When domesticated cats are lost or abandoned by their owners they learn to live on their own. They often become feral, and if they have not been spayed or neutered, they'll produce multiple litters of feral kittens. Since these cats live outdoors and are usually unvaccinated, infectious diseases and parasites can spread among them. If you’re interacting with a feral cat, take precautions to ensure your indoor kitties stay healthy.
Feline Leukemia Virus
The feline leukemia virus (FeLV) is a deadly virus that can spread quickly through feral colonies. It causes cancer and various immune deficiencies. It’s spread through saliva, nasal discharge, urine, feces and milk from lactating females. It’s short-lived outside the body, usually only viable for a few hours. Although rarely is FeLV passed by indirect contact to an indoor cat, if there’s saliva or other bodily fluids on a feral’s fur, the possibility does exist. If you’re feeding a stray, never share bowls or bedding with your indoor cat, and wash your hands after contact with one and prior to another.
Fleas and ear mites are often found on untreated outdoor cats. A person’s clothes can transport them indoors. Ear mites typically like to stay within the ears of their host, but they can be dislodged when a cat scratches or shakes his head. Fleas are hardy and persistent pests that will jump from host to host. When interacting with a stray, it's best to keep your indoor kitties on monthly flea preventive. Certain brands also help prevent ear mites.
Feline Upper Respiratory Infection
Upper respiratory infections in cats spread as quickly and easily as colds do in humans. The virus can be airborne, or transmitted through discharge from the nose or eyes. If an infected stray rubs against your clothes or hands, the virus can easily be transmitted to your indoor cat. Upper respiratory infections typically cause sneezing, congestion and conjunctivitis, an inflammation of the eye membranes. As a viral infection, it has to run its course. However, your veterinarian may prescribe antibiotics to prevent secondary bacterial infections. If left untreated, it may become pneumonia.
Ringworm is a highly contagious fungal infection spread through direct or indirect contact. Ringworm spores are extremely resilient, and they can survive in the environment for more than a year in bedding, dishes and clothing. Ringworm causes irritated circular patches of hair loss that typically appear on the ears, head and forelimbs of cats. Humans are also susceptible to this fungus. In healthy animals and people, ringworm typically responds well to antifungal medications. However, if left untreated, more serious infections may develop.