There are several human diseases caused by contact with bird droppings. This is becoming a problem especially in cities with large pigeon populations. Buildings provide ideal nesting and roosting sites for pigeon flocks. These areas very quickly become fouled with excreta, and often this is in areas not accessible to normal cleaning processes. It is essential that this is addressed by building managers and health officials.

Histoplasmosis is a disease caused by a fungus, which grows in pigeon droppings. It also grows in soils and is found throughout the world. When cleaning droppings a person may breathe in some of the fungus, which in cases of high exposure can cause infection. Common activities, such as cleaning of windowsills, will not result in high exposures.

Symptoms of histoplasmosis begin to appear about 10 days after initial infection.  This includes fatigue, fever, and chest pains. Most people, however, do not show any symptoms. Those with compromised immune systems such as cancer patients or people living with HIV/AIDS are generally more at risk of developing histoplasmosis. The disease cannot be transmitted from person to person.

Cryptococcosis is another fungal disease associated with pigeon droppings and also grows in soils throughout the world. It is unlikely that healthy people will become infected even at high levels of exposure. A major risk factor for infection is a compromised immune system. According to the US Centers for Disease Control (CDC), nearly 85 percent of cryptococcosis patients are HIV-positive.

Psittacosis (also known as Ornithosis or Parrot Fever) is a rare infectious disease that mainly affects parrots and parrot-like birds. This includes cockatiels, and parakeets, but may also affect other birds, such as pigeons. When bird droppings dry and become airborne people may inhale them and get sick.

In humans, this bacterial disease is characterized by: fatigue, fever, headache, rash, chills, and sometimes pneumonia. Symptoms develop about 10 days after exposure. Psittacosis can be treated with a common antibiotic.

Those at greatest risk include bird owners, pet shop employees, veterinarians, and people with compromised immune systems. No person-to-person cases have ever been reported.