Which disease could yield a false-positive result if a patient also has Lyme disease?

A false-positive result in serological testing occurs when a test indicates the presence of a disease or condition that is not actually present. In the case of Lyme disease, certain antibodies produced in response to the infection could cross-react with antigens used in tests for other diseases.

Specifically, in syphilis testing, methods such as the RPR (Rapid Plasma Reagin) or VDRL (Venereal Disease Research Laboratory) can yield false-positive results due to the presence of non-specific antibodies that may occur during the course of Lyme disease. These tests are designed to detect reagin antibodies, which can also be present in various conditions, including Lyme disease, leading to a false-positive reaction.

Other diseases listed, such as AIDS, cold agglutinins, and hepatitis C, do not typically cause false-positive results in syphilis testing because they do not involve the same cross-reacting antibodies as those seen with Lyme disease. Understanding the immunological response in Lyme disease helps clarify why it can interfere with the accuracy of certain tests, particularly in the context of syphilis testing.