Fear of wild rats as carriers of disease is embedded within our culture. Surprisingly little is actually known about parasites in wild rat populations. In recent studies aimed to rectify this omission, farms in England and Wales were surveyed to identify parasite species present in the rat populations. Rats were found to be infected with numerous zoonotic parasites, including cryptosporidium, pasteurella [correction of pasturella], listeria, yersinia, coxiella, and hantavirus. These findings suggest that wild brown rats represent a potential risk to the health of humans and domestic animals.