What causes a high wbc count?

Many things can cause a high WBC count. One of which is infection. WBCs fight foreign bodies in our system that's why if there are viruses, they would increase in count. It's part of the body's defense system. Another possible reason is if there are abnormalities in the blood producing organs of the body. For instance, with Leukemia, there is an abnormally high production of WBC.