Conjunctivitis, commonly known as pink eye, is an inflammation of the conjunctiva, the thin membrane covering the inner eyelids and the white part of the eye. In both cats and humans, this condition causes redness, swelling, and discharge that can range from watery to thick. The underlying causes of pink eye vary significantly between species, which influences the likelihood of transmission. The primary concern is whether infectious agents from a cat’s eye irritation can successfully jump the species barrier to cause human illness.
The Specific Agents That Can Cross Species
The majority of conjunctivitis cases in cats are caused by pathogens highly adapted to the feline body that pose no threat to people. Feline Herpesvirus-1 (FHV-1) is the most common infectious cause of pink eye in cats, often leading to recurrent or chronic infections. This virus, along with Feline Calicivirus, is species-specific and cannot infect human hosts.
However, there are bacterial exceptions that can potentially cross from a cat to a person. Chlamydia felis is a bacterium that frequently causes conjunctivitis in cats, especially in young or group-housed animals. This organism is zoonotic, meaning it can be shared between animals and humans. While rare, human cases of follicular conjunctivitis have been linked to exposure to infected pet cats.
How Transmission Occurs Between Cats and People
Transmission of zoonotic agents, such as Chlamydia felis, from a cat to a human is rare. Since the bacteria do not survive well outside the feline host, infection requires close physical contact. The most common pathway involves direct contact with the infected cat’s ocular or nasal discharge. Transmission occurs when a person handles a sick cat, touches the discharge, and then touches their own eyes or mouth without washing their hands.
Indirect transmission can occur through contaminated objects, known as fomites. Items like bedding, towels, or grooming tools that have contacted the cat’s eye discharge can harbor the bacteria briefly. The risk of contracting the infection is highest during close, prolonged contact with a cat actively shedding the organism. Individuals with compromised immune systems face an increased risk compared to the general population.
Chlamydia felis is also shed in the cat’s feces, introducing a potential fecal-oral route of transmission. Contact with a contaminated litter box, followed by poor hand hygiene, can be a source of exposure. However, most human pink eye cases are acquired through person-to-person spread of human viruses or bacteria.
Simple Prevention Measures
Simple hygiene practices are effective in eliminating the risk of contracting pink eye from a cat. The most important action is to rigorously wash your hands with soap and water after handling a cat with eye discharge. This is especially important after administering medication or cleaning the cat’s face, as handwashing removes infectious discharge transferred from the cat.
Avoid touching or rubbing your own eyes after interacting with a sick pet. Also, prevent the cat from rubbing its face on yours or on frequently touched surfaces. Prompt treatment of the cat’s underlying condition, as directed by a veterinarian, is a primary preventative measure. Reducing the cat’s infectious period directly reduces the time the pathogen is shed into the environment.
Regularly clean and disinfect the cat’s bedding, food and water bowls, and any surfaces the cat uses while symptomatic. Use separate towels and washcloths for the cat, washing these items in hot water to limit the spread of potential zoonotic agents.