Illness on Pandora?

[Ashen Key]

I came across something - and I really can't remember WHERE or what it was - that said that on Pandora, there are few (if any) illnesses and diseases on Pandora.

Can anyone else either confirm or deny this? If not, what are your thoughts?

For example, I can see the Na'vi refusal of the RDA's offer of medicine coming from two places - either they don't accept it because they believe in the will of Eywa, or they simply don't have the need like similar-level humans would.

EDIT: As clarification, I mean Pandoran illnesses for Pandoran life, not human diseases.