Washington, April 20 (Reuters): On March 10, before anyone had heard the term SARS, 18 doctors, nurses and medical students in Hong Kong’s Prince of Wales Hospital were out with fevers.
A few telephone calls later, Dr. Joseph Sung’s team at the hospital had the alarming news that at least 50 health care workers were ill. All had Severe Acute Respiratory Syndrome.
In fact, a single 26-year-old man was responsible for infecting every doctor, nurse or medical student who examined him, all the patients around him, and, eventually, people who came in touch with these cases.
In all, he infected 138 people either directly or indirectly. Five died.
A single former airline flight attendant is considered the “index case” for more than 160 infections in Singapore. She, in turn, was infected by a man believed to have infected seven people staying in the same Hong Kong hotel.
A man who caught SARS from the flight attendant was admitted to Singapore General hospital. His multiple ailments — including chronic kidney disease and diabetes — masked symptoms of SARS, and he infected at least 40 doctors, nurses, patients and guests in two wards, government officials say.
Nearly 400 hospital staff, visitors and patients were quarantined, and two departments were sealed.
Doctors coined the term “superspreaders” to define such patients. “This is a term that we have used because it creates a plausible explanation for the pattern of epidemiology that we’re seeing, but it still is really speculation,” Dr. Julie Gerberding, head of the US Centres for Disease Control and Prevention, said last week.
“We don’t know whether the virus is associated with a lot of spread in an individual cluster because of something having to do with the infected person or if it has to do with the type of containment or failure of the containment procedures that are present there.” The idea of super-spreaders emerged with the AIDS epidemic, when a few people were blamed for infecting many others. Doctors are still not sure if such patients carry an especially infectious form of the virus or whether some other factor, such as behavior, was the cause.
While the HIV virus that causes AIDS is spread in blood and semen, the coronavirus that causes SARS is a relative of a common cold virus and can be spread just as easily.
Doctors are now beginning to back off the idea that “superspreaders” represent something special in the Severe Acute Respiratory Syndrome epidemic, which has killed 172 people and infected nearly 3,500 around the world.
“Since infection control measures have been put in place, the number of new cases of SARS arising from a single SARS source case has been significantly reduced,” the World Health Organization said in a statement. It turns out the 26-year-old Hong Kong “superspreader” was given drugs using a jet nebulizer, which pumps a fog of drugs into a patient’s airways and may have created a mist of infected droplets in the air around him.
Infectious disease specialists say they see many patients with coughs and fevers each day. Now they know to wear gloves and a special mask designed to filter out small particles near such patients.
Patients are now isolated, to protect those suffering from other ailments. All five people who died in the initial Hong Kong outbreak were themselves already seriously ill with something else when they were infected with SARS.
Experts believe the SARS virus is passed on in large droplets, but in case it can become airborne in smaller particles, the rooms of suspected SARS patients have negative air pressure, keeping the air inside from leaking out.