Prevention and Control Methods and Technical Key Points for Duck Infectious Serositis
Duck infectious serositis, also known as duck septicemia Pasteurella disease, is a chronic or acute septicemic infectious disease that affects ducklings (goslings). It is characterized by fibrinous pericarditis, perihepatitis, airsacculitis and arthritis. With the rapid development of the @#@231@#@ industry and the expansion of trade in poultry products, the incidence of duck infectious serositis has been rising year by year, and it is prone to occur and difficult to treat, having become one of the important diseases restricting the rapid development of the duck farming industry. Controlling and eliminating this disease is of great significance for promoting the rapid development of the duck farming industry. Based on my own practical work experience, I will discuss my understanding of the prevention and control work for this disease.
Pathogen: The pathogen of this disease is duck septicemia Pasteurella, Gram-stain negative, with the bacterial cells being small bacilli, some oval in shape, with capsules; Wright's staining shows a few bacterial cells with bipolar staining. On chocolate agar plates, the colonies do not hemolyze and appear as small dewdrop-like colonies. It cannot grow on ordinary agar or MacConkey medium. The vast majority of duck septicemia Pasteurella survives on solid medium at 37°C or room temperature for no more than 3-4 days; at 4°C, broth cultures can be preserved for 2-3 weeks. At 55°C, it loses viability after 12-16 hours of culture. In water and litter, it can survive for 13 days and 27 days respectively.
Epidemiology: This disease occurs mostly at the turn of autumn and winter and at the turn of spring and summer. Under normal circumstances, it mainly occurs in ducklings and goslings aged 1-8 weeks. Ducklings aged 2-3 weeks are especially susceptible, while ducks over 8 weeks of age rarely develop the disease. Adult ducks rarely develop the disease but can carry the bacteria and become a source of infection. This disease is mainly transmitted through the respiratory tract or skin wounds, and can also be transmitted vertically through breeding eggs. Contaminated feed, drinking water and air are all important routes of transmission; excessive density in brooding houses, poor ventilation, dampness and malnutrition are all predisposing factors for the occurrence of this disease.
Symptoms: The incubation period of this disease is generally 1-3 days, sometimes up to 7 days. Young ducks develop the disease relatively acutely, often suddenly falling ill under stress conditions, and die quickly without obvious symptoms. Sick ducks with a longer course of disease show lethargy, depression, isolation from the flock, reduced or complete loss of appetite, head shaking and neck retraction, elevated body temperature, rapid breathing, discharge from the eyes and nose, contaminated eyes, weakness in both legs, ataxia; some show neurological symptoms, paroxysmal spasms, and pass yellow-green foul-smelling loose feces. A small number of sick ducks show arthritis symptoms such as lameness and inability to stand up. Ducklings aged 1-2 months show a subacute or chronic course, continuously calling, incoordination, sometimes circling, sometimes backing up, poor development, gradually emaciating, and dying from exhaustion. Due to differences in feeding and management conditions, the mortality rate varies greatly, generally 10%-30%, and can reach over 50 in high cases.
Pathological changes: The lesions in acute cases are systemic dehydration and enlargement of the liver and spleen. In cases with a longer course, there is fibrinous inflammatory exudation on the serosal surfaces. The main manifestations are pericarditis and pericardial effusion, with fibrinous exudate on the pericardial membrane; the liver is significantly larger than normal, appearing earth-yellow or grayish-brown, relatively brittle in texture, with a grayish-white or grayish-yellow fibrinous membrane covering its surface that is easily peeled off, presenting fibrinous perihepatitis and fibrinous airsacculitis; the posterior part of the abdominal air sacs shows yellowish-white caseous exudate, and some cases show salpingitis and arthritis.
Diagnosis: In veterinary clinical practice, a preliminary diagnosis can generally be made based on comprehensive analysis of epidemiology, clinical symptoms and pathological changes. If confirmation is needed, laboratory methods such as microscopic examination and bacterial culture can be used; during bacterial isolation and culture, blood culture medium can be used for culture and then inoculated onto differential medium for identification.
Prevention and control: This disease has a high incidence and is widespread, so comprehensive prevention and control measures must be adopted.
Strengthen feeding and management. Supply the duck flock with high-quality, comprehensive and sufficient feed, maintain reasonable environmental temperature, air humidity and rearing density, strengthen the ducks' exercise, replace litter in a timely manner, do a good job of ventilation and air exchange, and improve the ducks' physique.
Rational use of drugs. Sulfonamides, streptomycin, gentamicin, erythromycin, tetracycline and other drugs are all effective against duck septicemia Pasteurella, but due to the abuse of antibacterial drugs in recent years, bacterial resistance has been increasing. Therefore, when using drugs, it is best to conduct a drug sensitivity test first, use drugs in a targeted manner, and replace drugs in a timely manner to improve efficacy. In prevention and control, it is common to add sulfadimethylpyrimidine to the feed and feed it continuously for 3 days, with good results.
Do a good job of disinfection and vaccination. In order to prevent the occurrence and spread of the disease, regularly disinfect duck houses, feed troughs, water troughs and places where ducks frequently move around, and carry out immunization with inactivated duck septicemia Pasteurella vaccine.
Strict quarantine. Strengthen the supervision and management of goose and duck farms and hatcheries, and add necessary epidemic prevention equipment. Strictly control vaccination, disinfection and the supply of young stock, and do a good job of transport quarantine and market quarantine to prevent the occurrence and spread of the epidemic.