What is the primary cause of mononucleosis?

Mononucleosis, commonly known as "mono," is primarily caused by the Epstein-Barr virus (EBV), which is a member of the herpesvirus family. This virus is highly prevalent and is often transmitted through saliva, which is why it is sometimes referred to as the "kissing disease."

In the context of mono, the Epstein-Barr virus infects B cells and can lead to a significant immune response, resulting in symptoms such as fever, sore throat, swollen lymph nodes, and fatigue. Recognizing the virus as the primary cause is crucial for understanding both the transmission and the symptomatic management of the condition.

Other options mentioned, such as bacterial infections or streptococcal infections, do not cause mononucleosis. Antibiotics are ineffective for viral infections, including mono, which further emphasizes the significance of identifying the Epstein-Barr virus as the correct answer. Understanding the viral nature of mononucleosis helps guide appropriate clinical management and patient education.