Build Concept: Inocumancer

[Warchon]

Had an idea about a good-aligned Cancer Mage and curious what options exist that might make it viable.
The general concept would be going around intentionally infecting entire villages/cities/nations with comparatively harmless diseases in order to protect them from related, deadlier diseases, much the same as using Cowpox to inoculate people against Smallpox.
Obviously this would require at least two house rules: That such inoculation methods work in D&D, and that a non-evil Cancer Mage is allowed. I am hoping to make this viable without any additional houseruling.
The big hurdle that remains is inventing "lesser" versions of diseases. Is there any way by RAW to create a new one, or to potentially draw links between diseases that reasonably suggest a relationship?

General build advice is also welcome. Leaning on the Cancer Mage class features to spread his chosen diseases is fine (I think he'd make a good tavern brawler with the right chassis, infecting healthy fighters on the sly) but spellcaster ideas are also welcome.

I think it should be a requirement that all levels include Heal as a class skill, and any spare feats should be directed toward a truly prodigious Heal check, to justify that he understands that inoculation works this way, but if inapprpriate classes are attractive a Glimmerskin Halfling as the race would cover that base.

What say you, Giants of the Playground? Viable character idea, or waste of time?

[Ruethgar]

Well... my first thought was Spell Side Effects to reduce damage from Contagion, but none of the side effects are so powerful as to alter ability damage. However considering Rod of Wonder is an option, you could probably make the case for taking off some damage in accordance with the rod’s power level.

Going along with that, granting a bonus feat for a custom Contagion Spelltouched Feat for disease resistance if they survive x days wouldn’t be that out of place I wouldn’t think.

Also, if you don’t want to houserule the Cancer Mage, Ritually Associating yourself with Evil can let you count as Evil without making you evil.

[Troacctid]

What you want is an Opposite Effect (http://www.d20srd.org/srd/magicItems/cursedItems.htm#oppositeEffectorTarget) cursed magic item. A cursed wand that casts contagion, except instead of afflicting the target with a disease, it inoculates them against it.

[The Viscount]

Have you considered using Nosomatic Chirurgeon in place of cancer mage? It has some of the similar themes, but you might find the fluff easier to wrangle.