Poultry diseases occur in poultry, which are domesticated birds kept for their meat, eggs or feathers.
Viral diseases
thumb|alt=Side view of a yellow chick leaning forward, with its eye closed, beak wide open, and feathers in a disheveled state.|8 day old chick with difficulty breathing, due to an Avian influenza infection.
- Avian infectious bronchitis, caused by a strain of Avian coronavirus previously known as infectious bronchitis virus
- Avian infectious laryngotracheitis, caused by Gallid alphaherpesvirus 1
- Avian influenza, caused by Avian influenza virus
- Duck plague, caused by Anatid alphaherpesvirus 1
- Chicken infectious anemia, caused by Chicken anaemia virus
- Epidemic tremor, caused by Tremovirus
- Fowlpox, caused by viruses in the genus Avipoxvirus
- Infectious bursal disease (IBD), also known Gumboro disease, caused by Infectious bursal disease virus
- Lymphoid leukosis caused by avian sarcoma leukosis virus
- Marek's disease
- Newcastle disease
- Viral arthritis, caused by Avian reovirus
Parasitic diseases
thumb|Infestation of Echidnophaga gillinacea fleas on the comb and around the eye of a chicken
- Scaly leg, caused by the mite Knemidocoptes mutans
- Infestation by Dermanyssus gallinae, the red poultry mite
- Infestation by Echidnophaga gallinacea, the sticktight flea
Bacterial diseases
- Colibacillosis in poultry
- Infectious coryza in chickens
- Ornithobacterium rhinotracheale
- Pullorum disease
- Riemerella anatipestifer
- Salmonellosis in poultry
- Staphylococcal infection in poultry
- Streptococcal infection in poultry
- Omphalitis in chicks (mushy chick disease)
- Mycoplasmosis
- Fowl cholera
- Campylobacteriosis
- Pseudomonas
- Ornithobacteriosis
Protozoal diseases
- Histomoniasis (blackhead disease), caused by Histomonas meleagridis
- Coccidiosis
- Trichomonas gallinae
Fungal diseases
- Ergotism, which occurs when poultry feed is contaminated with toxic alkaloids produced by fungi of the genus Claviceps
- Aspergillosis, a non-contagious disease caused when birds inhale Aspergillus spores that cause breathing to be hard for the bird
- Ringworm
