Interaction between Ascaris suum and Pasteurella multocida in the lungs of mice

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.

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.

The long and winding road of Ascaris larval migration: the role of mouse models

Ascaris lumbricoides and Ascaris suum are helminth parasites of humans and pigs, respectively. The life cycle of Ascaris sets it apart from the other soil-transmitted helminths because of its hepato-tracheal migration. Larval migration contributes to underestimated morbidity in humans and pigs. This migration, coupled with a lack of a murine model in which the Ascaris parasite might complete its life cycle, has undoubtedly contributed to the neglected status of the ascarid. Our knowledge of the epidemiology of adult worm infections had led us to an enhanced understanding of patterns of infection such as aggregation and predisposition; however, the mechanisms underlying these complex phenomena remain elusive. Carefully controlled experiments in defined inbred strains of mice – with enhanced recovery of larvae in tandem with measurements of cellular, histopathological and molecular processes – have greatly enhanced our knowledge of the early phase of infection, a phase crucial to the success or failure of adult worm establishment. Furthermore, the recent development of a mouse model of susceptibility and resistance, with highly consistent and diverging Ascaris larval burdens in the murine lungs, represents the extremes of the host phenotype displayed in the aggregated distribution of worms and provides an opportunity to explore the mechanistic basis that confers predisposition to light and heavy Ascaris infection. Certainly, detailed knowledge of the cellular hepatic and pulmonary responses at the molecular level can be accrued from murine models of infection and, once available, may enhance our ability to develop immunomodulatory therapies to elicit resistance to infection.

Effect of strategic deworming on Ascaris suum exposure and technical performance parameters in fattening pigs

The aim of this study was to investigate the effect of a strategic deworming program on Ascaris suum infection levels and technical performance parameters in fattening pigs. Eighteen fattening stables were selected and divided into two groups. Group 1 consisted of 9 stables in which the fattening pigs tested seropositive for Ascaris, indicative for the presence of Ascaris eggs in the stable, whereas group 2 consisted of 9 stables in which the fattening pigs tested seronegative for Ascaris, indicating of a low or absent environmental contamination with Ascaris eggs. The production in each stable was monitored for a period of 7 consecutive fattening rounds. The first of these 7 fattening rounds (i.e. round 0), during which no intervention took place in the deworming strategy applied in the stable, served as a historical control. A deworming program using 200 mg/ml fenbendazole oral suspension in drinking water for 2 days every 6 weeks was implemented for a period of 6 consecutive fattening rounds. For each fattening round and for each stable, technical performance parameters including average daily growth, feed conversion ratio, days in fattening and the percentage of affected livers were obtained from the producers. Blood was collected from 10 randomly selected animals per stable at the end of each fattening round and evaluated for the presence of anti-Ascaris antibodies using 2 different serological tests, namely the AsHb- and the L3-Lung ELISA. The serological results obtained indicated a lower exposure of the animals to Ascaris after the implementation of a strategic deworming program. A significant decline in anti-Ascaris antibody levels was detectable in the stables that originally tested positive for Ascaris and was already visible after one treatment round. The outcomes of hierarchical linear mixed models indicated that the level of L3-Lung antibody reactivity was a significant predictor of decreased ADG, increased FCR and prolonged DIF for the Ascaris-positive herds, indicating an effect of Ascaris infections on productivity.

Serological examination of fattening pigs reveals associations between Ascaris suum, lung pathogens and technical performance parameters

Diagnosing the presence of the highly prevalent and economically important pig parasite Ascaris suum on fattening farms has so far been challenging. Currently, only the number of livers affected at slaughter is routinely used to measure parasite exposure. However, recently, a new serological test was developed based on the detection of antibodies to the A. suum haemoglobin molecule. The test showed to be highly sensitive for the detection of exposure to A. suum in fattening pigs. In this study we first compared the performance of A. suum serology versus the percentage of affected livers at slaughter, subsequently we investigated potential associations between A. suum infection levels and exposure to important lung pathogens and finally we identified correlations between serological data and technical performance parameters (TPIs) from 20 Belgian and 20 German pig fattening farms. In both Belgian and German farms, a significant relationship was detected between elevated average Ascaris serology and percentages of affected livers (ρ=0.63 and ρ=0.75, respectively). On the Belgian farms, both Ascaris serology and the percentage of affected livers were negatively correlated with average daily gain (ADG) (ρ=-0.69 and ρ=-0.56, respectively). Using the German dataset, only a borderline negative association was detected between the percentage of affected livers and the ADG (ρ=-0.44, P=0.053). In contrast, only in the German farms, correlations between the percentage of affected lungs at slaughter and elevated presence of A. suum and several other airway pathogens were detected. To conclude, this study indicates that serological screening for A. suum on fattening farms is an attractive new diagnostic tool that can be used to indicate the presence of roundworm infection by measuring infection intensity. Furthermore the results of this study also add weight to the evidence that both roundworm infections as well as herd exposure to airway pathogens have a significant impact on farm productivity and hence, that all these factors should to be taken into account when assessing pig health and farm productivity.

Helminths and their implication in sepsis - a new branch of their immunomodulatory behaviour?

The prevalence of autoimmune and allergic disorders has dramatically increased in developed countries, and it is believed that our ‘cleaner living’ reduces exposure to certain microorganisms and leads to deviated and/or reduced regulation of the immune system. In substantiation of this health hygiene hypothesis, multiple epidemiological studies and animal models have characterized the protective immune responses induced by helminths during auto-inflammatory disorders. The beneficial effects of such helminths, like schistosomes and filariae, are thought to lie in their immunomodulatory capacity, which can be induced by different life-cycle stages or components thereof. In addition to suppressing autoimmunity recent evidence indicates that concurrent helminth infections also counterbalance exacerbated pro-inflammatory immune responses that occur during sepsis, improving survival. As with allergy, epidemiological studies have observed a steady rise in severe sepsis cases and although this may have resulted from several factors (immunosuppressive drugs, chemotherapy, transplantation, increased awareness and increased surgical procedures), it is tempting to hypothesize that the lack of helminth infections in Western countries may have contributed to this phenomenon. This review summarizes how helminths modulate host immunity during sepsis, such as manipulating macrophage activation and provides an overview about the possible implications that may arise during overwhelming bacterial co-infections.

This well written review gives a comprehensive overview on the immunopathology of sepsis and the modulation of immune responses by helminths. It provides evidence that helminths or components thereof may improve the outcome of severe infections. This will allow the development of therapeutic strategies to fight infections and sepsis.

Polymicrobial respiratory disease in pigs

Respiratory disease in pigs is common in modern pork production worldwide and is often referred to as porcine respiratory disease complex (PRDC). PRDC is polymicrobial in nature, and results from infection with various combinations of primary and secondary respiratory pathogens. As a true multifactorial disease, environmental conditions, population size, management strategies and pig-specific factors such as age and genetics also play critical roles in the outcome of PRDC. While non-infectious factors are important in the initiation and outcome of cases of PRDC, the focus of this review is on infectious factors only. There are a variety of viral and bacterial pathogens commonly associated with PRDC including porcine reproductive and respiratory syndrome virus (PRRSV), swine influenza virus (SIV), porcine circovirus type 2 (PCV2), Mycoplasma hyopneumoniae (MHYO) and Pasteurella multocida (PMULT). The pathogenesis of viral respiratory disease is typically associated with destruction of the mucocilliary apparatus and with interference and decrease of the function of pulmonary alveolar and intravascular macrophages. Bacterial pathogens often contribute to PRDC by activation of inflammation via enhanced cytokine responses. With recent advancements in pathogen detection methods, the importance of polymicrobial disease has become more evident, and identification of interactions of pathogens and their mechanisms of disease potentiation has become a topic of great interest. For example, combined infection of pigs with typically low pathogenic organisms like PCV2 and MHYO results in severe respiratory disease. Although the body of knowledge has advanced substantially in the last 15 years, much more needs to be learned about the pathogenesis and best practices for control of swine respiratory disease outbreaks caused by concurrent infection of two or more pathogens. This review discusses the latest findings on polymicrobial respiratory disease in pigs.

Bacteria isolated from 25 hydatid cysts in sheep, cattle and goats

Bacteria were isolated from 12 of 25 hydatid cysts collected from the lungs and livers of cattle, sheep and goats slaughtered in the province of Messina, Sicily, Italy. Citrobacter freundii was isolated from seven of the cysts, Aeromonas hydrophila from three, Staphylococcus species from two, Salmonella species from two and Escherichia coli and Proteus vulgaris from one.

Coinfection of pigs with porcine respiratory coronavirus and Bordetella bronchiseptica

Coinfection with two or more pathogens is a common occurrence in respiratory diseases of most species. The manner in which multiple pathogens interact is not always straightforward, however. Bordetella bronchiseptica and porcine respiratory coronavirus (PRCV) are respiratory pathogens of pigs whose relatives, B. pertussis and the SARS virus, cause respiratory disease in humans. In an initial experiment, the effect of coinfection of PRCV and B. bronchiseptica was examined in thirty, 4-week-old pigs (10 pigs/group) that were infected with either PRCV or B. bronchiseptica, or both PRCV and B. bronchiseptica. An additional 10 pigs served as sham infected controls. Five pigs from each group were euthanized at 4 and 10 days post-infection. Gross and histopathological lung lesions were more severe in the coinfected group as compared to the groups infected with B. bronchiseptica or PRCV alone. In order to investigate the potential role of proinflammatory cytokines in disease severity after coinfection, a second experiment was performed to examine cytokine transcription in alveolar macrophages from single and dually infected pigs. A total of 48 pigs were divided equally into groups as above, but 4 pigs from each group were euthanized at 1, 4 and 10 days post-infection. Coinfected pigs showed a greater and more sustained transcription of proinflammatory cytokines, especially IL-6 and MCP-1, than pigs infected with either PRCV or B. bronchiseptica alone. Thus, there appears to be a synergistic effect between PRCV and B. bronchiseptica with regards to proinflammatory cytokine transcription that may partially explain the increased severity of pneumonia in coinfected pigs.

The migration of Ascaris suum larvae, and the associated pulmonary inflammatory response in susceptible C57BL/6j and resistant CBA/Ca mice

Ascariasis is an important infection in humans (Ascaris lumbricoides) and pigs (Ascaris suum) and individuals appear to be predisposed to either heavy or light worm burdens. These extremes of susceptibility and resistance are represented in a mouse model by 2 strains of mice, CBA mice showing high resistance to infection and C57BL/6 which are highly susceptible, as reflected in worm burdens in the lungs 6-7 days after infection. In an attempt to identify the point at which the difference between these 2 strains is first manifested, we quantified worm burdens at key stages during infection leading up to the pulmonary stage of development. Thus mice were inoculated with fully embryonated A. suum eggs and larval burdens were enumerated in the large intestine and rectum, liver and lungs of the 2 strains at 6 h post-inoculation (p.i.) and on each of days 1-8 p.i. inclusively. A higher percentage of the total inoculum was recovered from the intestine/rectum of C57BL/6j mice in contrast to CBA/Ca mice at 6 h p.i. Larvae were recovered from the intestinal contents and also whilst actively migrating through the large intestinal wall. The number of larvae recovered was significantly reduced in CBA/Ca mice in contrast to C57BL/6j mice between the phase of migration from the liver and arrival in the lungs. The combined results of the inoculation of mice with corticosteroids and the examination of the change in profile and number of leukocytes present in bronchoalveolar lavage fluid suggested that the pulmonary inflammatory immune response was not prominently involved in primary protection of mice to A. suum infection in the latter days of infection in the lungs. The susceptible C57BL/6j mice produced a BAL response almost twice as intense as that of resistant CBA/Ca mice with stronger neutrophil, lymphocyte and eosinophil but not macrophage components, suggesting that the difference in worm burdens between the strains was generated earlier in the course of infection. These results were further corroborated by a histological examination of the lung tissues which showed that the passage of the larval stages of A. suum through the mouse lungs was associated with a marked inflammatory response in both strains. Again, C57BL/6j mice exhibited increased inflammation relative to CBA/Ca mice. Hence some hepatic/post-hepatic factor that varies between the 2 strains, but exerts its effect before the lung phase plays a critical role in determining the success of larvae through the host tissues. The possible sites of this host defence are reviewed.

Studies on the interaction between Salmonella enterica ser. Typhimurium and intestinal helminths in pigs

Concomitant infections with helminths and bacteria may affect the course and the resulting disease outcome of the individual infections. Salmonella, Oesophagostomum, Trichuris and Ascaris coexist naturally in pig herds in Denmark, and possible interactions were studied. Pigs in one experiment were trickle infected with low or moderate dose levels of Oesophagostomum spp. and challenge infected with S. Typhimurium. In another experiment, pigs were inoculated with S. Typhimurium followed by a challenge exposure to either Oesophagostomum, Trichuris or Ascaris. Enhancement of the Salmonella infection was not demonstrated in either experiment. The helminth effect on the pigs was modest and may explain the lack of influence on the Salmonella infection. A previous experiment with a larger Oesophagostomum infection level resulted in enhancement of the S. Typhimurium infection. A dose dependency of the interaction is therefore suggested. However, the relatively high worm burdens in the present study suggest that infection with these common pig helminths does generally not influence the course of concurrent S. Typhimurium infections under natural conditions.