A rchive Date
[ 30-04-2003 ]
Category
[ International Relations ]
sub-Categoy
[ Canada ]
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[http://chealth.canoe.ca/health_news_detail.asp?news_id=6974
Coronavirus testing shows troubling results
Provided by: Canadian Press
Written by: HELEN BRANSWELL
Apr. 30, 2003
TORONTO (CP) - Canadian testing for the coronavirus believed to cause SARS has turned up a puzzling, possibly troubling finding: a significant proportion of people who weren't diagnosed with SARS tested positive for the virus, a leading scientist told an international congress on the disease Wednesday.
As participants at the two-day conference tried to puzzle out some of the mysteries surrounding the disease, the toll it has exacted in Toronto rose again.
Ontario officials announced that two more men had died - a 39-year-old and a 72-year-old - bringing the Canadian death toll to 23.
The 39-year-old man did not have any underlying medical conditions before he contracted SARS at a Toronto hospital last month. He is the youngest person to have died from SARS in Canada, said Dr. Donald Low, one of Canada's leading infectious disease experts and a key member of the SARS containment team.
The older man became infected with SARS while travelling abroad, Low said.
To date, most, though not all, of the people who have died of SARS in Canada had pre-existing diseases and were elderly. Since the beginning of the outbreak here, Ontario has recorded 262 probable and suspect cases of SARS. Most have recuperated and been released from hospital. After Wednesday's deaths, there were 36 probable cases on the active case list.
The national microbiology laboratory in Winnipeg found evidence of the SARS coronavirus in 14 per cent of roughly 550 people who were under investigation for SARS but who never met the case definition, said Dr. Frank Plummer, the lab's scientific director.
Some had exposure to a case or had travelled to affected regions; some did not, Plummer told scientists, public health officials and government authorities from Canada, the United States, Mexico, Britain and Southeast Asia who were attending the Health Canada conference.
While the World Health Organization and the U.S. Centers for Disease Control continue to say definitely that the new coronavirus is the pathogen behind SARS, Plummer remains a voice of skepticism. His researchers are finding evidence of the virus in only about 40 per cent of samples from Canadians who were diagnosed as probable SARS cases and in about 30 per cent of suspect cases, he reported.
But it was this new group, people Plummer called "neithers" - as in neither suspect nor probable - that drew interest Wednesday.
"These 14 per cent . . . we need to understand what the meaning of that is," Plummer said. "They're an interesting group and of concern because those are individuals who don't meet the clinical case definition of SARS.
"That may mean there's a fair bit of mild illness caused by this coronavirus that we're not recognizing. And I think it will mean that it will be much harder to control with quarantine and isolation if the coronavirus is the whole story."
That said, Plummer admitted that at this point there is no evidence these asymptomatic people - if they did have a mild case of SARS - could pass the virus to others who might then become sick with the disease.
"Right now the evidence is, as far as we know, that they're not. There doesn't seem to be any secondary transmission. But our information is still pretty sketchy. So we are actively looking into that question. It is a concern."
Others agreed it was plausible that the virus would cause a broad spectrum of illness, with some people's disease being so mild they may never come to the attention of authorities.
"You'd expect with any disease that there's going to be a spectrum of illness," said Low.
While he acknowledged such a group might be cause for concern, he suggested that if they were infectious, public health officials would have been seeing small, unexplained clusters of patients in the community.
Such has not been the experience in Toronto, Hong Kong or Singapore, Low said, "which suggests that yeah, maybe we are having people that have mild disease, not sick enough to seek medical attention, but they're not transmitting it."
A representative from the CDC, Dr. Stephen Ostroff, admitted test findings at the Atlanta-based organization are also showing puzzling results for the coronavirus. Of 20 probable and 40 suspect cases, evidence of coronavirus was found in only six of the probable cases and none of the suspect ones.
Ostroff, who is deputy director of the CDC's national centre for infectious diseases, suggested a possible explanation.
SARS is extremely difficult to distinguish from a wide variety of pneumonias and there is at present no diagnostic test. Having seen in the Toronto outbreak what havoc one undiagnosed case of SARS can wreak on the health-care system, officials have erred on the side of caution and included people in the SARS caseload who may ultimately be found never to have had the disease.
"By casting such a wide net, you have the potential to include a lot of individuals that ultimately are not going to turn out to have SARS when all is said and done," he said.
Health Canada called the conference to take stock on what has been learned about SARS - a problem all involved in the fight to contain the disease say has been difficult to do while they have been in the trenches.
"We're trying to look at the experiences we've taken for the last six to seven weeks. Then we can say: Do we need to do things differently? And hopefully then, in terms of the rest of the world and the rest of the country, we can demonstrate what works, what doesn't and then see where we need to go on from here," said Dr. Paul Gully, senior director general of the department's population and public health directorate.
 World Fact Book (CIA)]
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