Epstein-Barr virus (EBV), the virus that causes mononucleosis - also known as mono or the kissing disease -persists at high levels in the saliva for as long as six months after initial infection, French researchers report. This means that people with mono remain highly infectious during the recovery period, they warn.

For 6 months after infection, researchers measured levels of EBV DNA in the saliva and blood of 20 patients with mono and 10 healthy EBV carriers - the control patients. Dr. Patrice Morand of Centre Hospitalier Universitaire Michallon in Grenoble and colleagues report their findings in the March 15 issue of The Journal of Infectious Diseases.

They discovered that high levels of EBV persisted in the saliva of mono patients during the entire 6-month follow-up period. In contrast, there was a global decrease in EBV levels in the blood.

All of the mono patients had EBV DNA detected in saliva at every point during the follow-up period, and the level of virus was significantly higher compared to levels seen in the healthy EBV carriers.

These findings suggest that patients with mono remain “highly infectious” long after the initial infection, the authors warn.

SOURCE: Journal of Infectious Disease March 15, 2005.