American Board of Internal Medicine (ABIM) Certification Practice Exam

What is the most sensitive diagnostic method for detecting Babesiosis?

1. Blood smear

2. Serology

3. PCR

4. Ultrasound

The correct answer is: PCR

The most sensitive diagnostic method for detecting Babesiosis is PCR (polymerase chain reaction). This technique amplifies specific DNA sequences of the Babesia parasite, allowing for the detection of very small amounts of the organism in the patient’s blood. PCR is highly sensitive and can identify the presence of the parasite even when conventional methods, like blood smears or serological tests, may fail to do so. Blood smears are commonly utilized for the diagnosis of Babesiosis and can show the presence of the parasite within red blood cells. However, they are less sensitive than PCR because they may not detect low levels of parasitemia. Serology can indicate exposure to Babesia through the detection of antibodies, but it may take time for antibodies to develop and may not be effective in acute cases. Ultrasound is not used for diagnosing Babesiosis, as it is not a method designed to detect parasites in the bloodstream.