Pigeons, commonly found in the UK, can carry several diseases, including viral encephalitis, E. coli, salmonella, and cryptococcal meningitis, which can pose health risks to humans, particularly when in contact with their droppings. Effective measures, such as bird netting, are available to prevent pigeon nesting without harming them, as they are a protected species. It's important to maintain cleanliness and awareness when in proximity to pigeons to reduce the risk of disease transmission.