American Board of Internal Medicine (ABIM) Certification Practice Exam

What is a common finding regarding the leukocyte count in patients with Rocky Mountain spotted fever?

1. It is always elevated.

2. It can be elevated, normal, or low.

3. It is always normal.

4. It is always low.

The correct answer is: It can be elevated, normal, or low.

In patients with Rocky Mountain spotted fever, the leukocyte count can indeed present in a range of scenarios, making it a notable aspect of the disease's clinical profile. This variability occurs due to the nature of the infection caused by the Rickettsia rickettsii bacteria, which leads to a systemic inflammatory response. Leukocytosis, or an elevated leukocyte count, can often be observed, particularly in the early stages of the illness as the body mobilizes its immune response. However, it is not uncommon to see a normal leukocyte count or even leukopenia (low leukocyte count) in some patients. This inconsistency across different patients and even at various stages of the same patient's disease illustrates the unpredictable nature of the leukocyte response in this condition. Consequently, acknowledging that the leukocyte count can be elevated, normal, or low reflects a more nuanced understanding of the disease pathology and the body's immune response during an active Rocky Mountain spotted fever infection. This complexity emphasizes the importance of considering a variety of clinical findings when diagnosing and managing the disease.