Mononucleosis, the curse of high school and college students, doesn't have to bring social and academic lives to a screeching halt, researchers say. Instead, the disease can be treated to shorten the duration of the illness and reduce the chance of transmission.

In a study presented Sept. 14 at the Interscience Conference on Antimicrobial Agents and Chemotherapy in San Francisco, University of Minnesota researchers found that students who receive an antiviral medication early in the course of the illness become less sick than those offered the standard advice to rest for several weeks.

The results are similar to a previous study by the same researchers on a different antiviral drug. But whether doctors embrace treatment of mononucleosis may depend on how they view the illness.

"When you are in a health service at a university or a big high school, you appreciate how many patients there are and how sick kids can be," said Dr. Henry H. Balfour, the lead author of the papers and a professor of laboratory medicine and pathology. "We have kids miss entire semesters, and their studies suffer."

Commonly known as the kissing disease, mononucleosis is caused by the Epstein-Barr virus. About 140,000 people become ill with mononucleosis each year in the United States, most of them between the ages of 15 and 25. Ninety percent of adults have been exposed to mono, but, for reasons that aren't clear, not everyone becomes sick when infected. People who are infected as children, for example, often have only mild symptoms that go unnoticed. People who are first infected as teenagers or adults become much sicker.

Traditionally, rest is the only recommended treatment; medications are offered simply to ease symptoms such as swollen glands and a sore throat.

Opinions vary about whether the illness is worth treating. After several weeks of extreme fatigue and flu-like symptoms, most patients recover with no lingering effects. But recent research suggests mono is not so innocuous. People who have been infected with Epstein-Barr virus carry a moderately higher risk of developing multiple sclerosis. A few types of cancer -- as well as arthritis, lupus and chronic fatigue syndrome -- have also been linked to Epstein-Barr virus.

"I think there would be a lot of interest in treating mononucleosis if we found something that worked," said Dr. Ben Z. Katz, a pediatrics professor at Northwestern University School of Medicine. In a study published in July in the journal Pediatrics, Katz found that about 10% of adolescents diagnosed with the illness still have symptoms -- mostly severe fatigue -- six to 12 months later.

The study involved 23 university students who had mononucleosis and had been sick for less than two weeks. They were given either an experimental antiviral drug called valomaciclovir or a placebo for three weeks; the students receiving the drug had less of the virus in their mouths and recovered faster than did those who received no treatment. The students taking the antiviral medication reached a 50% improvement in symptoms in 7.6 days compared with 11.1 days for the placebo group.

"The drug gets rid of the virus. That's the first thing you have to show," Balfour said. "The clinical benefit is that the kids got better faster."

Because the load of virus in oral secretions is reduced, treating the infection may also reduce person-to-person transmission, Balfour said.

Valomaciclovir is under development by Epiphany Biosciences of San Francisco, which funded the study. The medication is in its second phase of studies for mononucleosis and shingles, said Christian Hofmann, vice president of business development.

"Both mononucleosis and shingles are sort of underappreciated diseases in terms of how much they affect quality of life," he said.

Balfour said more research is needed on the dosage and how the medication dissolves in the stomach and intestines. He also reported that one student who took the medication developed pancreatitis and was briefly hospitalized. Because pancreatitis is sometimes a complication of mononucleosis, it's unclear what role the drug played, if any, in the condition.

Previous studies suggest that a drug already on the market, valacyclovir (Valtrex), is also effective against mononucleosis. Balfour presented data at the 2005 meeting of the Interscience Conference on Antimicrobial Agents and Chemotherapy -- the annual infectious diseases meeting of the American Society for Microbiology -- that found valacyclovir significantly lessened the severity of the illness for 10 treated students compared with 10 untreated students. The treated students also had significantly less virus in their saliva and throat after two weeks.

In another study published in the journal International Pediatrics in 2003, researchers treated 45 children with mononucleosis using either valacyclovir and a steroid or a placebo. After 20 days, more than three-quarters of the children receiving the medications showed significant improvement while no children receiving placebo drugs had significant improvement. Valacyclovir has been used safety for many years for the treatment of herpes infections.

All of the studies have been small, however, and much larger numbers will be needed to confirm a benefit from antiviral treatment, Balfour said. Further, he added, more attention should be paid to the consequences of mononucleosis infection in order to assess the value of treating people with the infection.

"We think it's worth treating," Balfour said. "But not everyone thinks so."