本文发表在 rolia.net 枫下论坛Virus can live 24 hours outside host, study finds
By CAROLYN ABRAHAM
MEDICAL REPORTER
Tuesday, April 22, 2003 - Page A1
E-mail this Article
Print this Article
Doctors struggling to contain the SARS outbreak have laboured for more than a month under the notion that this insidious virus can live no more than a few hours outside a human host.
But disturbing new research has discovered otherwise.
Studies by the U.S. Centers for Disease Control and Prevention suggest that, unlike most respiratory viruses medicine knows, the microbe behind SARS can survive up to 24 hours on inanimate objects, turning any surface into a possible point of transmission.
In response, doctors at Toronto's Mount Sinai Hospital spent the weekend swabbing doorknobs, counter tops, railings and the nooks and crannies of nursing stations to determine the prevalence of the SARS virus in the general hospital environment.
The results of tests to be conducted at Winnipeg's National Microbiology Laboratory might help explain how SARS continues to infect hospital staff, both in Canada and Hong Kong, despite their use of protective gear and general infection-control practices.
The effort is part of a larger study to be conducted with other Toronto-area hospitals, Health Canada and a three-member team from the Atlanta-based CDC.
The CDC team is to arrive today to help with investigations related to the city's outbreak of severe acute respiratory syndrome.
"The trouble is we haven't had a chance to stand back and look at all of these issues, with hundreds of other things going on," said Donald Low, Mount Sinai's chief microbiologist, who called the CDC findings about the longevity of the SARS virus "very bothersome news."
"This might possibly explain why we're seeing so much of this in health workers who have been using infection-control practices."
Dr. Low, Mount Sinai infection-control expert Allison McGeer -- who is recovering from her own battle with SARS -- and Andrew Simor, chief microbiologist at Sunnybrook and Women's College Health Sciences Centre, contacted the CDC for further insight as health workers continued to fall ill over the past week.
During a 1½-hour teleconference on Friday night, the doctors learned that the CDC experts had discovered the new coronavirus behind SARS could live for a full day on an inanimate surface.
"We were all very surprised," Dr. Simor said, explaining that respiratory viruses are known to live a maximum of five hours outside a human host -- even when contained in a droplet of a spit.
Bacteria, because of their tougher outer coats, are known to live for months on inanimate surfaces. But viruses, with their soft, fatty outer membranes, are not nearly as hearty. "They're pretty vulnerable to being washed off with alcohol," Dr. Low said.
As a result, Dr. Simor said, health workers may be infecting themselves with casual contacts in their environments. "Health workers are very careful when they are treating patients, or in the immediate area," he said. But transmission may not necessarily be occurring here.
A Mount Sinai anesthetist and an assistant who had been wearing gowns, goggles, masks and gloves, for example, contracted SARS after intubating an infected patient.
Dr. Low speculated that the oversight may have been as innocent as the hospital staff removing their gowns after removing their gloves, but then touching some inanimate object before washing their hands, and then touching it again afterward. Both staff members are recovering.
Similarly, a Mount Sinai nurse who treated SARS patients and then possibly exposed GO train passengers just as she was becoming sick with the disease herself, is not known to have breached any obvious protocol, Dr. Low said.
Dr. Simor said the SARS virus survival time is not likely "the whole story. But it's certainly a piece of the puzzle."
In other instances, he explained, it may in fact be that certain patients are "super-shedders" who have an uncanny ability to infect others with the virus.
For example, more than 15 Sunnybrook staff who were wearing protective gear are under investigation as possible SARS cases after a four-hour-long effort to intubate a SARS patient.
"It was a very difficult intubation, there were all sorts of aerosolizations of secretions," Dr. Simor said. "Someone's mask and goggles slipped in the process."
He also noted that the SARS caseload has grown steadily in recent weeks and health staff have been working "extra hard." But the joint study with the CDC, he said, should shed further light on how many of these health-worker infections can actually be attributed to fatigue and human error.
In the meantime, Dr. Low said, the CDC revelation is forcing health officials to rethink the rules of engagement in the SARS war and craft even tougher containment strategies, fearing health workers will otherwise continue to fall ill -- as they have in hard-hit Hong Kong and Singapore.
"We can't have health-care workers getting sick like this," Dr. Low said. "What are we going to do? Give them danger pay?"更多精彩文章及讨论，请光临枫下论坛 rolia.net
By CAROLYN ABRAHAM
MEDICAL REPORTER
Tuesday, April 22, 2003 - Page A1
E-mail this Article
Print this Article
Doctors struggling to contain the SARS outbreak have laboured for more than a month under the notion that this insidious virus can live no more than a few hours outside a human host.
But disturbing new research has discovered otherwise.
Studies by the U.S. Centers for Disease Control and Prevention suggest that, unlike most respiratory viruses medicine knows, the microbe behind SARS can survive up to 24 hours on inanimate objects, turning any surface into a possible point of transmission.
In response, doctors at Toronto's Mount Sinai Hospital spent the weekend swabbing doorknobs, counter tops, railings and the nooks and crannies of nursing stations to determine the prevalence of the SARS virus in the general hospital environment.
The results of tests to be conducted at Winnipeg's National Microbiology Laboratory might help explain how SARS continues to infect hospital staff, both in Canada and Hong Kong, despite their use of protective gear and general infection-control practices.
The effort is part of a larger study to be conducted with other Toronto-area hospitals, Health Canada and a three-member team from the Atlanta-based CDC.
The CDC team is to arrive today to help with investigations related to the city's outbreak of severe acute respiratory syndrome.
"The trouble is we haven't had a chance to stand back and look at all of these issues, with hundreds of other things going on," said Donald Low, Mount Sinai's chief microbiologist, who called the CDC findings about the longevity of the SARS virus "very bothersome news."
"This might possibly explain why we're seeing so much of this in health workers who have been using infection-control practices."
Dr. Low, Mount Sinai infection-control expert Allison McGeer -- who is recovering from her own battle with SARS -- and Andrew Simor, chief microbiologist at Sunnybrook and Women's College Health Sciences Centre, contacted the CDC for further insight as health workers continued to fall ill over the past week.
During a 1½-hour teleconference on Friday night, the doctors learned that the CDC experts had discovered the new coronavirus behind SARS could live for a full day on an inanimate surface.
"We were all very surprised," Dr. Simor said, explaining that respiratory viruses are known to live a maximum of five hours outside a human host -- even when contained in a droplet of a spit.
Bacteria, because of their tougher outer coats, are known to live for months on inanimate surfaces. But viruses, with their soft, fatty outer membranes, are not nearly as hearty. "They're pretty vulnerable to being washed off with alcohol," Dr. Low said.
As a result, Dr. Simor said, health workers may be infecting themselves with casual contacts in their environments. "Health workers are very careful when they are treating patients, or in the immediate area," he said. But transmission may not necessarily be occurring here.
A Mount Sinai anesthetist and an assistant who had been wearing gowns, goggles, masks and gloves, for example, contracted SARS after intubating an infected patient.
Dr. Low speculated that the oversight may have been as innocent as the hospital staff removing their gowns after removing their gloves, but then touching some inanimate object before washing their hands, and then touching it again afterward. Both staff members are recovering.
Similarly, a Mount Sinai nurse who treated SARS patients and then possibly exposed GO train passengers just as she was becoming sick with the disease herself, is not known to have breached any obvious protocol, Dr. Low said.
Dr. Simor said the SARS virus survival time is not likely "the whole story. But it's certainly a piece of the puzzle."
In other instances, he explained, it may in fact be that certain patients are "super-shedders" who have an uncanny ability to infect others with the virus.
For example, more than 15 Sunnybrook staff who were wearing protective gear are under investigation as possible SARS cases after a four-hour-long effort to intubate a SARS patient.
"It was a very difficult intubation, there were all sorts of aerosolizations of secretions," Dr. Simor said. "Someone's mask and goggles slipped in the process."
He also noted that the SARS caseload has grown steadily in recent weeks and health staff have been working "extra hard." But the joint study with the CDC, he said, should shed further light on how many of these health-worker infections can actually be attributed to fatigue and human error.
In the meantime, Dr. Low said, the CDC revelation is forcing health officials to rethink the rules of engagement in the SARS war and craft even tougher containment strategies, fearing health workers will otherwise continue to fall ill -- as they have in hard-hit Hong Kong and Singapore.
"We can't have health-care workers getting sick like this," Dr. Low said. "What are we going to do? Give them danger pay?"更多精彩文章及讨论，请光临枫下论坛 rolia.net