The incubation time for bacterial conjunctivitis is a few days. In viral cases, incubation can be up to a week. Bacterial conjunctivitis lasts about a week. Viral conjunctivitis and the resulting inflammation can last as long as 2 weeks. A child can become infected by touching someone with the disease who has touched the infected eye.
Bacterial cases are contagious as soon as symptoms appear.
The child will remain contagious for as long as there is a discharge from the eye and until medical treatment begins. Viral conjunctivitis is usually contagious prior to the onset of symptoms and for as long as symptoms last. It can be difficult for a parent to know if the cause of the conjunctivitis is bacterial or viral. Additionally, the doctor will need to look inside your child's ears to see if a middle ear infection is present. Medical treatment does decrease the time that the disease is contagious.