American Board of Internal Medicine (ABIM) Certification Practice Exam

Which tick is known to transmit Lyme disease?

1. Amblyomma americanum

2. Ixodes scapularis

3. Dermacentor variabilis

4. Rhipicephalus sanguineus

The correct answer is: Ixodes scapularis

Lyme disease is primarily transmitted by the black-legged tick, also known scientifically as Ixodes scapularis. This tick is responsible for the majority of Lyme disease cases in the northeastern and north-central United States, as well as in parts of Europe and Asia. The life cycle of Ixodes scapularis includes several stages, and the nymphal stage is particularly efficient at transmitting the bacterium Borrelia burgdorferi, the causative agent of Lyme disease, to humans. The other ticks listed do not primarily transmit Lyme disease. For instance, Amblyomma americanum, commonly known as the lone star tick, is associated with other diseases, such as ehrlichiosis and the emergence of alpha-gal syndrome. Dermacentor variabilis, or the American dog tick, is more commonly linked to Rocky Mountain spotted fever and tularemia. Rhipicephalus sanguineus, also known as the brown dog tick, is primarily associated with canine diseases and does not play a significant role in transmitting Lyme disease. Understanding the specific tick species involved in Lyme disease transmission is crucial for effective prevention and control strategies, as well as for educating the public on the risks associated with these ectoparasites.