Avibacterium paragallinarum

Avibacterium paragallinarum is a gram-negative, rod-shaped bacterium which was previously called Haemophilus paragallinarum. Avibacterium is a genus within the family Pasteurellaceae which is a bacterium of birds.

Disease conditions associated with this genus are all linked to chickens and include infectious coryza (caused by A. paragallinarum), valvular endocarditis and septicemia (caused by A. endocarditidis), and a chronic fowl cholera-like condition (caused by A. gallinarum).

Although all species of Avibacterium are routinely found in chickens with upper respiratory tract infections, only A. paragallinarum is regarded as a primary pathogen and resulting in infectious coryza in chickens.

Transmission: The main reservoirs of infection for A. paragallinarum are chronic or apparently healthy carrier birds. Once introduced into a flock, A. paragallinarum is spread rapidly via direct or indirect contact with infected birds, through ingestion of contaminated feed or water, and by aerosols. Susceptible birds exposed to infected birds may show signs of the disease within 24-72 hours. Chickens who have recovered can become carriers, shedding the bacterium when stressed.

Survival in the Environment: A. paragallinarum is not a particularly resistant bacterium and does not survive longer than 4-5 hours in the environment outside a host. It is destroyed by common household disinfectants, desiccation, and direct exposure to sunlight.



  • Order: Pasteurellales
  • Family: Pasteurellaceae
  • Genus: Avibacterium


  • chickens