Illness on Pandora?

[Raiden]

There's got to be some endo/ectoparasites, bacteria, and viruses.

It would be foolish to say that they have organisms like roundworms, flukes, parasitic protists and the like, because Pandora has its own phylogenetic tree.

It wouldn't be too far-fetched to say the same about bacteria and viruses, because they are so simple that something like them would have to have been one of the first life forms to exist on Pandora (and viruses aren't really organisms anyway).

As for the Na'vi, they'd have to get sick occasionally, but like some people said, pandemic outbreaks would only occur if something disturbed the ecosystem enough to allow that to happen/released a dormant contagion from underground/the Na'vi became overpopulated.

Since they are generally in balance with the ecosystem, this probably doesn't happen very often. If you look back at large dieoffs of humans from pandemics, it almost always had to do with something that we had done to allow the spread of the contagion responsible.

But, despite Pandora being beautiful, there has to be something ugly somewhere. Personally, I wouldn't mind seeing JC make some nasty worm or giant predatory insect or something to balance. I don't really think anything in nature is truly ugly anyway.