- Vaccination is an essential part of the disease control programme. Each bird owner should assess the risk of infectious agents gaining entry to the farm.
- There may already be infectious agents on the farm either carried by wild birds, older birds or remaining dormant in the environment. Disease virus and fowl pox virus can live in a poultry shed for many months or years and re-infect chicken in that environment.
- Some disease agents can spread through the air. These include the infectious bronchis virus, Newcastle disease virus, and fowl pox virus, which can be spread by mosquitoes. Rats and mice can spread fowl cholera from nearby farms.
- Some disease agents are egg borne and may be introduced when the farmer purchases day-old chicks or pullets from another farmer or can be passed from generation to generation within a flock.
- Examples of eggs-borne diseases include avian mycoplasmosis, avian leucosis, avian encephalomyelitis and salmonellosis. Inquiries as to the disease status of the parent flocks should be made to the breeding farm.
- Older pullets could already be carrying infections coryza, infections laryngotracheitis and Marek’s disease, unless they have been correctly vaccinated.