How Do You Get Pink Eye?
Pink eye is known medically as conjunctivitis. Conjunctivitis is inflammation of the conjunctiva, which is the thin piece of tissue that covers the whites of the eyes and the inner eyelids. People diagnosed with the condition may wonder how they got pink eye.
Most cases are caused by a virus -- in particular, adenovirus. This is the same virus that often causes the common cold, which is why viral conjunctivitis often occurs following a recent upper respiratory tract infection.
The allergens that cause both seasonal and year-round allergy symptoms can also cause pink eye (known as allergic conjunctivitis). In fact, it is estimated that up to 20 percent of people each year suffer from allergic conjunctivitis. About half of these people also suffer from other types of allergic disease, including allergic rhinitis, atopic dermatitis, and asthma.
Pink eye can also be caused by an infection with bacteria. The most common causes of bacterial conjunctivitis are Staphylococcus aureus (staph infection), Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis. The bacteria that cause gonorrhea (Neisseria gonorrhoeae) and chlamydia (Chlamydia trachomatis) can also cause bacterial conjunctivitis. They are usually spread from the genitalia of an infected person to the hands and then to the eyes.
(Click Pink Eye Causes for more information on how you can get pink eye, the specific symptoms of each type of conjunctivitis, and what other conditions can lead to pink eye.)