The scientific name for a white blood cell, which is part of the body's immune defense, is a leukocyte. When someone has an overabundance of these cells in his bloodstream, he is said to have leukocytosis, which is often accompanied by fever. Among the cause of leukocytosis with fever are infections, conditions that cause inflammation in the body, and illnesses that damage bodily tissues. Though stress, including that involving fear or pain, and certain medications can also cause leukocytosis, they are less likely to cause an associated fever.
Besides fever, leukocytosis is often marked by fatigue, dizziness, bruising, abnormal bleeding, and tingling sensations in the affected person’s extremities. Sometimes, a person with this condition also experiences difficulty breathing, changes in his vision, and loss of weight. A person with too many white blood cells can have just one, several, or all of these symptoms.
There are many types of infections that cause a person to develop leukocytosis with fever. Often, an excess of white blood cells is the result of infection with bacteria or a virus, but parasitic infections can cause it as well. One example of a condition capable of causing this change is a lung infection called pneumonia, which can develop because of viruses or bacteria. In fact, even some types of fungi can cause pneumonia, and in turn, leukocytosis with fever.
Sometimes, the overreaction of a person’s immune system to an invader that isn’t really dangerous causes this condition. This sometimes occurs in the case of an allergic reaction to something as simple as pollen or mold. The immune system causes allergy symptoms, such as sneezing and itchy eyes, as well as an increase in leukocytes because it believes it must defend the body.
A person might also experience this change in white blood cell count because of a condition or injury that causes inflammation or as a result of some sort of damage the body has sustained. For instance, a person with arthritis experiences inflammation of the joints, which can cause leukocytosis with fever. Likewise, the kind of damage a person suffers because of burns or cancer can cause it as well. Additionally, conditions that affect the bone marrow, including a type of cancer called leukemia, can cause leukocytosis with fever.
Medication used to treat arthritis, cancer, or a range of other conditions may lead to leukocytosis as well. Likewise, both mental and physical stress can cause a temporary upswing in the number of white blood cells a person has in his blood. This probably won’t happen when a person performs day-to-day tasks, even those he might consider challenging. Surgery, however, and prolonged, exhausting exercise are among the possible culprits.