If not treated the person can die and infect others as well.
You can die
you explode
It depends on what and how debilitating it is
He would be in a bad predicament.
An untreated infection may spread to the lymphatic system (acute lymphangitis ), the lymph nodes (lymphadenitis ), the bloodstream (bacteremia ), or into deeper tissues.
flea infestation can cause a puppy to develop anemia and die if left untreated
It will burn the lining of the mouth, throat, esophagus and stomach. If left untreated, you will be in agony until you finally die.
millions of people will be left untreated and maybe die and we have an economic collapse.
the bacterial infection can destroy skin, tissue, and bone or spread throughout the body.
Cats and dogs can die it heart worm is left untreated. Call your vet.
Bacterial vaginosis will not cause blood poisoning, even if left untreated.
If you do anything about it, then by definition you aren't leaving it untreated.