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Mycoplasma hyopneumoniae infection in pigs: duration of the disease and resistance to reinfection
Abstract
Forty-eight hysterectomy produced piglets reared in a pathogen-free environment were housed in 4 separate units. Three groups were intratracheally challenged with M hyopneumoniae at 2 wk, or at 16 wk, or at 2 and 16 wk of age. The fourth group was uninfected and received broth medium. Coughing started 2 weeks after the first infection but the booster infection did not induce any coughing. Macroscopic lesions, typical of mycoplasmal pneumonia, were noted 1 wk post-infection. After 7-9 wk, piglets showed recovering lesions. In the group that was twice infected, only 1 pig had extensive pneumonia after the second infection. The remaining pigs only had recovering lesions (RL) (resulting from the first challenge). Histopathology and scanning electron microscopy confirmed the macroscopic observations. Antibodies were detected by ELISA and immunoblotting at 3-4 wk post-infection, peaking after 11-12 wk and then gradually decreasing. However, the antibody response increased after the second infection. These findings showed a noticeable recovery following infection with M hyopneumoniae and a clear resistance to pneumonia following the booster infection.
... In the present paper, the term cranioventral pulmonary consolidation (CVPC) will be used to describe Mycoplasma hyopneumoniae (M. hyopneumoniae)-like gross lung lesions, which consist of purple to grey areas of pulmonary consolidation, mainly located bilaterally in the apical intermediate and accessory lobes, including the cranial parts of the diaphragmatic lobes in the most extensive cases [12,13]. In the literature, also other terms have been used to describe these lesions such as catarrhal pneumonia, bronchopneumonia, Mycoplasma-pneumonia, Mycoplasma-like lesions or enzootic pneumonia-like lesions. ...
... In incipient cases in which the consolidation does not completely affect the entire parenchyma, the lung may still float in water due to the presence of air. It takes approximately 7 to 10 weeks for the lesions to be healed, with no evidence of gross lesions anymore [12]. However, in chronic stages (more frequently seen at the slaughterhouse), consolidated areas may look purple to grey, and usually evolve to scarring and tissue retraction. ...
... However, in chronic stages (more frequently seen at the slaughterhouse), consolidated areas may look purple to grey, and usually evolve to scarring and tissue retraction. These interlobular scar retractions of connective tissue are also called fissures [12,17]. These chronic lesions are, usually, not as well coloured and demarcated as acute ones, and their scoring could be more challenging. ...
Porcine respiratory disease is one of the most important health problems in pig production worldwide. Cranioventral pulmonary consolidation (CVPC) and pleurisy are the two most common lesions in the respiratory tract of slaughtered pigs. The present review paper discusses pathogens involved in the lesions, lesion prevalence, scoring systems, advantages and disadvantages of slaughterhouse examination, and the impact of CVPC and pleurisy on performance, carcass, and meat quality. Cranioventral pulmonary consolidation and pleurisy in slaughter pigs are characteristic for infections with Mycoplasma hyopneumoniae and Actinobacillus pleuropneumoniae , respectively, although other pathogens may cause similar lesions and/or be involved in their development. The overall prevalence of CVPC and pleurisy in slaughter pigs are still high, being the prevalence of CVPC generally higher than that of chronic pleurisy. The advantages and disadvantages of slaughterhouse examination are discussed in relation to practical aspects, the assessment of lesions, the number and representativeness of the examined animals and the interpretation and value of the results for the stakeholders. The main scoring methods for CVPC and pleurisy are shortly reviewed. In general, scoring methods can be applied rapidly and easily, although significant variation due to abattoir and observer remains. Artificial intelligence-based technologies that automatically score lesions and facilitate processing of data may aid solving these problems. Cranioventral pulmonary consolidation and pleurisy have a major negative impact on pig performance, and the effects increase the extension of the lesions and/or presence of multiple lesions. The performance losses caused by these lesions, however, vary significantly between studies and farms, possibly due to differences in study population and used methodology. Both lesions also have a negative impact on different carcass and meat quality parameters, leading to increased risk for poor processing and storage of the carcasses. Monitoring lung lesions of slaughter pigs should be optimized and implemented routinely; however, it is recommended to complement this information with farm data and laboratory results for specific pathogens.
... Lung lesion dynamics Lung lesions associated with mycoplasmal pneumonia are naturally chronic. Pneumonia may start developing one week after infection (Underdahl et al., 1980;Kobisch et al., 1993;Lorenzo et al., 2006) and increase progressively until reaching maximal extension and severity four weeks post-infection ( Fig. 1; Garcia-Morante et al., 2017b). After peaking, macroscopic lung lesions may persist until week eight post-infection and decrease gradually thereafter (Kobisch et al., 1993;Sørensen et al., 1997). ...
... Pneumonia may start developing one week after infection (Underdahl et al., 1980;Kobisch et al., 1993;Lorenzo et al., 2006) and increase progressively until reaching maximal extension and severity four weeks post-infection ( Fig. 1; Garcia-Morante et al., 2017b). After peaking, macroscopic lung lesions may persist until week eight post-infection and decrease gradually thereafter (Kobisch et al., 1993;Sørensen et al., 1997). If there are no further complications, mycoplasmal pneumonia is generally resolved 12 weeks post-infection, when the remaining gross lesions may consist of interlobular scarring with tissue retraction (Kobisch et al., 1993;Sørensen et al., 1997). ...
... After peaking, macroscopic lung lesions may persist until week eight post-infection and decrease gradually thereafter (Kobisch et al., 1993;Sørensen et al., 1997). If there are no further complications, mycoplasmal pneumonia is generally resolved 12 weeks post-infection, when the remaining gross lesions may consist of interlobular scarring with tissue retraction (Kobisch et al., 1993;Sørensen et al., 1997). However, studies that have followed pigs for long periods after M. hyopneumoniae experimental inoculation have reported CVPC in about 40% of the inoculated pigs by 13 weeks post-inoculation ) and some degree of pneumonia up to 26 weeks post-infection (Fano et al., 2005). ...
Mycoplasma hyopneumoniae remains one of the most problematic bacterial pathogens for pig production. Despite an abundance of observational and laboratory testing capabilities for this organism, diagnostic interpretation of test results can be challenging and ambiguous. This is partly explained by the chronic nature of M. hyopneumoniae infection and its tropism for lower respiratory tract epithelium, which affects diagnostic sensitivities associated with sampling location and stage of infection. A thorough knowledge of the available tools for routine M. hyopneumoniae diagnostic testing, together with a detailed understanding of infection dynamics, are essential for optimizing sampling strategies and providing confidence in the diagnostic process. This study reviewed known information on sampling and diagnostic tools for M. hyopneumoniae and summarized literature reports of the dynamics of key infection outcomes, including clinical signs, lung lesions, pathogen detection, and humoral immune responses. Such knowledge could facilitate better understanding of the performance of different diagnostic approaches at various stages of infection.
... After experimental infection, M. hyopneumoniae-specific serum IgG antibodies are detected 3-4 weeks post-infection (pi), peak after 11-12 weeks and then decrease very gradually [44]. After booster infection, serum antibody titers clearly increase and then slowly decline again [44]. ...
... After experimental infection, M. hyopneumoniae-specific serum IgG antibodies are detected 3-4 weeks post-infection (pi), peak after 11-12 weeks and then decrease very gradually [44]. After booster infection, serum antibody titers clearly increase and then slowly decline again [44]. Interestingly, pigs infected with a highly virulent strain appear to seroconvert earlier than pigs infected with a low virulent strain [45]. ...
Mycoplasma hyopneumoniae ( M. hyopneumoniae ) is one of the primary agents involved in the porcine respiratory disease complex, economically one of the most important diseases in pigs worldwide. The pathogen adheres to the ciliated epithelium of the trachea, bronchi, and bronchioles, causes damage to the mucosal clearance system, modulates the immune system and renders the animal more susceptible to other respiratory infections. The pathogenesis is very complex and not yet fully understood. Cell-mediated and likely also mucosal humoral responses are considered important for protection, although infected animals are not able to rapidly clear the pathogen from the respiratory tract. Vaccination is frequently practiced worldwide to control M. hyopneumoniae infections and the associated performance losses, animal welfare issues, and treatment costs. Commercial vaccines are mostly bacterins that are administered intramuscularly. However, the commercial vaccines provide only partial protection, they do not prevent infection and have a limited effect on transmission. Therefore, there is a need for novel vaccines that confer a better protection. The present paper gives a short overview of the pathogenesis and immune responses following M. hyopneumoniae infection, outlines the major limitations of the commercial vaccines and reviews the different experimental M. hyopneumoniae vaccines that have been developed and tested in mice and pigs. Most experimental subunit, DNA and vector vaccines are based on the P97 adhesin or other factors that are important for pathogen survival and pathogenesis. Other studies focused on bacterins combined with novel adjuvants. Very few efforts have been directed towards the development of attenuated vaccines, although such vaccines may have great potential. As cell-mediated and likely also humoral mucosal responses are important for protection, new vaccines should aim to target these arms of the immune response. The selection of proper antigens, administration route and type of adjuvant and carrier molecule is essential for success. Also practical aspects, such as cost of the vaccine, ease of production, transport and administration, and possible combination with vaccines against other porcine pathogens, are important. Possible avenues for further research to develop better vaccines and to achieve a more sustainable control of M. hyopneumoniae infections are discussed.
... Typical EP gross lung lesions are characterized by well defined, greyish to reddish depressed cranioventral areas of consolidation. Microscopically, these areas correspond with a pattern of bronchointerstitial pneumonia with lymphoid cells infiltrating the lamina propria of bronchioles to a differing extent and, finally, evolving a hyperplasia of bronchusassociated lymphoid tissue (BALT) at peribronchial, peribronchiolar and perivascular levels [6][7][8]. ...
... However, the prevalence of microscopic lung lesions has been reported to be much higher than the prevalence of macroscopic ones when investigating non-infectious factors associated with gross and microscopic lung lesions in slaughtered pigs [9]. In this sense, whereas gross lesions, such as MLL or pleurisy, can take between 8 and 12 weeks to heal and disappear [6,7,27], microscopic lesions may persist for longer [9]. Thus, histopathology can bring to light the presence of lesions that grossly can go unnoticed. ...
Background
Mycoplasma hyopneumoniae causes a chronic respiratory disease that produces important economic losses due to poor productive performance, increased mortality and costs for several control strategies. The prevalence of mycoplasma-like lesions (MLL) at abattoir has been widely studied in different countries, making use of different scoring systems. However, most of them are difficult to apply in abattoirs with high number of pigs sacrificed per hour. For that reason, it is necessary to adapt the scoring system to the reality of the modern abattoir, even if there is a loss of accuracy. Our purpose was to investigate the prevalence and severity of MLL at abattoirs in Spain and Portugal using a 0 to 5 scoring system adapted to abattoirs with high number of sacrificed pigs per hour and to highlight the histopathological diagnosis as confirmatory method to identify patterns of pneumonia correlated to gross lesions.
Results
Cranioventral pulmonary consolidation, a typical MLL, was the most frequent lung lesion (30.97 %) detected at the abattoir, followed by dorsocaudal infarcts with pleurisy (12.51 %) and pleurisy alone (6.26 %). The average score for all examined lungs at abattoir was 1.99 out of 5 points. The histopathological study revealed that the 78.17 % of the randomly selected lungs with MLL presented microscopic lesions compatible with M. hyopneumoniae infection. Most bronchointerstitial and interstitial pneumonia lesions had a chronic course while most suppurative and fibrinous bronchopneumonia lesions had an acute course and a higher degree of severity. The combination of microscopic lesions more frequently observed was bronchointerstitial pneumonia + interstitial pneumonia + suppurative bronchopneumonia.
Conclusions
The prevalence of MLL at abattoir was 30.97 %, however, after microscopic examination the real prevalence of lungs with lesions compatible with M. hyopneumoniae infection was reduced up to 24.21 %. The six more prevalent combinations of lesions in the microscopic study involved the 66.13 % of examined lungs, and in all of them, microscopic lesions characteristic of M. hyopneumoniae infection were found, what supports the importance of M. hyopneumoniae as a primary pathogen in cases of PRDC.
... Typical EP gross lung lesions are characterized by well de ned, greyish to reddish depressed cranioventral areas of consolidation. Microscopically, these areas correspond with a pattern of bronchointerstitial pneumonia with lymphoid cells in ltrating the lamina propria of bronchioles to a differing extent and, nally, evolving a hyperplasia of bronchus-associated lymphoid tissue (BALT) at peribronchial, peribronchiolar and perivascular levels [6,7,8]. ...
... However, the prevalence of microscopic lung lesions has been reported to be much higher than the prevalence of macroscopic ones when investigating non-infectious factors associated with gross and microscopic lung lesions in slaughtered pigs [9]. In this sense, whereas gross lesions, such as MLL or pleurisy, can take between 8 to 12 weeks to heal and disappear [6,7,27], microscopic lesions may persist for longer [9]. Thus, histopathology can bring to light the presence of lesions that grossly can go unnoticed. ...
Background: Mycoplasma hyopneumoniae causes a chronic respiratory disease that produces important economic losses due to poor productive performance, increased mortality and costs for several control strategies. The prevalence of mycoplasma-like lesions (MLL) at abattoir has been widely studied in different countries, making use of different scoring systems. However, most of them are difficult to apply in abattoirs with high number of pigs sacrificed per hour. For that reason, it is necessary to adapt the scoring system to the reality of the modern abattoir, even if there is a loss of accuracy. Our purpose was to investigate the prevalence and severity of MLL at abattoirs in Spain and Portugal using a 0 to 5 scoring system adapted to abattoirs with high number of sacrificed pigs per hour and to highlight the histopathological diagnosis as confirmatory method to identify patterns of pneumonia correlated to gross lesions.
Results: Cranioventral pulmonary consolidation, a typical MLL, was the most frequent lung lesion (30.97 %) detected at the abattoir, followed by dorsocaudal infarcts with pleurisy (12.51 %) and pleurisy alone (6.26 %). The average score for all examined lungs at abattoir was 1.99 out of 5 points. The histopathological study revealed that the 78.17 % of the randomly selected lungs with MLL presented microscopic lesions compatible with M. hyopneumoniae infection. Most bronchointerstitial and interstitial pneumonia lesions had a chronic course while most suppurative and fibrinous bronchopneumonia lesions had an acute course and a higher degree of severity. The combination of microscopic lesions more frequently observed was bronchointerstitial pneumonia + interstitial pneumonia + suppurative bronchopneumonia.
Conclusions: The prevalence of MLL at abattoir was 30.97 %, however, after microscopic examination the real prevalence of lungs with lesions compatible with M. hyopneumoniae infection was reduced up to 24.21 %. The six more prevalent combinations of lesions in the microscopic study involved the 66.13 % of examined lungs, and in all of them, microscopic lesions characteristic of M. hyopneumoniae infection were found, what supports the importance of M. hyopneumoniae as a primary pathogen in cases of PRDC.
... Some studies reported that M. hyopneumoniae could infect pigs of various ages resulting in typical lesions of EP (43). In this study, the 28-day-old pigs infected with M. hyopneumoniae ES-2 strain for 38 days showed typical pneumonia in the accessory lobes, apical lobes, cardiac lobes, and the cranial portion of the caudal lobes of the lungs (Figure 4F). ...
Mycoplasma hyopneumoniae is the primary pathogen of swine enzootic pneumonia and causes great economic losses to the swine industry worldwide. In China, M. hyopneumoniae seriously hinders the healthy development of the native black pigs. To prevent and treat porcine respiratory disease caused by M. hyopneumoniae, the characteristics of M. hyopneumoniae strain ES-2 isolated from Chinese native black pig lungs with gross lesions at post-mortem were studied for the first time in this study. Strain ES-2 cell was round or oval cells and most sensitive to kanamycin. The diameters of most strain ES-2 cells ranged from 0.4 to 1.0 μm with maximum viability of 10¹⁰ CCU/ml. Experimental challenge of animals with strain ES-2 showed respiratory disease could be reproduced, with pneumonic lung lesions evident. Comparative genomics analysis identified that 2 genes are specific to pathogenic M. hyopneumoniae strains, which may be predicted to be a molecular marker. These findings suggest that the study on the characteristics of M. hyopneumoniae strain ES-2 will guide the rapid and accurate drug use in the clinic, and develop a theoretical foundation for accurately diagnosing and treating the infection caused by pathogenic M. hyopneumoniae.
... Microscopically, these areas are correlated to a pattern of bronchointerstitial pneumonia with lymphoid cells in ltrating the lamina propria of bronchioles to a differing extent and, nally, evolving an hyperplasia of the bronchus-associated lymphoid tissue (BALT) at peribronchial, peribronchiolar and perivascular levels [6,7]. ...
Background: Mycoplasma hyopneumoniae causes a chronic respiratory disease that produces important economic losses due to poor productive performance, increased mortality and increased costs due to treatment and control. The prevalence of mycoplasma-like lesions (MLL) at abattoir has been widely studied in different countries and different scoring systems have been used. However, most of them are difficult to apply in case of abattoirs with high number of pigs sacrificed per hour. For that reason, it is necessary to adapt the scoring system to the reality of the modern abattoir even if there is a loss of accuracy. Our purpose was to validate a mycoplasma-like scoring system at abattoirs with a high number of pigs per hour in Spain and Portugal using the histopathological diagnosis as confirmatory method to identify pattern of pneumonia correlated to gross lesion.
Results: Cranioventral pulmonary consolidation (MLL) was the most frequent lung lesion (30.97 %) detected at the abattoir, followed by dorsocaudal infarcts with pleurisy (12.51 %) and pleurisy alone (6.26 %). The average score calculated for all lungs examined at abattoir was 1.99 out of 5 points. The histopathological study revealed that the 78.17 % of the lungs with MLL randomly selected presented microscopic lesions compatible with M. hyopneumoniae infection. Most bronchointerstitial and interstitial pneumonia lesions had a chronic course while most suppurative and fibrinous bronchopneumonia lesions had an acute course and a higher degree of severity. The combination of microscopic lesions more frequently observed was bronchointerstitial pneumonia + interstitial pneumonia + suppurative bronchopneumonia. The average loss of ADWG calculated for all pigs included in the study according the extension of the lung lesions was 22.33 g/day.
Conclusions: The prevalence of MLL at abattoir was 30.97% but the microscopic examination of a sample of randomly selected lungs indicated that the real prevalence of lungs with lesions compatible with M. hyopneumoniae infection would be reduced to 24.21 %. The average score of MLL using a 0 to 5 points was 1.99 and the average loss of ADWG associated to those lesions was 22.33 g/day. The result of our study supports the importance of M. hyopneumoniae as primary pathogen in cases of PRDC.
Mycoplasma hyopneumoniae (M. hyopneumoniae) is considered the primary causative agent of porcine enzootic pneumonia (EP), a chronic contagious respiratory disease that causes economic losses. Obtaining new pathogenic isolates and studying the genome and virulence factors are necessary. This study performed a complete sequencing analysis of two Brazilian strains, UFV01 and UFV02, aiming to characterize the isolates in terms of the virulence factors and sequence type. The complete genome analysis revealed the main virulence genes (mhp385, mhp271, MHP_RS03455, p102, p97, p216, MHP_RS00555, mhp107) and ST-123, the presence of three toxin-related genes (tlyC, PLDc_2 and hcnC), and some genetic groups specific to these two isolates. Subsequently, the pathogenicity of the isolates was evaluated via an experimental infection conducted in a swine model. The study was divided into three groups, namely a negative control group (n = 4) and two test groups (n = 8), totaling 20 animals. They were challenged at 35 days of age with 10 7 CCU (Color Changing Units) M. hyopneumoniae via the intratracheal route. The UFV01 group showed earlier and higher seroconversion (IgG) (100%), while only 50% of the UFV02 group seroconverted. The same trend was observed when analyzing the presence of IgA in the bronchoalveolar lavage fluid (BALF) at 35 days post-infection (dpi). The UFV01 group had a mean macroscopic lesion score of 11.75% at 35 dpi, while UFV02 had 3.125%. Microscopic lesions were more severe in the UFV01 group. Based on laryngeal swab samples evaluated by qPCR, and the detection began at 14 days. The UFV01 group showed 75% positivity at 14 dpi. The UFV02 group also started excreting at 14 dpi, with a positivity rate of 37.5%. The results indicate that the UFV01 isolate exhibits higher virulence than UFV02. These findings may aid in developing new vaccines and diagnostic kits and establishing experimental models for testing.
This datasheet on Mycoplasma hyopneumoniae infections covers Identity, Overview, Associated Diseases, Pests or Pathogens, Distribution, Hosts/Species Affected, Diagnosis, Pathology, Epidemiology, Impacts, Prevention/Control, Further Information.
Abstract Background An outdoor pig herd was affected by severe respiratory disease in one out of three pastures. At necropsy, Mycoplasma hyopneumoniae and Pasteurella multocida were detected in the lungs, as well as the lung worm Metastrongylus apri. The life cycle of Metastrongylus spp. includes earthworms as intermediate hosts, and since domestic pigs mainly are reared indoors, lungworm infections have not been diagnosed in domestic pigs in Sweden for decades, not even in pigs reared outdoors. Therefore, this disease outbreak was scrutinised from the view of validating the impact of Metastrongylus spp. Results At the time of the disease outbreak, neither eggs of Metastrongylus spp., Trichuris suis nor Ascaris suum were detected in faeces of pigs aged ten weeks. In contrast, five-months-old pigs at the pasture with respiratory disease shed up to 3800 eggs per gram (Epg) of Ascaris suum and up to 1100 Epg of Trichuris suis, whereas eggs of these parasites were not demonstrated in healthy pigs aged six months at another pasture. Low numbers of eggs from Metastrongylus spp. (
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