Feline Herpes virus (FHV-1)
Feline Herpes virus (FHV-1) is very common in the worldwide cat population, with exposure rates greater than 90% reported. It causes cat 'flu, and is also one of the most common causes of eye problems in cats.
More than 80% of cats exposed to FHV-1 become lifelong carriers, and around half of these cats will develop recurrent problems, which typically develop during periods of stress. This is called recrudescent disease.