Why is the immune system so fast to respond to allergens, but take days to fight off a legitimate infection?

Question

Why is the immune system so fast to respond to allergens, but take days to fight off a legitimate infection?

In: 5304

Answer 1

I think you are exposed to millions of pollen or dust particles all at once, so the immune reaction is immediately strong. But with diseases, you are only exposed to a handful of microorganisms, so the immune response is minor until the number of microorganisms becomes large.