WASHINGTON (Map, News) - As many as 65 people came down with an intense illness after attending a convention at Gaylord National Resort, the cornerstone mega-hotel at the new National Harbor resort.

Prince George’s County health officials said they became aware of the disease after 12 people who attended a medical conference at the convention center reported vomiting and diarrhea while waiting for flights at Ronald Reagan National Airport on Tuesday. Others reported similar symptoms after word of the illness was made public.

Test results returned late Friday showed the sickness was the norovirus, a volatile parasite that requires little exposure before making a home in its victim, said Dr. Donald Shell, county health director. According the Centers for Disease Control and Prevention, norovirus can spread through food or water as well as person-to-person contact. The virus makes its presence known typically within about 35 hours but can become evident within 12 hours of exposure and usually runs its course within 60 hours from when the first symptoms appear. It attacks the gastrointestinal system and there is no evidence that it can cause permanent damage. County health officials tracked the sickness back to Gaylord where the medical conference attendees had met in small groups before traveling on buses back to other hotels, Shell said. The problem seems to be limited to people who attended the conference, and none of the other 1,500 to 2,000 people served by Gaylord reported any problems.

A spokesman for Gaylord declined to comment. Several of those who came down with the illness were hospitalized for dehydration, Shell said.

County health officials were dispatched to the hotel to help clean up the mess left behind by sick guests, he said. A powerful bleach solution was used to kill any virus that might have remained.

fklopott@dcexaminer.com