Pathfinder disease help?

[MonkeySage]

Urn of Decay(cursed item):
The ashes contained in the urn carry a deadly supernatural disease.
Disease: Ash Putrefaction
Type: Inhaled, contact
Save: Fort DC 16
Onset: 1d4 days
Frequency: 1/Day
Effect: 1d3 Con, 1d3 Str
Cure: 2 consecutive saves
For every day that passes, the body of the infected slowly turns to ash(first manifesting as a dry, itchy rash). Breathing in or touching the ash spreads the infection to other people. Upon death, the body of the infected will crumble into a pile of diseased ashes.

I'm wondering if this is too powerful, what I might do to keep it threatening, while still being something that a player could handle.
I intend to use this for a questline: an npc from a nearby town, one afflicted with the disease, comes into the village my player is staying at. He tells her and the other villagers to stay away from him, before the disease kills him.

The disease has been spreading through said npc's hometown like a plague, unchecked because there are no clerics. My player, currently level 1, is solo, save for an equal level paladin escort(an npc i allow him to control during combat scenarios).

Also, any suggested backstories for the urn? ^_^