Domestic chickens can transmit diseases to humans in two ways. The first and the most common way is for a sick chicken or a sick chicken's faeces to come into contact with a person, usually a caretaker or a veterinarian. The second way is for a disease to reside in a sick chicken's eggs. When a person eats infected eggs, then she can also get sick.
Commonly known as "bird flu," avian influenza is the most serious chicken-to-human disease known, because people do not have immunity to it. People contract this disease through contact with live, sick chickens.
According to the University of Florida, avian tuberculosis is caused by bacteria in food. The only way a person can get it is to come in contact with the faeces of a sick bird.
The most common chicken-to-human disease is salmonella. Chickens get it by eating contaminated food. People can get it by eating the eggs of sick chickens or coming into contact with their faeces.
According to the University of Florida, rarely do chickens get chlamydiosis, arizonosis or colibaciliosis. However, when they do, these diseases can be transmitted to people by contact with the faeces of infected chickens, although arizonosis can also be found in the eggs of infected chickens.
Although named "chickenpox," chickens can't actually get chickenpox, so they can't transmit it to people.