You get the option to use the cure on the boy or keep it for yourself. If you use it on the boy you keep a permanent -10 hp perk from the disease.
Can you avoid contracting the disease if you never get hit by any of the infected molerats by sneaking around or using followers for combat?
You will contract the disease if:
- You get hit by a mole rat
- Your companion gets hit by a mole rat
- The protectron you can activate via terminal gets hit by a mole rat
Long story short, don’t use a companion (or have them stay by the entrance), don’t activate the protectron and Don’t Get Hit. I was able to get through without catching the disease by abusing VATS and quick saves.
Note that the mole rats can be hit by grenades even while underground. If you get ambushed and have to reload, toss a Molotov Cocktail at the ground where the Mole Rat would appear and roast it early.
Also note that burrowed mole rats Will trigger mines. I tried to use mines on top of where they would spawn and blew myself up.