In Connecticut alone, cats are the third largest carriers of rabies. Nation wide, they are the domestic animal most frequently reported to have rabies. They may transmit the human disease toxoplasmosis. Fleas and well as tapeworms may present problems. Cat-scratch fever is a danger.
Feral cats congregate in stairwells in cities and leave objectionable odor.
They have eliminated certain bird species on islands. Coleman et al. Thirty percent of households have cats. Coleman et al. A mating pair and their offspring can produce 600 cats in two years.