Mole rat disease is a potentially permanent effect the player character obtains if bitten by an infected mole rat in Vault 81 during the quest Hole in the Wall. The effect is -10 Max HP. So where health is concerned, the disease permanently lowers the Sole Survivor's Level by 1. During the quest, the Sole Survivor will obtain the only dose of the cure available. If the player character has contracted the disease then there is a choice to either save the life of Austin Engill, a young boy who was bitten by an infected mole rat himself, or use the cure on themselves. If the Sole Survivor cures Austin of mole rat disease, they will gain the favor of the vault as well as a room to stay in and access to all of the publicly-placed items in the vault, even those in the Depot.
For tips on how to prevent contracting the disease, see the quest page.
Notes
On PC, the condition can be removed by spawning an additional cure via console command player.additem 00055f10, by removing the perk that causes the effect via player.removeperk 0023aec1, or by removing all current buffs and debuffs using player.dispelallspells.
Bugs
It is possible to contract the virus without being bitten by a mole rat. This can be caused by a companion getting attacked.[verified]
If the dormant protectron is activated and bitten, the Sole Survivor will contract the disease.[verified]