We say "have conjunctivitis". If you are talking about diseases or conditions, the article "a" is not necessary.
We say "have conjunctivitis". If you are talking about diseases or conditions, the article "a" is not necessary.
If you have conjunctivitis, you might also have puffy eyes.
Having conjunctivitis can be contagious.
We also say "have pink eye" (not "a pink eye").
My sister has pink eye.
Follow the same strategy with the expressions "treat conjunctivitis", "cause conjunctivitis", "develop conjunctivitis", "prevent conjunctivitis", "diagnose conjunctivitis", etc.
It can irritate the eye and cause conjunctivitis.
Avoid touching your infected eye to prevent conjunctivitis.
Your doctor should be able to diagnose conjunctivitis by examining your eyes.
But you can use a possessive pronoun (my, your, his, her, our, your, their).
If your conjunctivitis was caused by acid, rinse the eyes with lots of water and call your doctor.
A partial list of diseases that do not take the indefinite article (a/an) can be found below: