Which virus is typically associated with asymptomatic infection and >20% reactive lymphocytes?

The Epstein-Barr virus (EBV) is known for its association with infectious mononucleosis, where patients may experience a significant increase in reactive lymphocytes, often exceeding 20% of the total lymphocyte count. A key characteristic of EBV infection is that it often causes asymptomatic infections, particularly in younger populations. Many individuals, especially adolescents and young adults, may contract EBV in a form that does not present noticeable symptoms but still leads to a substantial immune response characterized by the presence of atypical or reactive lymphocytes.

In contrast, other viruses listed may have different clinical implications. For instance, Human Immunodeficiency Virus (HIV) tends to present with more overt symptoms and complications over time, while Cytomegalovirus (CMV) infections can also occur asymptomatically but do not typically feature such a marked increase in reactive lymphocytes as a common hallmark. Herpes Simplex Virus (HSV) often presents with clear symptoms and specific localized lesions, making it less likely to be associated with asymptomatic infection and the lymphocyte patterns described.