There are several different types of eye diseases that can affect birds. Some are quite problematic and may even be fatal. Some rare, but serious, bird eye diseases may be transmitted to humans.
Like all creatures that can see, birds are susceptible to a variety of conditions that may affect the health of their eyes. Two of the most serious avian infectious eye diseases are mycoplasmal conjunctivitis and psittacosis (sih-tuh-KAW-suhs). Scientists have found examples of mycoplasmal conjunctivitis in numerous types of birds, but since 1994 the disease has spread rapidly among house finches, leading to its nickname of "house finch eye disease." Psittacosis is so named because it is a common condition among domesticated fowl such as parrots (from the psittacines family) and turkeys. Some people refer to psittacosis as "parrot fever."
The symptoms of both types of eye diseases begin much like eye infections in humans. House finch eye disease begins as an infection caused by the bacterium Mycoplasma gallisepticum. The eyes of affected birds may exhibit redness, swelling and discharge. In some cases the eyes may swell shut completely. Psittacosis, caused by a bacterium called Chlamydophila psittaci, affects the digestive system as well as the eyes. In addition to eye discharge, symptoms may include poor appetite and diarrhea.
Both of these conditions can prove fatal to birds. Victims of house finch eye disease may become blind, rendering them vulnerable to predators and unable to feed themselves. Such birds usually die quickly after losing their eyesight. The rapid spread of the disease threatens the balance of bird populations in some areas. Psittacosis may also lead to blindness or death.
Danger to Humans
Mycoplasmal conjunctivitis poses little threat to humans. Psittacosis, however, can transfer quite easily to humans, usually through contact with infected birds or their droppings. Those who have frequent contact with domestic birds, such as pet shop or veterinary workers or bird owners, are most susceptible. In humans, the disease manifests symptoms similar to the flu. If left untreated, however, it can prove deadly. Since 1996, about 50 Americans per year have contracted psittacosis. Most received successful treatment with antibiotics.
The best way to limit the spread of bird eye infections is through observation and prevention. Citizens can report wild birds suspected of carrying any disease to Cornell University's FeederWatch Program, whose address is listed in the resource section below. The program tracks bird diseases for research and prevention. When encountering a bird that has possibly died from disease, humans should avoid direct contact with the carcass. Pet owners should keep cages clean and avoid build-up of bird droppings. A veterinarian should immediately examine any bird exhibiting symptoms of psittacosis. Humans suspected of infection should also seek immediate treatment.