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Is hand hygiene the key to the SARS puzzle?
Surface contamination plays role in spread
Surface contamination may be an important method of transmission of the virus that causes severe acute respiratory syndrome (SARS), according to investigations by the Centers for Disease Control and Prevention in Atlanta.
When investigators swabbed surfaces at two hospitals in Toronto, they found virus particles on the bed table and bathroom door handle in one patient’s room, on a TV remote control in another patient’s room, and on the door handle on the nurse’s station medication refrigerator, reports Matthew Arduino, MS, DrPH, chief of the CDC’s Applied and Environmental Microbiology Section.
However, those positive tests don’t necessarily mean there was "any infectious presence," he notes.
The pattern of SARS transmission has puzzled investigators. For example, a physician staying at Hong Kong’s Hotel Metropole on the ninth floor is believed to be the index case that infected hotel guests on other floors. However, his wife, who was sharing the room with him, never became ill. Neither did any hotel workers.
In Toronto, a 96-year-old patient became ill with SARS in early April, apparently from a nurse who worked on the same floor and who did not know she had SARS. She was not involved in the patient’s care. He was transferred to the fourth floor orthopedic ward, where he infected almost a dozen nurses, according to news reports. Three patients on the seventh-floor psychiatric ward also became ill with SARS symptoms.1
"We have more questions than we have answers now," says Arduino. But he says fomite transmission, or surface contamination, is likely to be a major component, which makes hand hygiene an important control measure.
Industrial hygienists from the National Institute of Occupational Safety and Health and the Canadian worker safety agency are investigating the most recent outbreaks. That approach is critical to preventing future transmission, says Gabor Lantos, MD, PEng, MBA, president of Occupational Health Management Services in Toronto.
"There are all these variables that need to be looked at in a systematic fashion," says Lantos. "This needs an industrial hygiene/occupational safety approach."
For example, hospitals need to provide training to health care workers on the proper removal of personal protective equipment, he says. "The respirator should be the last item coming off. The gowns are contaminated, the gloves are contaminated. If you take off your mask first, you’re whipping off everything and breathing it in," he says.
The proper order in which to remove personal protective equipment, says Lantos, is as follows:
— Remove head covering, gowns, and booties.
— Take off gloves.
— Remove mask and wash your hands.
"You’ve got to come up with a program that’s workable," he says.
Although hospital transmission has been a major aspect of the SARS epidemic, it has afflicted few workers among housekeeping staff.
"There were at least three health care workers in Vietnam whose only job was to clean a SARS patients’ room," says Linda Chiarello, RN, MS, of the CDC’s Division of Healthcare Quality Promotion. The patient was there for part of the time the cleaning took place, she says.
In Canada, one patient care assistant (PCA) contracted SARS. In addition to cleaning rooms, PCAs deliver medication to patients and assist with transport. In Taiwan, a hospital laundry worker and a desk clerk developed SARS.
In the United States, there have been no hospital outbreaks and only one case of a health care worker with probable SARS. Of 74 probable SARS cases, only eight have been confirmed through laboratory tests.
High degree of containment required
"I think the most important thing is for us to keep being vigilant," says Dan Jernigan, MD, a CDC medical epidemiologist involved in the SARS investigation.
SARS cases have declined, and the World Health Organization has removed advisories cautioning against non-essential travel for all affected areas. In late June, the WHO reported 8,461 cases of SARS worldwide, with 804 deaths.
The CDC will remain alert for signs of new transmission, CDC director Julie L. Gerberding said in a press briefing.
"It is clear that the common theme of most of the outbreak situations we have encountered has been a spread from affected patients to the health care workers and then into the community," she said. "And we have recognized now twice in Canada that a very high degree of containment is required to protect people."
1. Donovan K, Talaga T. How experts untangled threads of second outbreak. Toronto Star, June 14, 2003. www.thestar.com.