Bacterial Diseases

Major bacterial diseases of ducks are Riemerella anatipestifer infection, avian cholera, colibacillosis, and salmonellosis. Occasionally, erysipelas, chlamydiosis, streptococcosis, staphylococcosis, boltulism, and clostridial infections have been reported in ducks.

Riemerella anatipestifer (previously called Pasteurella anatipestifer) infection is a major health problem of ducklings.[4] It causes serious economic losses to the duck industry due to mortality, weight reduction, and condemnation. Ducklings, one to 10 weeks of age, are highly susceptible. Affected ducklings exhibit listlessness, incoordination, convulsions of head and neck, ataxia, and torticollis. At least 20 different serotypes of Riemerella anatipestifer have been reported worldwide; no significant cross-protection has been observed between different serotypes. Diagnosis should be made based on history, signs, lesions, bacterial isolation, and identification. The disease is transmitted through the respiratory route and cuts in the skin. Treatment with novobiocin, penicillin, enrofloxacin, and sulfadimethoxine-ormetoprim is effective to some extent. Live and inactivated vaccines have been used successfully for immunization of ducklings

(Table 1). Because there is little or no cross-protection between different serotypes, an ideal vaccine should be effective against predominant serotypes to provide broad-spectrum protection.

Avian cholera is a contagious septicemic disease of ducks and other poultry caused by Pasteurella multocida. Birds show anorexia, mucus discharge from the mouth, and diarrhea. Mature birds are more susceptible than young ducklings. Bacterial isolation and identification should confirm diagnosis. Treatment with antibiotics and sulfa drugs is very effective. Killed bacterial vaccines have been used for prevention.

Collibacillosis is a common infection of all poultry including ducks. It is caused by Escherichia coli. E. coli is responsible for a variety of health problems in ducks and other poultry. It causes low hatchability, due to embryonic mortality, and omphalitis in young ducklings, due to yolk sac infection. Colisepticemia usually occurs in older and breeder ducks. The disease often occurs due to unsanitary conditions. Isolation and identification of the causative bacteria are critical to confirm diagnosis. Chlortetracy-cline, enrofloxacin, and sulfadimethoxine-ormetoprim have been shown to reduce mortality. Killed vaccines have also been used for prevention.

Salmonellosis or paratyphoid infections in ducks and other poultry are caused by various serotypes of salmonella. Predominant serotypes isolated from ducks are Salmonella enteritidis and Salmonella typhimurium.[5] The disease is contracted by ingestion of contaminated feed or water and by vertical transmission through the eggs. Young ducklings under three weeks of age suffer from acute intestinal infection. Treatment with chlortetracycline or sulfadimethoxine-ormetoprim in feed for the first two weeks of age is practiced on most duck farms. Serological monitoring of breeding flocks through testing and elimination of carriers is highly recommended for control. Proper management of breeder ducks along with sanitation of hatching eggs and incubators is also helpful in reducing shell surface contamination.

Aspergillosis caused by Aspergillus fumigatus can result in high mortality in young ducklings. Most often, the source of infection is contaminated litter or feed. Contamination of hatching eggs and the hatchery environment has been reported to cause embryonic mortality and hatchability problems. Elimination of the source of infection and proper sanitation of hatching eggs are recommended.

Ducklings are also highly susceptible to aflatoxins that may be present in feed grains, especially corn. Aflatox-icosis may cause low productivity, higher mortality, and immunosuppression that may lower immune response to vaccines. Feed grains should be tested for aflatoxins before inclusion in duck rations.

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