Conjunctivitis, commonly known as pink eye, is an inflammation of the conjunctiva, the thin membrane covering the white part of the eyeball and the inner surface of the eyelids. When inflamed, blood vessels dilate, causing the characteristic redness and swelling. This irritation often leads to symptoms like excessive blinking, discomfort, and discharge that can range from clear and watery to thick and pus-like.
Is Feline Conjunctivitis Zoonotic?
The short answer is that, in specific instances, pink eye can transfer from a cat to a human, though the risk is generally low. Most causes of pink eye in cats are species-specific, meaning the infectious agents are adapted to cats and do not easily cross to humans. For example, Feline Herpesvirus-1, a common cause of cat conjunctivitis, is not transmissible to people.
The primary concern for cross-species transmission lies with certain bacterial causes. The bacterium Chlamydia felis is a known zoonotic pathogen that can be spread from an infected cat to a human through direct contact with the cat’s infected eye discharge or contaminated objects. While rare, human infection with C. felis can cause follicular keratoconjunctivitis, typically affecting people in close contact with an infected cat or those who are immunocompromised.
Common Causes of Pink Eye in Cats
Conjunctivitis in cats is categorized into infectious and non-infectious causes, with infectious agents being the most frequent culprits. Viral infections are the most common cause, particularly Feline Herpesvirus-1 (FHV-1), a widespread virus that can remain dormant in the cat’s nervous system and reactivate during periods of stress. Another common viral agent is Feline Calicivirus.
Bacterial infections are also a significant factor, either as a primary cause or as a secondary infection following a viral illness. The most notable bacterium is Chlamydia felis, which is responsible for up to 30% of chronic conjunctivitis cases and is the agent with zoonotic potential. Other bacteria frequently isolated include Mycoplasma species, which can also cause significant inflammation and discharge.
Non-infectious causes of feline pink eye include environmental factors and underlying health conditions. Allergies to substances like dust, pollen, and mold can trigger inflammation in the eye. Physical irritants, such as foreign bodies like stray hairs or dust particles, as well as trauma to the eye, can also lead to conjunctivitis.
Reducing the Risk of Transmission
Minimizing the risk of transmission requires focused attention on hygiene and prompt veterinary care. Rigorous hand washing is the most important preventative measure, especially after administering eye drops or touching the cat’s face, bedding, or toys, as infectious agents are often spread by contaminated hands coming into contact with a person’s own eyes.
Infected cats should have separate bedding and towels, which should be washed frequently in hot water to kill lingering bacteria. Surfaces the cat frequently touches should be disinfected regularly to prevent the spread of ocular discharge. Seeking immediate veterinary treatment for a cat showing signs of conjunctivitis will shorten the infectious period and reduce the risk of cross-species spread.