The main measure used to control disease in commercially-reared poultry is biosecurity programs, which are procedures put in place to stop diseases reaching poultry and farmyards while also stopping the spread of infection from diseased poultry. Biosecurity programs are the most effective, as spreads are often caused by infected farm equipment or workers in close contact with poultry.
Using biosecurity methods, which can involve processes such as cleaning boots in antibacterial wash after contact with poultry, can drastically reduce the risk and propagation of avian-related diseases. However, there are some exceptions. Some diseases can penetrate eggshells and thus are not contained by biosecurity measures. Salmonella is one example of such a disease.
Transmission through machinery, equipment and personnel are by far the greatest problems. Other forms of transmission, such as through air, are generally not a major risk, so they do not need to be factored in to a biosecurity program.
Serology is another line of defense against diseases in poultry. This practice involves taking blood samples from various flocks and testing them for viruses or infection levels.
While biosecurity can sometimes be an expensive solution, especially for larger, industrial-scale farms, reliance on drugs and antibiotics is not an effective way to combat disease. Most biosecurity programs can reduce or entirely eliminate infection rates in a flock.