The sneeze felt around the world probably happened on Feb. 21, as guests waited for an elevator in the Metropole Hotel in Hong Kong.
Medical experts believe it came from a 64-year-old Chinese physician who had treated patients on the mainland for the unusual form of pneumonia now termed severe acute respiratory syndrome (SARS).
When the doctor sneezed, a dozen hotel guests caught the SARS virus, and carried it on their travels around the world, starting SARS's journey from its roots in China to threaten a global epidemic.
That travelogue may be the most visible lesson in decades about the reality of seemingly innocent coughing and sneezing.
People cough and sneeze into the open air - and confined spaces like elevators, buses, airplanes, and offices - without realizing the consequences.
Each cough and sneeze is the natural equivalent of pushing the button on an aerosol spray can. If the person harbors disease-causing microbes, coughing and sneezing sprays them into the air, on a fine aerosol mist of saliva and mucus from the mouth and nose.
Other people inhale the droplets and the microbes. The droplets also get sprayed onto their lips and into their eyes. Mucus membranes in the nose, eyes, and mouth are main gateways through which some disease-causing bacteria infect the body.
Common colds, influenza, and SARS are among the diseases transmitted via this “airborne” route. Colds and flu cause misery for millions of people annually, with flu alone killing 26,000 Americans in a typical year. Globally, it claims an average of 500,000 people annually.
Medical textbooks list “unprotected” coughing and sneezing as major culprits in the spread of respiratory diseases. Unprotected means not covering the nose and mouth.
People tolerate coughing and sneezing into the open because the consequences are hidden and remote. When someone with a respiratory disease coughs and sneezes among other people, count on one thing. In a few days, some may get deathly ill.
Laws protect the public from secondhand smoke, which causes an estimated 3,000 lung cancer deaths in nonsmokers annually, according to the U. S. Environmental Protection Agency.
Secondhand viruses, spread through the air by inconsiderate coughers and sneezers, may rival or exceed that toll in flu deaths alone.
Anti-sneeze/cough laws may be unrealistic. But individuals can protect their own health.
Start by stopping the preposterous custom of blessing people who sneeze. The medical facts justify a frown and a quick exit. Politely ask people to cover their coughs and sneezes.
SARS may be new and exotic, but other old-fashioned precautions also may work.
For instance, avoid touching eyes, nose, and mouth with unwashed hands. Infected people may spread SARS and other viruses by touching their nose or mouth, and then touching doorknobs, elevator buttons, keyboards, and other objects.
Anyone later touching the same object - and their eyes, nose, or mouth - can get the virus. Washing the hands often can eliminate the virus, and prevent infection.