Common causes of a high white blood cell count include infection, drug reaction, immune system disorder and bone marrow disease, according to Mayo Clinic. Severe allergic reactions, smoking, and high levels of physical or emotional stress may also cause a high white blood cell count.
Both bacterial and viral infections can cause a high white blood cell count, notes Mayo Clinic. Tuberculosis and whooping cough are bacterial infections that commonly result in elevated white blood cells. Rheumatoid arthritis is an example of an immune system disorder that results in a high white blood cell count. Reactions to epinephrine and corticosteroid drugs often lead to an increase in white blood cells. Myelofibrosis is an uncommon form of leukemia that disrupts normal production of blood cells and leads to elevated white blood cells.
Four other forms of leukemia lead to elevated white blood cells, acute lymphocytic leukemia, acute myelogenous leukemia, chronic lymphocytic leukemia and chronic myelogenous leukemia, reports Mayo Clinic. Myelogenous leukemia affects a specific variety of white blood cells called myeloid cells. Lymphocytic leukemia affects a variety of white blood cells called lymphocytes. Polycythemia vera is a blood cancer that leads to increased production of red blood cells and sometimes white blood cells as well.