What symptom is commonly associated with infectious mononucleosis in the context of serological testing?

Infectious mononucleosis, often caused by the Epstein-Barr virus (EBV), is characterized by a range of symptoms that can be detected through serological testing. Peripheral blood lymphocytosis is a hallmark sign of this condition, reflecting an increase in the number of lymphocytes in the blood. These lymphocytes are predominantly atypical T-cells that respond to the viral infection.

The presence of lymphocytosis is crucial in the diagnosis of infectious mononucleosis. While other symptoms such as elevated liver enzymes and generalized lymphadenopathy can also be present, lymphocytosis specifically alerts clinicians to the immune response being activated in reaction to the EBV infection. Therefore, detecting this increase in lymphocyte count during serological testing is significant for confirming the diagnosis of infectious mononucleosis.

Additionally, the presence of antibodies to Treponema pallidum is unrelated to mononucleosis, as this antibody would indicate syphilis rather than a viral infection. Thus, the detection of peripheral blood lymphocytosis stands out as the most relevant symptom in the context of serological testing for infectious mononucleosis.