Infectious mononucleosis, or mono in short form, is a contagious viral illness caused most frequently by the Epstein-Barr virus (EBV). EBV belongs to the herpes virus family and is responsible for most mononucleosis cases. Cytomegalovirus (CMV), another member of the herpes virus family, is responsible for causing about 8 percent of mono cases. Clinically, cases of mono caused by EBV are indistinguishable from those cases caused by CMV.
The incubation period for mononucleosis is about four to six weeks. The characteristic set of symptoms, commonly referred to as the clinical triad, includes:
- Sore throat
- Fever
- Swollen lymph nodes
In addition, physical examination and laboratory analysis may reveal:
- Fatigue
- Malaise
- Strep throat
- Headache
- Body aches
- Rash
- Mild hepatitis
- Enlarged spleen
- Atypical lymphocytosis
- Heterophile antibody
Mono is most common in adolescents and young adults, although anyone of any age can get the infection. EBV infects over 95 percent of the population worldwide. Some people carry the virus but do not develop signs and symptoms of mono.