Pink eye is a commonly used term for conjunctivitis. Conjunctivitis is an inflammation of the conjunctiva, the outer layer of the eye and the inner surface of the eyelid.
Causes of Pink Eye
Conjunctivitis can be caused by bacterial or viral infection or develop as a response to allergy-causing agents, dust or smoke in the environment. Conjunctivitis is most commonly caused by a virus and it is known as viral conjunctivitis. Conjunctivitis induced by bacterial infection is known as bacterial conjunctivitis. Both viral and bacterial conjunctivitis are contagious. Conjunctivitis that develops due to allergic reaction is called allergic conjunctivitis and it is noninfectious.
Viral conjunctivitis is most commonly caused by adenovirus. Adenovirus is the type of virus that causes common cold so viral conjunctivitis often develops following an infection of upper respiratory tract. Viral conjunctivitis is common in children and it is highly contagious. This type of conjunctivitis initially affects one eye and after a couple of days spreads to the other eye. Viral conjunctivitis causes symptoms such as: itching and redness of the eyes, excessive tearing in the eyes, swollen eyelids and watery, mucus discharge. Runny nose, sore throat and sinus congestion can be present too. Symptoms of viral conjunctivitis can last between one to two weeks. Apart from adenovirus, viral conjunctivitis can be also caused by Herpes simplex virus, Varicella zoster virus and Molluscum contagiosum.
Bacterial conjunctivitis is most frequently caused by Staphylococci and Streptococci. This type of pink eye is followed by symptoms such as: eye pain, redness, swelling and heavy, yellow or greenish discharge. Sometimes, there may be crusting on the eyelids. Bacterial conjunctivitis can be also followed by common cold-like symptoms. This type of conjunctivitis can be sometimes caused by infection with Chlamydia and it can be transmitted sexually.
Pink eye Incubation PeriodThe incubation period for pink eye depends on the cause of the condition. Incubation period is amount of time between exposure to pathogen or allergen to the start of symptoms. Symptoms of pink eye do not develop immediately after contracting infectious agent. Symptoms of viral conjunctivitis typically start to appear 12 hours to 3 days after exposure to virus. Incubation period for bacterial conjunctivitis is between 1 and 3 days. Even though viral and bacterial conjunctivitis are contagious, an infected person cannot transmit the disease during the incubation period. A person infected by bacterial conjunctivitis becomes contagious the moment the symptoms appear until one day after beginning of antibiotic treatment. Viral conjunctivitis is contagious up to two weeks from the moment symptoms develop.