References
Mycoplasma hyopneumoniae as a causative agent of porcine enzootic pneumonia
Abstract
Mycoplasma hyopneumoniae is a very important pathogen which causes enzootic pneumonia (EP) affecting pig herds worldwide. M. hyopneumoniae establishes itself in the respiratory system causing pathological changes, and resultant pneumonic lesions can be detected at slaughter via lung examination, appearing as red to pink lesions which resolve over time, leaving scar tissue on the lobes. Mycoplasma spp. infection can be complicated by coinfections with other pathogens such as swine influenza virus (SIV) and porcine circovirus (PCV2). These coinfections result in worsening of clinical symptoms and lung lesions, therefore increasing the impact on performance of the affected animals. Therefore, it is important that focus is placed on improving overall respiratory health and managing overall herd health, rather than just solely focusing on M. hyopneumoniae. Management practices should be implemented to control the disease, which commonly involve vaccination to reduce the impacts of the disease. Effective vaccination is important, and can be ensured by correct vaccine handling, storage and administration. The vaccine used can also play a part in the success of the vaccination programme so this should also be assessed, which can be done via lung examination and noting of clinical signs and performance parameters. When vaccination is successful, the level of lung lesions should be reduced, performance improved and consistency between batches, demonstrating that respiratory health is more stable.
Mycoplasma hyopneumoniae is one of the most important primary pathogens of the porcine respiratory system and is the causative agent of enzootic pneumonia (EP) (Fraile et al, 2010). M. hyopneumoniae is also a major contributor to development of the porcine respiratory disease complex (PRDC) (Garcia-Morante et al, 2016). M. hyopneumoniae is widespread throughout the pig population and is endemic on most farms worldwide. Pneumonic lung lesions as a result of M. hyopneumoniae are commonly observed in the slaughterhouse, with average herd level prevalence reported as 24%, ranging up to 88% (Maes et al, 2001), demonstrating the large variability observed between units depending on individual farm situation. Co-infections are very important in respiratory disease, as interaction of multiple pathogens has been shown to increase the severity of clinical signs (Saade et al, 2020) and therefore the impact on performance. Enzootic pneumonia has a large economic impact on the pig industry, primarily because of the cost of treatment, reduced performance and increased mortality as a result of secondary infections (Holst et al, 2015). Therefore, implementation of control measures is extremely important to improve animal health and consequently productivity on farm. Management practices form an integral part of this control plan, including improved biosecurity and hygiene, which may be accompanied with vaccination. There are numerous vaccines available which vary in the vaccination schedule, but the ultimate goal should be reduction of lung lesions and performance losses as a result of M. hyopneumoniae.
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