London NotesVirus alert.

Posted Thursday, Jan. 24, 2002, at 3:09 PM ET

Winter vomiting sickness, a viral infection first detected in Scotland, has now spread to Sussex, Hertfordshire, Cornwall, Wales, and Northern Ireland. It's arrival in London is believed to be imminent. The symptoms are very discomforting, and include, nausea, diarrhoea, and what has been described as "projectile vomit". As the Public Health Laboratory Service (PHLS), an organisation that monitors the spread of infectious disease in Britain, helpfully explains, the bug—also known as Norwalk virus (after the Ohio town where it was first identified)—is fantastically virulent. "It is caused by an organism called SRSV [small round structured virus]. … This is the most common cause of gut infection in this country. Estimates suggest that there are about 600,000 to one million cases of this disease in England every year." The virus is therefore much more common than salmonella, and much more prevalent in Britain than it is in the United States. The federal government's Centers for Disease Control in Atlanta estimates that only 181,000 Americans contract the virus each year.

Like salmonella, the Norwalk virus thrives off bad practices in large kitchens that cater for hundreds of people—those found on cruise ships, say, or at hospitals, military bases, and big restaurants. Passengers, patients, military personnel, or guests are infected after contact with contaminated food. And these individuals then unwittingly transmit the virus to other people before the symptoms have manifested themselves. (To read the US Army's thorough report on an outbreak of Norwalk virus at Fort Bliss, Texas, in 1998, and the actions taken by doctors to limit the spread of the disease click here.) Three years ago, at a college football game between Florida State and Duke University, a player who didn't realise he had Norwalk virus infected 64 others (teammates as well as members of the opposition).. Or rather, he and the ball did, since many of the players who went down with the bug hadn't come close to him.

In what appears to be an attempt to allay public fears, the PHLS says on its Web site: "Although there are clearly a substantial number of cases of this disease around at the moment, levels do not appear to be out of proportion to those seen in some previous winters." If outbreaks of Norwalk virus in Britain really are as frequent as the PHLS suggests, why is the current outbreak being treated by the press as if it were a new plague?