Can S.A.R.S. Spread Through Indoor Air?

 
April 15, 2003 -- Atlanta.
For the first time last week, the Centers for Disease Control and Prevention (C.D.C.) has acknowledged the possibility that S.A.R.S. may be able to spread through the air or from touching objects that have become contaminated. Health officials point out, however, that there are no confirmed cases at this time of S.A.R.S. being transmitted in these ways.


This concern was prompted by a number of people who have become sick in a Hong Kong apartment block. According to David L. Heymann, M.D., executive director of the World Health Organization's (W.H.O.) communicable disease program, more than 260 S.A.R.S. cases have been linked to the Amoy Gardens estate of high-rise apartment buildings.
"The vast majority of Amoy Gardens cases have been traced to vertically linked apartments in a single building, Block E. This pattern of transmission indicates that the disease has moved out of the health care setting and is now occurring within the community as secondary cases," he said during his April 11, 2003 briefing.
He also noted that epidemiologists investigating the Amoy Gardens outbreak are considering that some form of environmental contamination, perhaps linked to a sewage or ventilation system, is the source of the large number of cases. Although transmission through the fecal-oral route is being considered as one possibility, there is no evidence at this time of airborne transmission. Also the virus that is suspected of causing S.A.R.S. has not been detected in animals, including cockroaches and rodents. Residents of this apartment block haven been quarantined in their homes to help prevent further spread of the disease.
The C.D.C. also has expressed concerned about reports of suspected S.A.R.S. cases that may be related to community transmission in Florida. In her April 10, 2003 telebriefing to the news media, C.D.C. Director Julie Gerberding, MD, said, "One situation, in particular, involved a person who traveled to Asia and developed an illness consistent with S.A.R.S.. In the very early phases of that illness, the individual did go to work, and during the active monitoring of [the individual's] contacts, that the Florida health department is conducting, an individual in the workplace who has respiratory illness was identified. So that worker is now on the list of suspected S.A.R.S. patients but it's far too early to indicate whether any of these individuals actually has S.A.R.S. or [that S.A.R.S. has] spread beyond that point." There also is a child in Florida with a suspected case of S.A.R.S. who attended school.
With respect to possible transmission of S.A.R.S. at airports, Dr. Gerberding commented, "If you are a passenger traveling from an unaffected part of the world, but you go through an airport in a country like, say, Hong Kong, where disease is being transmitted, it's possible that you would come in contact with someone who is infectious. And so we are considering that as a potential exposure as we learn more about how this disease is being spread."
As a precaution, the C.D.C. has posted guidance on its website to ensure that there are appropriate steps in place to manage possible exposures should an individual with S.A.R.S. inadvertently go to the school or to work.
Severe Acute Respiratory Syndrome (S.A.R.S.) is an emerging disease that most likely spreads from close personal contact during which someone with the illness coughs droplets into the air and someone else breathes them in. This usually occurs with family members or health care providers who are treating people with S.A.R.S..
The illness is described as an atypical pneumonia that is likely caused by a previously unrecognized coronavirus. It usually begins with a fever greater than 100.4 F, which is sometimes associated with chills or other symptoms, including headache, general feeling of discomfort and body aches. Some people also experience mild respiratory symptoms at the outset. After two to seven days, S.A.R.S. patients may develop a dry, nonproductive cough that might be accompanied by or progress to the point where insufficient oxygen is getting to the blood. In 10% to 20% of cases, patients will require mechanical ventilation. The incubation period for S.A.R.S. is typically two to seven days; however, isolated reports have suggested an incubation period as long as 10 days.
Information to date suggests that people are most likely to be infectious when they have symptoms, such as fever or cough. However, it is not known how long before or after their symptoms begin that patients with S.A.R.S. might be able to transmit the disease to others.