What are the prevention and control methods for duck infectious serositis?
Duck infectious serositis, also known as duck pasteurellosis (Riemerella anatipestifer infection), is a chronic or acute septicemic infectious disease affecting ducklings (and goslings). It is characterized by fibrinous pericarditis, perihepatitis, airsacculitis and arthritis. With the rapid development of the @#@231@#@ industry and the expansion of poultry product trade, 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 industry. Controlling and eliminating this disease is of great significance for promoting the rapid development of the duck industry. Based on my own practical work experience, I would like to share my insights on the prevention and control of this disease.
Pathogen: The pathogen of this disease is Riemerella anatipestifer (Pasteurella anatipestifer), which is Gram-negative. The bacterial cells are small bacilli, some oval-shaped, with capsules. Wright's staining reveals a few bacterial cells with bipolar staining. On chocolate agar plates, the colonies are non-hemolytic and appear as small dewdrop-like colonies. It cannot grow on ordinary agar or MacConkey medium. The vast majority of Riemerella anatipestifer survives on solid medium at 37°C or room temperature for no more than 3-4 days, and broth cultures can be preserved for 2-3 weeks at 4°C. At 55°C, it loses viability after 12-16 hours of culture. It can survive in water and bedding for 13 days and 27 days respectively.
Epidemiology: This disease mostly occurs at the turn of autumn and winter and at the turn of spring and summer. Under normal circumstances, it mainly affects ducklings and goslings aged 1-8 weeks. Ducklings aged 2-3 weeks are most susceptible, and 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 stocking 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 acutely, often suddenly 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 lost appetite, head shaking and neck retraction, elevated body temperature, rapid breathing, discharge from the eyes and nose, contaminated eyes, weakness in both legs, ataxia, and some show neurological symptoms with 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. Ducklings aged 1-2 months show a subacute or chronic course, with continuous calling, ataxia, sometimes circling, sometimes backing up, poor development, gradual emaciation, and death from exhaustion. Due to differences in feeding and management conditions, the mortality rate varies greatly, generally 10%-30%, and can reach over 50% in severe cases.
Pathological changes: The lesions in acute cases include systemic dehydration and enlargement of the liver and spleen. In cases with a longer course, there is fibrinous inflammatory exudate on serous membranes. The main manifestations are pericarditis and pericardial effusion, with fibrinous exudate on the pericardium; the liver is significantly larger than normal, presenting a earthy yellow or grayish-brown color, relatively fragile in texture, with a layer of grayish-white or grayish-yellow fibrinous membrane covering its surface that is easily peeled off; fibrinous perihepatitis and fibrinous airsacculitis occur, with yellowish-white caseous exudate appearing in the posterior part of the abdominal air sacs, and some cases develop 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. For confirmation, laboratory methods such as microscopic examination and bacterial culture can be used. For bacterial isolation and culture, blood culture medium can be used for cultivation and then inoculated onto differential media for identification.
Prevention and control: This disease has a high incidence and wide prevalence, so comprehensive prevention and control measures must be adopted.
Strengthen feeding and management. Provide the duck flock with high-quality, comprehensive and sufficient feed, maintain reasonable environmental temperature, air humidity and stocking density, enhance the movement of ducks, replace bedding in a timely manner, do a good job in ventilation, and improve the physique of the ducks.
Rational drug use. Sulfonamides, streptomycin, gentamicin, erythromycin, chloramphenicol, tetracycline and other drugs are all effective against Riemerella anatipestifer. However, 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 sulfadimidine to the feed and feed continuously for 3 days for a good effect. Do a good job in disinfection and vaccination. In order to prevent the occurrence and spread of the disease, regular disinfection should be carried out on duck houses, feed troughs, water troughs and places where ducks frequently move, and immunization with inactivated Riemerella anatipestifer vaccine should be carried out. 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 breeding stock, and do a good job in transport quarantine and market quarantine to prevent the occurrence and spread of the epidemic.