Mycoplasma hyopneumoniae in swine: Review

Abstract

Mycoplasma hyopneumoniae is the primary pathogen of the pathology known as enzootic pneumonia, a highly contagious chronic respiratory disease that affects pigs, characterized by high morbidity and low mortality. The etiologic agent is found in the respiratory mucosa, adhered to the ciliated epithelium of the trachea, bronchi and bronchioles. Infections occur worldwide and have major economic impacts for the pig industry. The present work aimed to carry out a review of the control strategies and economic losses caused by M. hyopneumoniae, for this purpose research was carried out based on information acquired from scientific articles, books, theses and dissertations on M. hyopneumoniae. The transmission of the agent occurs mainly by direct contact of the respiratory secretions of a pig with a susceptible pig. The disease is most commonly seen in growing and finishing animals. After the infection, destruction of the mucociliary system occurs, together with the alteration of the immune response, increases the susceptibility of pigs affected to secondary infections. Clinical signs are based on dry cough, runny nose, low herd development, lack of shine and uneven score among piglets. The severity of the lesions depends on environmental factors, management and host immunity. There are several diagnostic tests that can detect the agent, the choice of the test depends on the patient's clinical circumstances and property, the most used being the Polymerase Chain Reaction (PCR) and ELISA tests. Vaccination is commonly used, studies have observed a reduction in bacterial loads and a drop in the severity of clinical signs in vaccinated pigs, currently available vaccines are economical and easy to access, but some studies have concluded that neither vaccination nor preventive medication can prevent infection and adhesion of M. hyopneumoniae to the hair cells of the respiratory tract to occur. research is needed to improve understanding of the microorganism's mechanisms of action and its interaction with the host and other pathogens, as this research can assist in the development and improvement of control methods, such as the development of new vaccines that provide better protection to the animal.