Health hazards posed by feral pigeons.

A comprehensive literature search of epidemiological studies and reports of transmissions of disease from feral pigeons to humans was performed. There were 176 documented transmissions of illness from feral pigeons to humans reported between 1941 and 2003. Feral pigeons harbored 60 different human pathogenic organisms, but only seven were transmitted to humans. Aerosol transmission accounted for 99.4% of incidents. There was a single report of transmission of Salmonella enterica serotype Kiambu to humans from feral pigeons, and no reports of transmission of Campylobacter spp. The most commonly transmitted pathogens continue to be Chlamydophila psittaci and Cryptococcus neoformans. Although feral pigeons pose sporadic health risks to humans, the risk is very low, even for humans involved in occupations that bring them into close contact with nesting sites. In sharp contrast, the immunocompromised patient may have a nearly 1000-fold greater risk of acquiring mycotic disease from feral pigeons and their excreta than does the general population.