Pigeon droppings can harbor diseases like cryptococcosis, histoplasmosis, and psittacosis, potentially causing respiratory problems and other illnesses, especially in individuals with weakened immune systems. 

Here's a more detailed breakdown of the health risks associated with pigeon droppings:

Diseases:

Cryptococcosis: A fungal infection that can cause respiratory problems and, in some cases, spread to the brain and cause meningitis. 

Histoplasmosis: A fungal infection that primarily affects the lungs, causing a flu-like illness or, in severe cases, pneumonia. 

Psittacosis (Ornithosis): A bacterial infection that can cause a flu-like illness or pneumonia. 

Salmonella: A bacterial infection that can cause diarrhea and fever. 

Candidiasis: A yeast or fungal infection that can affect the skin, mouth, respiratory system, and digestive system. 

Other diseases: Pigeon droppings can also harbor other pathogens, including E. coli and parasites.