Chlamydia is not particularly common in the average pet cat but can be a significant problem in cats in close contact. It is very easily spread from cat to cat. It is rarely fatal, but can be a real problem because the symptoms may be very difficult to clear up. If your kitten has permanently runny or sore eyes with a yellowish discharge they may be suffering from chlamydia infection. This is a bacterial infection which is often mild but occasionally is more severe. If you cat has any eye problems you should make an appointment to see your vet - it may be that there is an underlying infection which can cause permanent damage if left untreated.