American Board of Internal Medicine (ABIM) Certification Practice Exam

What is the recommended test for a patient showing symptoms of Zika virus infection after returning from an endemic area?

1. Bacterial culture

2. Polymerase chain reaction on serum and urine samples

3. X-ray analysis

4. Blood serology

The correct answer is: Polymerase chain reaction on serum and urine samples

The recommended test for a patient showing symptoms of Zika virus infection after returning from an endemic area is polymerase chain reaction (PCR) on serum and urine samples. This method is highly sensitive and specific for the detection of Zika virus RNA during the acute phase of the infection, particularly in the first two weeks after symptom onset. PCR testing is effective because it directly identifies the viral genetic material, which allows for a quicker and more reliable diagnosis compared to other methods. In cases of Zika virus, early detection through PCR can help manage the patient's clinical care as well as inform public health responses, especially in controlling mosquito populations and advising on the risks of transmission. Other testing methods, such as serology, may not be as helpful during the acute phase because IgM antibodies can take time to develop and may cross-react with other flaviviruses, leading to potential false positives. Blood cultures, while beneficial for identifying bacterial infections, are not appropriate for viral diagnosis. Lastly, X-ray analysis does not play a role in diagnosing viral infections and would not provide relevant information in this context. Hence, PCR on serum and urine is the most reliable and recommended approach for suspected Zika virus infections.