Mononucleosis, more commonly known as mono–or the kissing disease, is fairly common to teenagers. Most teenagers recover in a couple of weeks, but for some the symptoms persist for years in what is referred to as post-infective fatigue. It is thought that post-infective fatigue is linked to the Epstein Barr virus (EBV) also known as chronic fatigue.

Researchers selected 10 subjects.  One group of 5 subjects had post-infective fatigue that lasted for at least 6 months, while the remaining 5 subjects had recovered from their bout with mono. Blood samples where taken at various times. What the researchers were looking for was a genetic difference between those with a long-lasting form of the disease and those who recovered from it within a normal time frame.

Scientists found that there were genetic changes in the group with long-term symptoms. The reason that some people’s immune systems were better at fighting the disease than those where the disease persisted long-term is not understood, but the discovery of the genetic change shines light on where research needs to continue.