Have you even pondered about whether Force users...

[Greywolf]

...are immune (or at least quite resistant) to diseases?
(Having a cold leads to those ideas ...)

My guess is the force probably would protect your health, right?

[For Tyeth]

The Jedi have been described as being able to "Force Heal" themselves after sustaining injuries, though I'm not sure if it has been written out of canon now. Luke used the ability to heal himself (injuries from Palpatine's lightning attack in ROTJ) in the novel The Truce at Bakura, and IIRC there was mention in the Bane Trilogy books too that Jedi could heal themselves but Sith could not (Bane was trying to remove the Orbalisks at his camp on Ambra). It was a slow process however. Not sure about common colds or allergies though.

Strangely enough in my backstory I wrote for myself For Tyeth gets badly injured in an explosion. He was showered with sparks of Cortosis which poisoned him but the Force helps him to survive, however he has to live with Cortosis poisoning causing scarred flaking wounds (I wrote this to help explain my real life appearance caused by Psoriasis).

[Greywolf]

The Jedi have been described as being able to "Force Heal" themselves after sustaining injuries....

That was my initial thought, too. Injuries usually happen quite suddenly, though, therefore the need for a 'dedicated' "Force Heal". Perhaps for 'slower' dangers like a disease the (light-side) Force user constantly & subconsciously uses the Force to heal himself?
On the other hand I think I've read somewhere (EU-related) that Sith alcemy could create really aweful diseases which were able to kill Jedi, too, so probably that protection is not 100%...

[For Tyeth]

There is mention of toxins created by Darth Maladi that could kill everyone in the Legends comics by Dark Horse. She created a toxin called Omega Red I believe when she was held prisoner by Roan Fel in the battle against Darth Krayt. (I think there was a double cross and the toxin would have killed everyone except the Sith)
I will look into the matter further and see what information I can find.

[ithekro]

I seem to recall a virus nearly killing Ahsoka in TCW.  Also Jedi could be drugged.