Home › Livestock Farming › Article

How is swine mycoplasmal pneumonia diagnosed? Introduction to common diagnostic methods

Livestock Farming 0 views
How to treat pig diseases: What are the methods for diagnosing swine mycoplasmal pneumonia?
Swine mycoplasmal pneumonia is a cell-wall-free prokaryote, the simplest self-replicating organism between bacteria and viruses. Swine mycoplasmal pneumonia is an extracellular pathogen that binds tightly to the ciliated epithelial cells of the pig's lower respiratory tract, rather than invading the body through tissue. During infection in the body, swine mycoplasmal pneumonia recognizes specific receptors on the ciliated cells of the respiratory mucosa and multiplies in the respiratory tract. It is generally believed that the specific adhesion of swine mycoplasmal pneumonia to the cilia of the respiratory mucosa is a prerequisite for causing mycoplasmal pneumonia. In the course of feeding and management, when a pig is infected with swine mycoplasmal pneumonia alone, the pig's body weight and feed conversion rate will not decrease, nor will it affect the increase of fat and protein in the pig's body. In the short term, it will not affect the pig's growth. However, when swine mycoplasmal pneumonia co-infects with other pathogens, the pig's clinical symptoms worsen.

The methods for diagnosing swine mycoplasmal pneumonia are as follows:

1. Clinical diagnosis of swine mycoplasmal pneumonia

The main clinical symptoms of swine mycoplasmal pneumonia are chronic dry cough, stunted growth, delayed development, high morbidity, low mortality and slow spread after infection, with a tendency to recur. However, Mycoplasma hyopneumoniae easily co-infects with other pathogens such as Actinobacillus pleuropneumoniae, porcine reproductive and respiratory syndrome virus, and Pasteurella multocida, complicating the clinical symptoms of swine mycoplasmal pneumonia, and some infected pigs do not show clinical symptoms at all; therefore, swine mycoplasmal pneumonia can only be suspected through clinical symptoms.

2. Pathological diagnosis of swine mycoplasmal pneumonia

During pathological necropsy, the lesions are found mainly in the lungs, hilar lymph nodes and mediastinal lymph nodes, with no special lesions in other tissues and organs. The characteristic lesions are enlarged lungs with varying degrees of emphysema and edema, and symmetric confluent bronchopneumonia lesions appearing in the cardiac lobe, apical lobe, intermediate lobe of both lungs and, in some cases, the anterior lower margin of the diaphragmatic lobe, with the cardiac lobe being the most obvious, followed by the apical lobe and intermediate lobe.
 
3. Pathogen detectiontechniquesfor diagnosing swine mycoplasmal pneumonia

1) Pathogen isolation and culture

Isolating Mycoplasma hyopneumoniae from the affected site is a specific method for confirming that a pig has MPS. However, swine mycoplasmal pneumonia is one of the most difficult pathogens to isolate and identify; it grows slowly and is often masked by overgrowth of Mycoplasma hyorhinis, and after drugtreatmentor in recovered pigs, it is also very difficult to isolate swine mycoplasmal pneumonia again. Although the isolation rate of swine mycoplasmal pneumonia from lesion sites has gradually increased through improved isolation media and isolation methods, in most cases isolation and culture diagnosis is still not feasible.

2) Immunoenzymetechniques

Enzyme-linked immunoperoxidase and indirect immunoperoxidase tests are used to detect Mycoplasma hyopneumoniae in diseased lungs, overcoming the shortcomings of fluorescent antibodytechniques, which cannot effectively detect chronically infected pigs, require fresh frozen tissue and a fluorescence microscope, and cannot preserve samples long-term. When ELIP is used to examine frozen lung sections and bronchial smears, the mycoplasma is stained as pale reddish-brown pleomorphic granules, and the reaction is very stable. Doster et al. fixed and paraffin-embedded pig lungs with formalin and used the indirect peroxidase test to detect Mhp; clearly structured Mhp could be observed with an optical microscope, and samples could be preserved long-term for re-evaluation, making it more sensitive than the fluorescent antibody method. This method can be used when fresh tissue or other specific tests are unavailable.

Summary:

There are many diagnostic methods for swine mycoplasmal pneumonia. The above are several detectiontechniquesthat are widely reported and commonly used at home and abroad, and each method has its own advantages and disadvantages. In clinical application, in addition to selecting a suitable detectiontechniqueaccording to the test conditions and purpose, a comprehensive diagnosis should also be made in combination with clinical symptoms and histopathological lesions, so as to obtain correct and reliable diagnostic results.

 

Related Articles