What is a viral infection that causes fever, sore throat, and swollen lymph glands?

Mononucleosis, often referred to as "mono," is a viral infection primarily caused by the Epstein-Barr virus (EBV). It is characterized by a range of symptoms including fever, sore throat, and swollen lymph glands, particularly in the neck. This distinctive combination of symptoms is key in differentiating mononucleosis from other illnesses.

The fever typically accompanies the immune response to the viral infection, while the sore throat may be due to inflammation of the throat and tonsils as the virus replicates in the mucosal lining. Swollen lymph glands are indicative of the body's immune response, as lymph nodes become active in fighting the virus, leading to noticeable swelling.

In contrast, other options present different illnesses or symptoms. The flu, while it does include fever and sore throat, often features more widespread systemic symptoms such as body aches and cough. Strep throat is a bacterial infection and is characterized by a more severe sore throat and sometimes fever but does not typically cause lymphadenopathy to the same extent as mono. Respiratory infections can include a wide range of conditions, usually focused on the upper respiratory tract and may not manifest the specific triad of symptoms found in mononucleosis.