There seem to be two variations on allergies.  One can be desensitized, the
other quite the opposite.  The variation where one breaks out in red splotches
sounds like my old citrus allergy, which I desensitized to over the years of
consuming citrus products.  The child responded to bee stings by developing
a resistance.
 
The other allergic reaction gets worse over time.  I am allergic to scallops.
They send me into anephylactic shock, including breathing difficulties,
convulsions, vomiting, etc.  Some people respond to bee stings in this
manner.  In this case, the reaction gets worse, the more one is exposed.
One has to be careful not to confuse one with the other.  Attempts at
desensitization, if it follows the model of my scallop allergy, could be
fatal.
 
Many beekeepers develop a resistance to stings, after a while.
 
Jane B.