Lori
I don't believe that being bit by a rat would induce pernicious anemia. Usually the symptoms of PA show up after years of low B-12 levels, in other words they wouldn't show up right after a rat bite. The body stores 4-5 years worth of B-12, that's why it takes so long for the body to deplete it's supply and for symptoms to start showing up. Usually there is an underlying cause for PA - strict vegetarianism, anorexia, bulimia, stomach surgery, heredity or for some reason a lack of intrinsic factor in the stomach which does not allow the body to absorb B-12 from food.