodies for Taenia solium and Trichinella spp. Demographic data such as sex, age, education, pig farming practices, and water source used were also obtained. An overall seroprevalence of 3.1% was recorded for Taenia solium in humans. There was also a statistical association between pig management system employed by pig farmers and seropositivity to Taenia solium (p = 0.005). Factors such as mode of waste disposal (p = 0.003) and water source used statistically correlated with Taenia solium seroprevalence among humans. For the pig samples, a Taenia solium seroprevalence of 24.9% was recorded. All the pig samples which tested positive for Taenia solium were reared on the free-ranged system. This study also recorded a seroprevalence of 0.31% for Trichinella spp. for humans and a seroprevalence of 4.5% for Trichinella spp. for pigs. Again, all the samples that showed serological evidence of Trichinella spp. among pigs came from those pigs which were raised on the free-ranged system. Proper pig management practice is a very important tool for controlling these intestinal parasites in both humans and animals. This study recommends public health education among the general public and good pig farming practices.

Globocephalus urosubulatus (Alessandrini, 1909) (Nematoda: Ancylostomatidae) in Brazil: a morphological revisitation

Helminthiasis occurs frequently in wild or domestic pigs in the most varied environments or production systems; however, the literature includes few taxonomic studies for the purpose of expanding this knowledge about the parasitic diversity in these animals. Thus, in order to expand this knowledge regarding parasitic diversity in these animals, the present study reports the occurrence and redescribes Globocephalus urosubulatus infecting domestic pigs in the state of Pará, Brazil, using microscopy. Four hundred and ten specimens of Sus scrofa intestinal nematodes were collected extensively in the municipality of Moju, northeastern mesoregion of Pará and observed under light and scanning electron microscopy. Based on morphological characteristics, the nematodes were identified as G. urosubulatus, and new morphological data were added by light microscopy and scanning electron microscopy for the diagnosis of this parasite.

Etiology of Colitis-Complex Diarrhea in Growing Pigs: A Review

Simple Summary

Diarrhea in growing pigs is a challenge for the pig industry since it is associated with reduced animal welfare, retarded growth, increased feed conversion ratio, and is often treated with antibiotics. One of the major causes of diarrhea in the growing period is large intestinal inflammation, often referred to as colitis. The exact causes of colitis-complex diarrhea are still to be understood, but dietary factors and/or pathogens have been recognized as the major factors in developing colitis-complex diarrhea. In this review, a thorough picture of pathogens, dietary factors, and a number of possible biomarkers related to colitis-complex diarrhea is presented.

Abstract

Colitis-complex diarrhea (CCD) in pigs can be defined as a type of diarrhea, which is associated with colonic inflammation and disrupted colonic gut barrier functionality in growing pigs (4–16 weeks post-weaning). It is a challenge for the pig industry as it is associated with the high use of antibiotics, reduced animal welfare, and depressed growth rate. The exact etiology of CCD is still unclear; however, pathogens including Brachyspira (B.) hyodysenteriae, B. pilosicoli, and swine whipworms such as Trichuris (T.) suis have been involved in specific colitis (SC). In the absence of specific pathogens, dietary factors, such as high levels of protein, pelleted feedstuffs, and lack of sufficient antioxidants, can result in non-specific colitis (NSC). On the other hand, supplement of polyunsaturated fatty acids (PUFA) and polyphenols, sufficient supply of essential amino acids (e.g., threonine, cysteine, and proline), short-chain fatty acids (SCFA; especially butyrate), and resistant starch have shown to confer preventing/ameliorating effects on CCD. Different putative biomarkers associated with CCD have been presented. It is anticipated that a comprehensive picture of the possible causes of CCD and potential dietary interventions could cast light on the direction of future studies aimed at developing preventive and curative strategies against CCD in growing pigs.

First isolation of Trichuris from wild blue sheep (Pseudois nayaur) in the Helan Mountains, China

Four adult female worms of Trichuris were isolated from an individual of the wild blue sheep (Pseudois nayaur) inhabiting the Helan Mountains, China, during an epidemiological survey of this wild ruminant. Although there were some differences among the worms in posterior end (rectum) morphology and egg shape, little information regarding species status could be inferred from their morphology. Phylogenetic trees were constructed based on sequences of the ITS1 segment of ribosomal RNA (rRNA), and the sequences of the four Trichuris specimens from wild blue sheep were divided into two distinct lineages (Clade A and Clade B). The two specimens in Clade A were named Genotype I, and had the closest relationship with Trichuris skrjabini; the two specimens in Clade B were named Genotype II and had the closest genetic relationship with a previously described Trichuris sp. In the two Trichuris genotypes identified in the present study, the 18S fragments (261 to 262 bp) of the newly obtained sequences were found to be highly conserved, with merely one insert mutation of a single nucleotide present. The genetic distance based on ITS1 between members of Clade A, composed of two T. skrjabini individuals and two Genotype I individuals, ranged from 0 to 0.0034. These distances are within the intraspecies variation of Trichuris (0-0.0272), suggesting that the Genotype I individuals infesting the wild blue sheep were T. skrjabini. In Clade B, the newly obtained sequences clustered with Trichuris sp. specimens isolated from ruminants (sheep and black goat) with strong support, and the genetic distance ranged from 0.0068 to 0.017, which is also within the intraspecies variation of Trichuris (0-0.0272). However, the genetic distances between the Clade A and Clade B were 0.0442 to 0.0578, which are higher than the intraspecies distances in Trichuris but lower than the interspecies distances (0.102-0.5078). These results implied that Clade A and Clade B most likely represent two subpopulations of T. skrjabini; however, the possibility that Clade A is T. skrjabini and Clade B is a Candidatus Trichuris could not be excluded.

Animal health beyond the single disease approach - A role for veterinary herd health management in low-income countries?

In order to identify and evaluate health related constraints faced by Ugandan pig farmers, a veterinary herd health management approach (VHHM) was applied in 20 randomly selected pig farms in the Lira district, Uganda. Regular herd visits were conducted between July 2018 and June 2019, using e.g. interviews, observations, clinical examinations and laboratory analyzes to gather qualitative and quantitative data on relevant aspects of the production. The pig farmers kept on average 18.6 pigs, including 2.6 sows/year. The production figures varied considerably but were generally poor. The sows produced 1.6 litters/year and 8.2 piglets born alive per litter, the average daily gain was 101 g/day, and the mortality in growers was 9.7%. Four major constraints were identified; poor nutrition, infectious diseases, inferior biosecurity, and poor reproductive management. The quantity and quality of feed was suboptimal. Endo- and ectoparasites were very common, causing diarrhea, bronchitis, pneumonia, skin lesions and pruritus. Post-weaning diarrhea associated with enterotoxigenic Escherichia coli was important in the two largest herds, and parvoviral antibodies were found in seven herds, two experiencing problems with mummified fetuses. Biosecurity practices were insufficient and inconsistent, with free-ranging pigs and the use of village boars being the major risks. Reproductive figures were affected by poor estrus detection and service management. Overall, farmers lacked important knowledge on good management practices. In conclusion, the VHHM identified several important constraints that should be addressed in order to increase the productivity of Ugandan pig herds.

Emerging interactions between diet, gastrointestinal helminth infection, and the gut microbiota in livestock

Increasing evidence suggests that nutritional manipulation of the commensal gut microbiota (GM) may play a key role in maintaining animal health and production in an era of reduced antimicrobial usage. Gastrointestinal helminth infections impose a considerable burden on animal performance, and recent studies suggest that infection may substantially alter the composition and function of the GM. Here, we discuss the potential interactions between different bioactive dietary components (prebiotics, probiotics and phytonutrients) and helminth infection on the GM in livestock. A number of recent studies suggest that host diet can strongly influence the nature of the helminth-GM interaction. Nutritional manipulation of the GM may thus impact helminth infection, and conversely infection may also influence how the GM responds to dietary interventions. Moreover, a dynamic interaction exists between helminths, the GM, intestinal immune responses, and inflammation. Deciphering the mechanisms underlying the diet-GM-helminth axis will likely inform future helminth control strategies, as well as having implications for how health-promoting feed additives, such as probiotics, can play a role in sustainable animal production.

Potential modulating effect of the Ascaris suum nicotinic acetylcholine receptor (nAChR) by compounds GSK575594A, diazepam and flumazenil discovered by structure-based virtual screening approach

Parasitic infections are a widespread health problem and research of novel anthelmintic compounds is of the utmost importance. In this study we performed a virtual screening campaign by coupling ligand-based pharmacophore, homology modeling and molecular docking. The virtual screening campaign was conducted using a joined pool of the Drugbank database and a library of purchasable compounds in order to identify drug like compounds with similar pharmacological activity. Our aim was to identify compounds with a potential antihelmintic modulatory effect on nicotinic acetylcholine receptors (nAChR). We derived a 3D pharmacophore model based on the chemical features of known Ascaris suum nAChR modulators. To evaluate the in silico predictions, we tested selected hit compounds in contraction assays using somatic muscle flaps of the Ascaris suum neuromuscular tissue. We tested the modulatory effects of GSK575594A, diazepam and flumazenil hit compounds on nematode contractions induced by acetyl choline (ACh). The compound GSK575594A (3 μM) increased the E_max by 21 % with the EC₅₀ dose ratio of 0.96. Diazepam (100 μM) decreased the E_max by 15 % (1.11 g to 0.95 g) with the EC₅₀ ratio of 1.42 (shifted to the left from 11.25 to 7.93). Flumazenil decreased the EC₅₀ value (from 11.22 μM to 4.88 μM) value showing dose ratio of 2.30, and increased the E_max by 4 % (from 1.54 g to 1.59 g). The observed biological activity was rationalized by molecular docking calculations. Docking scores were calculated against several binding sites within the Ascaris suum homology model. We constructed the homology model using the ACR-16 subunit sequence. The compound GSK575594A showed strong affinity for the intersubunit allosteric binding site within the nAChR transmembrane domain. The binding modes of diazepam and flumazenil suggest that these compounds have a comparable affinity for orthosteric and allosteric nAChR binding sites. The selected hit compounds displayed potential for further optimization as lead compounds. Therefore, such compounds may be useful in neutralizing the growing resistance of parasites to drugs, either alone or in combination with existing conventional anthelmintics.

A case of eagle fern (Pteridium aquilinum) poisoning on a pig farm

Background

Free-range pig farming represents a minor proportion of pig production in France but is attracting an increasing number of farmers because of societal expectations and the opportunity to use pasture-grazed forage. However, this type of farming faces several challenges, including biosecurity, parasitic management, and contact with wild fauna and pathogenic flora.

Case presentation

Two Gascon pigs raised on an outdoor fattening farm in the Hautes-Pyrenees department of France were submitted after sudden death for necropsy at the National Veterinary School of Toulouse. The pigs were of two different breeds but from the same group of 85 animals that had grazed on a 4-ha plot of land being used for grazing for the first time. Based on an in-depth interview with the farmer, the epidemiological information available, and the necropsy and histology examinations, a hypothesis of great eagle fern intoxication was proposed. Although the sample of animals available for diagnosis was small, the success of the administered therapy confirmed our diagnosis. It was recommended that in the short term, the animals be prevented access to the eagle fern by changing their pasture or removing the plants. Vitamin B1 and vitamin B6 were administered via feed as Ultra B® at 1 mL per 10 kg body weight per day for 2 days (providing 9 mg thiamine (vitamin B1) and 0.66 mg pyridoxine (vitamin B6) per kg body weight per day). Marked remission was observed, with 6 of 10 intoxicated animals with symptoms surviving (yielding a therapeutic success rate over 50%), but the therapy did not compensate for the loss of initial body condition. In total, of the 85 animals in the group after intoxication, 6 died, and 6 recovered.

Conclusions

The significance of this report lies in the scarcity of eagle fern intoxication cases reported in the literature, though such intoxication may become a significant problem as the development of outdoor rearing continues. Thus, eagle fern intoxication should be included in the differential diagnosis of nervous system symptoms in swine. The case also emphasizes the importance of anamnesis and discussion with the farmer as an essential step to guide diagnosis.

Health and welfare in organic livestock production systems—a systematic mapping of current knowledge

This review aimed to systematically map and summarize the status of animal health and welfare in organic production. The prevalence of diseases and behavioural effects in organic dairy cow, beef cattle, sheep, pig, laying hen and broiler chicken were discussed in the context of the organic values and current knowledge on animal health and welfare. In total 166 peer-reviewed scientific publications between 2008 and 2020 were included. No strong evidence for neither inferior nor distinctly higher animal welfare in organic compared with conventional production could be supported. The welfare status of organic livestock is in general good in relation to the OIE definition of animal health and welfare. However, organic systems are still facing several challenges related to animal health and the arising of goal conflicts due to management and practical implications. Greater possibilities to perform species-specific behaviours in organic production systems, however, indicate that the organic standards offer a good framework for high animal welfare management. For organic dairy farmers, the main health problems are similar to those of non-organic farms; especially mastitis and lameness need improvement. Parasites, together with mastitis and lamb mortality, are important welfare issues in organic sheep production. Piglet mortality, leg problems, parasite load and increasing respiratory problems are of major relevance in organic pig production. For organic laying hens, major health challenges relate to feather pecking and cannibalism, parasites and possibilities to express species-specific behaviours. For organic broilers, dermatitis of footpads, hocks and breast are reported as main health issues.

Evidence for mitochondrial pseudogenes (numts) as a source of contamination in the phylogeny of human whipworms

Trichuris trichiura and T. suis are whipworms of humans and pigs, respectively, but it has recently been suggested that humans may be infected with multiple genotypes or species of Trichuris and cross-infection with Trichuris of pig origin has also been reported. In addition, the species status of Trichuris in non-human primates is unsettled and it is unknown how many whipworm species we share with other primates. Herein, we inferred the phylogeny of Trichuris collected from human, baboon and pig based on nuclear (18S and beta-tubulin) and mitochondrial (cox1) genes and evaluated the use of three PCR linked restriction fragment length polymorphism (PCR-RFLP) to identify worms. We found that all baboon worms clustered with human worms and that all these primate worms are different from T. suis. In general, there was an agreement between the phylogeny established based on the nuclear and mtDNA genes. However, we found evidence for non-targeted cox1 gene amplification for a subset of the human worms and suggest the presence of mitochondrial pseudogenes (numts) of pig cox1 gene in the human Trichuris genome. In conclusion, phylogenetic characterization of human whipworm based on the cox1 gene alone may be problematic without suitable preceded measures to avoid the numts amplification.

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.

Prevalence and Risk Factors of Intestinal Parasite Infections in Greek Swine Farrow-To-Finish Farms

Intestinal parasites, helminths, and protozoa challenge health and welfare of pigs and deteriorate the sustainability of swine farms leading to monetary losses. A multicentric survey was conducted for approximately one year. Overall, 1150 fecal samples were collected from eight intensive farms in Greece at regular intervals and examined by flotation and Ziehl-Neelsen techniques. Age, season, and time of last recorded antiparasitic treatment were assessed as possible risk factors using binary regression models. The overall prevalence of intestinal parasitism in pigs was 44.7%. The most frequently detected parasites in the studied population were the protozoa Balantidium coli (37.8%), followed by Entamoeba spp. (8.3%), Cystoisospora suis (6.0%), and the nematodes Ascaris suum (3.7%), Trichuris suis (2.5%), and Oesophagostomum spp. (1.4%). Distribution of intestinal parasites in different age groups was as expected. In autumn, the prevalence of Balantidium coli infection enhanced whereas the prevalence of Entamoeba spp. and Cystoisospora suis infections increased in spring. Time of last recorded antiparasitic treatment influenced Balantidium coli and Trichuris suis infection levels. Our results demonstrated that swine intestinal parasitism in intensive farms of Greece seems to be relatively common and highlighted the importance of proper laboratory examinations, as well as the need for tailored made control programs.

Real-time detection and identification of nematode eggs genus and species through optical imaging

Nematode eggs are pervasive pathogens that infect billions of people and livestock every year. Adult parasitic nematode worms can be distinguished based on their size and morphology. However, their eggs, particularly their species Ascaris lumbricoides and Ascaris suum cannot be identified from each other. Identifying eggs of helminths from wastewater and sludge is important from a public health perspective to minimize the spread of Ascaris infections. Numerous methods exist for nematode identification, from a morphological-based approach to high throughput sequencing technology. However, these techniques are not consistent and often laborious and time-consuming. In this study, we demonstrate that non-invasive real-time identification of eggs is possible based on their intrinsic fluorescence. Using confocal microscopy, we investigate the autofluorescence properties of five species of nematode eggs and observe clear differences between genus and for the first time their species in sludge samples. This non-invasive imaging technique could lead to better understanding of these species and may assist in early control of diseases.

Carvacrol acts as a potent selective antagonist of different types of nicotinic acetylcholine receptors and enhances the effect of monepantel in the parasitic nematode Ascaris suum

The neuromuscular system of parasitic nematodes has proven to be an efficient pharmacological target for antihelmintics. Some of the most frequently used antiparasitic drugs are agonists or antagonists of nicotinic acetylcholine receptors (nAChRs). The antinematodal mechanism of action of carvacrol involves the inhibition of parasite muscle contraction. We have examined the interaction of carvacrol with antinematodal drugs that are agonists of different subtypes of nAChRs and monepantel, which is a non-competitive antagonist of this receptor in A. suum. Additionally, we investigated the effect of carvacrol on the muscle type of nAChRs in the mammalian host. As orthosteric agonists of nAChR, pyrantel, morantel and befinijum lead to dose-dependent contractions of the neuromuscular preparation of Ascaris suum. Carvacrol 100 μM decreased the E_max of pyrantel, morantel and bephenium by 29%, 39% and 12 %, 39 % and 12 % respectively. The EC₅₀ ratio was 3.43, 2.95 and 2.47 for pyrantel, morantel and bephinium, respectively. Carvacrol 300 u μM reduces the E_max of pyrantel, morantel and bephenium by 71%, 80% and 75 %, 80 % and 75 % respectively. The EC₅₀ ratio for pyrantel, morantel and bephenium was 3.88, 3.19 and 4.83 respectively. Furthermore, carvacrol enhances the inhibitory effect of monepantel on A. suum contractions, which may have an effective clinical application. On the other hand, tested concentrations of carvacrol did not significantly affect the EFS-induced contractions of the rat diaphragm, indicating a lack of interaction with the postsynaptic nAChR at the muscle end plate in mammals, but the highest concentration (300 μM) caused a clear tetanic fade. Carvacrol exhibited a time and dose-dependent effect on the Rota-rod performances of rats with a high value of the ED₅₀ (421.6 mg/kg). In our research, carvacrol dominantly exhibited characteristics of a non-competitive antagonist of nAChR in A. suum, and enhances the inhibitory effect of monepantel. The combination of monepantel and carvacrol may be clinically very effective, and the carvacrol molecule itself can be used as a promising platform for the development of new anthelmintic drugs.

Diversity and prevalence of gastrointestinal parasites in farmed pigs in Southeast Gabon, Central Africa

Background and Aim

Gastrointestinal infestations caused by intestinal parasites are the most important diseases and the most common in pigs in the tropics. These parasites are often associated with a huge economic loss. This study aimed to assess the diversity and prevalence of gastrointestinal parasites in farmed pigs from Haut-Ogooue Province, in South East Gabon.

Materials and Methods

From March 2018 to July 2018, 156 samples of pig feces collected from nine different farms were analyzed under light microscopy. The identification of eggs, cysts, and oocysts in fecal samples was done using two qualitative techniques: Flotation and sedimentation.

Results

After examination, the results obtained revealed an overall infestation level of 98.7% (154/156). We found ten parasite types with infestation levels that varied from species: Balantidium coli (120/156), Oesophagostomum spp. (100/156), Isospora suis (102/156), Ancylostoma spp. (17/156), Trichostrongylus spp. (28/156), Hyostrongylus spp. (13/156), Strongyloides spp. (7/156), Ascaris suum (8/156), Globocephalus spp. (1/156), and spirurida (1/156). The study of risk factors revealed that factors such as sex, age, and physiological condition may influence the diversity and level of infestation of animals by gastrointestinal parasites.

Conclusion

For better prevention of parasitism in these farms, it would be interesting to implement health monitoring and to ensure good hygiene. Finally, further studies would be needed to better evaluate the distribution of these parasites in Gabon and the involvement of these animals in the transmission cycle of parasitic zoonoses.

Fenbendazole induces apoptosis of porcine uterine luminal epithelial and trophoblast cells during early pregnancy

Fenbendazole, is an effective benzimidazole anthelmintic that prevents parasite infection in both human and veterinary health care. Although the well-known and effect of benzimidazole was recently shown to have a broad spectrum of biological abilities, such as anticancer and anti-inflammation activities, the mechanism of benzimidazole's antiproliferative effect via cell signaling pathways and its role in preimplantation has not been studied. Therefore, the purpose of this study was to determine the effects of fenbendazole on porcine trophectoderm and luminal epithelial cells. First, we investigated cell viability in response to a low dose of fenbendazole, which highly inhibited cell proliferation. In addition, we investigated apoptotic molecules in the mitochondria, imbalanced intracellular calcium homeostasis, and the expression of some genes involved in apoptosis to explain the decrease in proliferation. Finally, we examined the intracellular mechanisms of fenbendazole by measuring the extracellular signal-regulated kinase, PI3K/AKT, and c-Jun N-terminal kinase signaling proteins by western blot analysis. Our findings suggest that fenbendazole functions as an effective anti-proliferative molecule that induces critical apoptosis in the porcine trophectoderm and uterine luminal epithelial cells by disrupting the mitochondria membrane potential during early pregnancy.

Genetic diversity of Ascaris spp. infecting humans and pigs in distinct Brazilian regions, as revealed by mitochondrial DNA

In this study, we assessed the genetic diversity of Ascaris lumbricoides / Ascaris suum circulating in humans and pigs, exploring potential zoonotic cycles in endemic areas in Brazil. We carried out cross-sectional surveys in four municipalities: Santa Isabel do Rio Negro (SIRN-AM) (n = 328); Nossa Senhora de Nazaré (NSN-PI) and Teresina (TER-PI) (n = 605 and n = 297, respectively); and Cachoeiras de Macacu (CAM-RJ) (n = 543). We also studied 61 fecal samples/adult worms obtained from pigs (n = 53 in NSN-PI and n = 8 in TER-PI). A ~450 bp fragment of the Ascaris cytochrome c oxidase subunit 1 (cox1) and ~400 bp of the NADH dehydrogenase subunit 1 (nad1) were amplified and sequenced. Maximum-likelihood (ML) tree and Median-joining (MJ) haplotype network analyses were performed. We also performed scanning electron micrographs of adult specimens. Positivity rates were 93/328 (28.4%) in SIRN-AM, 6/297 (2.0%) in TER-PI, 0/605 (0%) in NSN-PI, and 6/543 (1.1%) in CAM-RJ. In NSN-PI it reached 11/53 (20.7%) in pigs. The MJ network based on cox1 locus (383 bp) revealed three main clusters, one centered around haplotypes H01/H28/H32 and the other around H07/H11. The cox1 haplotypes had a heterogeneous distribution, showing no pattern by geographic region, and high haplotype diversity. The ML trees based on cox1 and nad1 loci showed a similar topology with each other, and with the haplotype networks. Three distinct clusters were observed. Sequences of cox1 and nad1 from humans and animals were distributed throughout the tree and it was not possible to differentiate specimens of human and swine origin. Ascaris populations obtained from humans and swine in different Brazilian regions are not discriminable through the genetic markers used, which indicates the potential for zoonotic transmission and the need for better control of these infections in swine herds, mainly when created in a peridomestic environment.

Characterization of the Complete Mitochondrial Genome of a Whipworm Trichuris skrjabini (Nematoda: Trichuridae)

The complete mitochondrial (mt) genome of Trichuris skrjabini has been determined in the current study and subsequently compared with closely related species by phylogenetic analysis based on concatenated datasets of mt amino acid sequences. The whole mt genome of T. skrjabini is circular and 14,011 bp in length. It consists of a total of 37 genes including 13 protein coding genes (PCGs), two ribosomal RNA (rRNA) genes, 22 transfer RNA (tRNAs) genes, and two non-coding regions. The gene arrangement and contents were consistent with other members of the Trichuridae family including Trichuris suis, Trichuris trichiura, Trichuris ovis, and Trichuris discolor. Phylogenetic analysis based on concatenated datasets of amino acids of the 12 PCGs predicted the distinctiveness of Trichuris skrjabini as compared to other members of the Trichuridae family. Overall, our study supports the hypothesis that T. skrjabini is a distinct species. The provision of molecular data of whole mt genome of T. skrjabini delivers novel genetic markers for future studies of diagnostics, systematics, population genetics, and molecular epidemiology of T. skrjabini.

First detection of ivermectin resistance in oesophagostomum dentatum in pigs

In 2016 suspected reduced ivermectin (IVM) efficacy in Oesophagostomum species in pigs was reported in England. Following this initial report, APHA raised awareness amongst private pig veterinary practitioners of the need to monitor the efficacy of the worm control on pig units. In 2017 another veterinary practitioner highlighted a potential in-field lack of IVM efficacy in treating Oesophagostomum species in sows on another breeder-finisher unit. In this trial, the efficacy of IVM against Oesophagostomum species worms has been investigated to determine whether suspected reduced efficacy (52% reduction in mean faecal egg count 14 days post ivermectin administration) on a mixed indoor and outdoor breeder-finisher pig farm in England reflected true IVM resistance under controlled experimental conditions. On days 0 and 40 of the trial, twenty helminth-naive pigs were artificially infected per os with 5000 Oesophagostomum L3 obtained from the farm under investigation. The pigs were allocated to treatment or control groups (n = 10 per group). Treatment group pigs received IVM (0.3 mg kg body weight) by sub-cutaneous injection as per manufacturer's instructions on day 44. Control group animals were left untreated. Faecal worm egg counts were monitored throughout the trial from day 15 post infection to determine time to patency. On day 50 all pigs were euthanased to assess the worm burdens. Resistance to IVM was confirmed in Oesophagostomum dentatum based on the results of a faecal egg count reduction test (FECRT) and a controlled efficacy test (CET). Efficacy based on mean reduction in faecal egg count of IVM-treated pigs compared to untreated control pigs was 86%. Mean reduction in IVM-treated pig worm burdens was 5% against an adult worm population and 94% against an L3/L4 population. The apparent discrepancy between FECRT and CET efficacy results appears to be due to egg development and/or oviposition suppression in IVM-treated female worms. The detection of IVM resistance in Oesophagostomum species worms for the first time in UK pigs is particularly important considering the global situation where resistance to pyrantel, levamisole and benzimidazole anthelmintics in Oesophagostomum species in pigs have already been reported. The results also provide an opportunity to discuss the wider issue of anthelmintic usage and efficacy on pig farms and highlight the need for wider surveillance for the occurrence of anthelmintic resistance in pigs.

Prevalence and Phylogenetic Analyses of Trichuris suis in Pigs in Hunan Province, Subtropical China

Trichuris suis infection in pigs is ubiquitous in intensive and extensive farms, which causes potential threat to human health. The objective of this research was to investigate the prevalence of T. suis in pigs in Hunan province. Total 2,267 fresh fecal samples distributed in 28 pig farms from 7 different administrative regions (Hunan province) were evaluated for the existence of T. suis eggs using saturated NaCl floating method. The average infection rate of T. suis in pigs was 8.91% in Hunan province. To determine genetic variation of the gained T. suis isolates in the present study, the internal transcribed spacer (ITS) regions from nuclear ribosomal DNA (rDNA) of 7 T. suis isolates were cloned and analyzed. Nucleotide diversities were 1.0–3.5% and 0–3.8% for ITS-1 and ITS-2, respectively. Phylogenetic analyses indicated that all isolates collected in the present study and T. suis available in Genbank generated a monophyletic clade. The present investigation revealed high infection rates of T. suis in pigs in Hunan province, which shed light on making effective measures to prevent and control T. suis infection in pigs in Hunan province.

Derivation of the economic value of R0 for macroparasitic diseases and application to sea lice in salmon

BACKGROUND

Macroparasites, such as ticks, lice, and helminths, are a concern in livestock and aquaculture production, and can be controlled by genetic improvement of the host population. Genetic improvement should aim at reducing the rate at which parasites spread across the farmed population. This rate is determined by the basic reproduction ratio, i.e. [Formula: see text], which is the appropriate breeding goal trait. This study aims at providing a method to derive the economic value of [Formula: see text].

METHODS

Costs of a disease are the sum of production losses and expenditures on disease control. Genetic improvement of [Formula: see text] lowers the loss-expenditure frontier. Its economic effect depends on whether the management strategy is optimized or not. The economic value may be derived either from the reduction in losses with constant expenditures or from the reduction in expenditures with constant losses.

RESULTS

When [Formula: see text] ≤ 1, the economic value of a further reduction is zero because there is no risk of a major epidemic. When [Formula: see text] > 1 and management is optimized, the economic value increases with decreasing values of [Formula: see text], because both the mean number of parasites per host and frequency of treatments decrease at an increasing rate when [Formula: see text] decreases. When [Formula: see text] > 1 and management is not optimized, the economic value depends on whether genetic improvement is used for reducing expenditures or losses. For sea lice in salmon, the economic value depends on a reduction in expenditures with constant losses, and is estimated to be 0.065€/unit [Formula: see text]/kg production.

DISCUSSION

Response to selection for measures of disease prevalence cannot be predicted from quantitative genetic theory alone. Moreover, many studies fail to address the issue of whether genetic improvement results in reduced losses or expenditures. Using [Formula: see text] as the breeding goal trait, weighed by its appropriate economic value, avoids these issues.

CONCLUSION

When management is optimized, the economic value increases with decreasing values of [Formula: see text] (until the threshold of [Formula: see text], where it drops to zero). When management is not optimized, the economic value depends on whether genetic improvement is used for reduced expenditures or production losses. For sea lice in salmon, the economic value is estimated to be 0.065 €/unit [Formula: see text]/kg production.

Vaccines against Trichinella spiralis: Progress, challenges and future prospects

Trichinella spiralis, the causative agent of trichinellosis, is able to infect a wide range of carnivores and omnivores including human beings. In the past 30 years, a mass of vaccination efforts has been performed to control T. spiralis infection with the purpose of reduction in worm fecundity or decrease in muscle larval and adult burdens. Here, we summarize the development of veterinary vaccines against T. spiralis infection. During recent years, increasing numbers of new vaccine candidates have been developed on the protective immunity against T. spiralis infection in murine model. The vaccine candidates were not only selected from excretory-secretory (ES) antigens, but also from the recombinant functional proteins, such as proteases and some other antigens participated in T. spiralis intracellular processes. However, immunization with a single antigen generally revealed lower protective effects against T. spiralis infection in mice compared to that with the inactivated whole worms or crude extraction and ES productions. Future study of T. spiralis vaccines should focus on evaluation of the protective efficacy of antigens and/or ligands delivered by nanoparticles that could elicit Th2-type immune response on experimental pigs.