1. The serious impact of pathogens
The anatomical lesions of poultry infected with duck source chicken bacteria include splenomegaly, liver bleeding, peritonitis, salpingitis, nephritis, follicular rupture, ovarian atrophy, ovarian inflammation, and egg drop into the abdominal cavity. Clinical symptoms include runny nose, fever, depression, cyanosis, anorexia, dehydration, brownish green diarrhea, exhaustion, uncertain mortality rate, decreased egg production, and delayed egg production. The decrease in egg production ranges from 8% to 40%.
There are relatively limited research reports on the specific identification of duck source chicken bacteria, and the methods widely used until now are based on biochemical testing to determine whether the bacteria can utilize certain sugars or substrates. Thus, a well-defined pattern map has been established for 24 different strains, and serological typing studies have also been attempted. The results indicate that even isolated strains from the same region have diverse serotype categories (similar to avian infectious rhinitis). Regarding the diagnosis of this bacterium, a PCR detection method specific for 16s rRNA of duck derived chicken bacilli has been established. Boehringer Ingelheim conducted some research aimed at determining the impact of duck derived chicken bacteria on chicken production systems. The test results showed that laying hens were more susceptible to this disease at 22-34 weeks of age, while broiler chickens were mainly infected at 6 weeks of age. The experiment also observed respiratory like diseases, uneven body weight in the chicken flock, exhaustion and other symptoms, with a mortality rate of over 8%.
2 Global distribution
Infection of chicken flocks with this bacterium can cause significant economic losses due to the need to take measures to control the disease, such as the use of antibiotics, personnel operations, and visible direct impacts on production indicators (egg production and weight). Appropriate biosafety measures and prevention methods can help prevent the occurrence of diseases related to duck derived chicken bacilli.
Chicken bacilli of duck origin exist in many countries or regions, including Mexico, Panama, the United States, Denmark, Germany, Australia, Taiwan, China, Japan, Nigeria, Israel, Syria, Norway, the United Kingdom, and Sweden. Therefore, chicken bacilli of duck origin are distributed globally.
3. Antimicrobial resistance
In terms of the pathogenic factors of this bacterium, studies have shown that several strains have antibiotic resistance, even strains isolated in areas where the use of antibiotics as growth promoters is prohibited also have this resistance. This result suggests the fact that duck derived chicken bacillus strains have an antibacterial resistance system, but it is not caused by continuous exposure to antibiotics. This poses obstacles to designing antibiotic treatment plans to control diseases. In addition, literature has reported a method for the bacterium to evade immune response, which includes a specific metalloprotease targeting avian immunoglobulin in the evasion immune response system. So far, the virulence factor of duck derived chicken bacteria that has been extensively studied is hemolysin GtxA, and its transmission mode in several clinical isolates has not been elucidated. The attempt to replicate clinical diseases by inoculating infected healthy chickens into the reproductive cavity and trachea was unsuccessful, as no avian like infectious diseases were observed. Intravenous vaccination has been proven to replicate clinical diseases, but the mode of transmission and transmission remains to be clarified. Due to the widespread distribution of this bacterium and its clinical and economic impact on commercial chicken flocks, we have reason to believe that it is extremely important to clarify the mechanisms of disease transmission and the factors that promote the spread and invasion of the pathogen from the upper respiratory tract, as well as to understand the immune response evasion system.
