Cryptococcosis (Cryptococcus neoformans)
Cryptococcosis is a fungus whose spores can be found in soil contaminated with pigeon droppings. Signs of cryptococcosis are rare in birds.
People get cryptococcosis by breathing in contaminated dust or getting it in open wounds. In humans, symptoms resemble pneumonia and include shortness of breath, coughing, and fever. Skin infections involving Cryptococcus can also occur. Infants, elderly persons, and those with weakened immune systems can have more serious infections.
Histoplasmosis (Histoplasma capsulatum)
Histoplasmosis is a fungal disease that is spread to people when they breathe in dust from pigeon or bat droppings. Birds do not get sick from exposure to histoplasmosis.
Very few people become infected with histoplasmosis. People who do become ill tend to develop pneumonia-like symptoms within 1–3 weeks of exposure: fever, chest pains, and a dry or nonproductive cough. Infants, older people, and those with weakened immune systems are more susceptible to the fungus and might develop more serious illness.
Mycobacterium avium complex (MAC, Avian Tuberculosis)
MAC is a bacterial disease spread to people from birds and other animals through the environment. Affected birds can become depressed, thin, and weak, and might have diarrhea. Birds carrying this disease shed large amounts of the bacteria into the environment.
Experts believe that people get MAC through exposure to the bacteria in the environment, though it is not clear exactly how the bacteria are transmitted. This disease primarily affects people with a weak immune system. Affected people might lose weight, have abdominal pain or diarrhea, and be anemic or feel tired.
Parrot Fever (Psittacosis; Chlamydiophila psittaci)
Parrot fever is a bacterial disease that people can get after accidentally breathing in secretions of infected psittacine birds, including parrots and parakeets, or poultry and wild birds. Birds might or might not show signs of illness from parrot fever.
People who become sick with parrot fever might have fever, chills, headache, muscle aches, difficulty breathing, and a dry cough. Symptoms usually begin 5–14 days after exposure but can take years to appear. Infants, the elderly, and those with weakened immune systems are more susceptible to parrot fever and might develop more serious illness.