Information of Mycoplasma gallisepticum

Mycoplasma gallisepticum (MG) infection is often referred to as chicken chronic respiratory disease (CRD), which is characterized by respiratory rales, cough, runny nose, conjunctivitis. Clinical manifestations of slow development and a long course. "Balloon disease" is a severe form of bursitis due to MG infection or infection with certain respiratory viruses (such as infectious bronchitis or Newcastle disease) and infection of the mycoplasma synovialis, usually by E. coli infection.

Way for spreading

Susceptible flocks can be spread horizontally by direct or indirect contact, causing clinical or subclinical infection leading to high infection rates or disease prevalence in flocks. Upper respiratory tract and conjunctiva are aerosols and droplets in the path of the strain into the body. MG in the host survival in vitro rarely more than a few days, so the prevalence of MG carriers is the key. However, other contaminants such as dust, droplets, feathers and other routes of transmission in the air, combined with poor biosecurity and some human factors, could cause a wider outbreak of the disease. MG in chicken manure at 20℃ can survive 1-3d, 20℃ in cotton can survive 3d or 37℃ survival 1d, 37℃ in the egg yolk can survive 18 weeks or 20 ℃ survive for 6 weeks.

It is known that the vertical transmission of MG is mainly through the eggs produced by the naturally infected hens. In the acute phase of the disease, when the number of MG reaches the peak in the respiratory tract, the propagation speed is the fastest. Infected offspring chickens hatch out, can cause the level of the spread of MG, even if a small part of the spread of chicken infection is very low, but also may lead to the entire flock of all chickens are infected.

Epidemiology

Mycoplasma gallisepticum infection is prevalent in chicken farms around the world. According to the serological investigation, the infection rate averaged between 70% and 80%.

Affecting the prevalence of Mycoplasma gallisepticum infection factors, in addition to the pathogenicity of mycoplasma itself, the chicken is obviously a factor of age, the resistance of chickens to Mycoplasma infection with age and strengthen. Concurrent infection of Mycoplasma gallisepticum infection has a considerable impact, even pathogenicity is not strong Mycoplasma gallisepticum infection, often due to vaccination against Newcastle disease vaccine or infectious bronchitis vaccine outbreak of mycoplasma disease clinical diagnosis. This is because these viral infections can promote mycoplasma to a hundredfold, thousands of times or even higher rate of development, and finally lead to disease outbreaks. In addition to the above two can promote the virus infection of mycoplasma infection, there are infectious laryngotracheitis virus, avian adenovirus, influenza A virus and reovirus. In bacteria, Escherichia coli and Mycoplasma gallisepticum synergistic pathogenicity is extremely significant, single infection of Mycoplasma gallisepticum, chickens in the little or no death, if at the same time colorectal infection, the condition is very serious, causing heavy losses death. Pseudomonas aeruginosa and Haemophilus can also promote the severity of mycoplasma infection.

Environmental factors also play an important role in the prevalence of mycoplasma infection. Chicken crowds exacerbate the spread of pathogens, while crowding is a stress, reducing the resistance of chickens. Chicken fouling, fecal collection set, the air increased the content of ammonia to stimulate the respiratory mucosa to facilitate the development of mycoplasma. Ambient temperature also has a significant impact on infection, the higher the temperature, the higher the rate of chicken infection.

Mycoplasma spread mainly in two ways. One is the direct contact with the way, is infected with poultry exhaled with mycoplasma droplets transmitted through the respiratory tract to the same cage or chicken with the cage. Another way is through the egg, the pathogen infected chicken eggs transmitted to the next generation, this approach may be more important. In some areas, especially in developing countries, the use of common egg chicken embryos are often used to make live poultry vaccines, which are contaminated by egg-borne mycoplasma in chick embryos and transmitted to vaccinated chickens. Of the vaccine in the role of infection can not be ignored.

Nutritional deficiencies can also lead to the occurrence of mycoplasma disease, there was a lack of vitamin A, which led to the outbreak of mycoplasma infection reported.

Pathological changes

General changes: mainly in the respiratory tract, sometimes also appear in the fallopian tube. Changes in the respiratory tract are also varying severity. Slightly difficult to wipe sensation, nostrils, sinuses, trachea and lungs appear more viscous liquid or catarrhal secretions, tracheal wall edema. As the infection progresses, the balloon becomes turbid and the cystic exudates appear on the wall of the balloon, beginning like a bead and piling up in a serious manner. Inflammation of the infraorbital sinus, in the suborbital sinus showed sticky and cheese-like exudate. Sometimes pericarditis and pericoronitis changes, this time can often be isolated Escherichia coli. Joint symptoms occur, the joint swelling and swelling of the joint NIgH, synovial fluid increased, the beginning of clear and then cloudy, and finally was creamy consistency.

Histological changes: hypertrophy of the respiratory epithelial tissue hyperplasia, cilia loss. Subepithelium tissue lymphocytes, ganglion cells and plasma cell hyperplasia, and then gradually thickened. Lymphoid follicles in mononuclear cell aggregation, mucous gland hyperplasia. The tracheal mucus gland is long and narrowly stretched into the thickened mucosa. A large number of lung tissue mononuclear cells and heterophilic cell infiltration. Synovial cell surface proliferation, synovial capsule and adjacent tissue mononuclear cell infiltration, lymphoid follicle formation. Joint fluid can occur in a large number of heterophilic cells.