rabbit hair loosing

my brother has a rabbit ..he  about 6 months old and . we recently noticed that on his ear there a patch of hair missing the size of a dime ..and im scared becuase  did jst recently happend and we fed him some human food but im scared he has a disease or is sick...

[Aleda M Cheng, D.V.M., C.V.A]

Your brother's rabbit should be tested for ring worm, and mites (ear and skin mites) by a veterinarian.  

I don't know what your brother fed your rabbit but wild rabbits have existed for thousands of years on vegetarian people food (all kinds of vegetable produce,  and grains), and non-people food (grasses)  for thousands of years.  If your brother fed something non-vegetarian, that could be a problem, but the problem would be located in his rabbits digestive system and not on his skin.