Infectious mononucleosis, commonly referred to as mono, is an infection caused by the very common Epstein-Barr Virus (EBV). EBV is transmitted by bodily secretions, primarily saliva, which is why mono is often called "the kissing disease." The vast majority of people in developed countries are exposed to the virus at a young age and often experience very subtle, if any, clinical symptoms. Sometimes, when someone slightly older is exposed to the virus for the first time, he/she may develop signs of an acute infection; this classically occurs in teenagers and young adults.
Typically, symptoms do not show up until 1-2 months after transmission of the virus. The most common symptom is prolonged and significant fatigue. Other common symptoms include sore throat
, low-grade fevers, swollen lymph nodes, muscle aches and nausea.
The combination of your girlfriend having mono, the symptoms you are experiencing, and the time-course of symptoms all suggest mono as a possible cause. You should see your primary care physician
, who can perform a physical exam and blood tests to help confirm the diagnosis. Importantly, if mono is diagnosed, you should refrain from significant physical activity for several weeks, as there is a increased risk of damage to the spleen late in the course of mono.