Yes. Often referred to as the "flying rat", pigeons carry over 60 different bacterial diseases, viruses and funguses transmittable to humans and pets. Bird nests and materials can also host parasites, like the common bird mite. Some of the diseases most commonly spread by pigeons include Salmonella, Meningitis, West Nile Virus, Ecoli, Avian Flu (H5N1), and Histoplasmosis.