- A chain of events that began in a microbiology laboratory
in a Vancouver hospital may have helped avert a global pandemic when it
was discovered last month that a potentially deadly flu strain had been
shipped to 4,000 labs worldwide.
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- The alert has led to laboratories around the world rapidly
destroying stocks of deadly H2N2 flu strain, which killed four million
people during a flu pandemic in 1957.
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- But the problem only came to light when the Vancouver
laboratory, which has not been identified, sent a patient specimen to the
National Microbiology Laboratory in Winnipeg.
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- The Winnipeg lab did extensive tests and relayed the
results to the Vancouver facility, which alerted health authorities in
this country and in the U.S. that a deadly strain had been accidentally
shipped to about 4,000 laboratories in 18 countries for practise-only purposes.
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- Ironically, however, it was a mistake made in the Vancouver
lab that eventually led to the discovery.
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- Dr. Perry Kendall, B.C.'s top public health official,
said the chain of events originated in March when the Vancouver hospital
sent a sample from a female patient to the national lab for further testing
to determine what subtype of influenza A she had. It turned out the sample
had been cross-contaminated with H2N2.
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- The sample took three weeks to culture and subtype; results
finally came back on the Easter weekend.
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- Thousands of other labs around the world were also unwittingly
in possession of the H2N2 virus because none had bothered to do the kind
of detailed subtyping that was done in this case.
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- Kendall said the sample was sent for further testing
to Winnipeg because "influenza didn't fit with the patient's clinical
symptoms.
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- "There was no history of her getting anything that
looked like influenza."
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- He said when the national lab revealed the results "we
were really concerned that we had discovered a new strain of influenza
in our population, but then we realized this patient had not travelled,
had no contacts with any potential sources of H2N2.
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- "So upon further discussion, we decided that her
sample was probably contaminated. Then the detective work figured out that
on the same day that her specimen had been prepared for shipping to the
lab in Winnipeg, the lab had also been conducting proficiency testing,"
said Kendall, referring to the tests lab workers conduct to know how to
identify and characterize viral strains.
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- Kendall said the lab is conducting a review to find out
precisely how the cross-contamination occurred.
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- "It's a problem the lab is addressing. It's always
a problem which laboratories can have, because it takes just minute traces
for this to happen.
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- "In a perfect world, cross-contamination would not
occur and it is indeed very rare," Dr. Danuta Skowronski, physician-epidemiologist
at the B.C. Centre for Disease Control, added. "But obviously, humans
are fallible. Those who work in laboratories are taught to assume that
every agent is potentially infectious, whether they know what it is or
not," she said.
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- Kendall said he was refusing to disclose the identity
of the hospital lab "because there is nothing to be gained, from a
public health [point of view by] disclosing it."
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- Skowronski said health officials act on a "need
to know basis and if there is no threat to public health, there is no need
to disclose" the hospital identity.
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- B.C. public health officials said Wednesday it is not
believed any laboratory workers or other citizens in the province -- or
indeed anywhere in the world -- have contracted the H2N2 influenza strain,
which was contained in vials shipped to labs from the United States. The
vials containing live virus were produced by a Cincinnati-based test-kit
maker and shipped by the College of American Pathologists in February so
that lab workers could gain proficiency at typing viral strains for accreditation
purposes.
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- The H2N2 strain hasn't circulated in the world since
1968, so anyone born after that time would have no immunity to it, raising
the spectre that if people suddenly did become exposed to it, a pandemic
could result. H2N2 is considered one of five candidates for an influenza
pandemic.
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- Dr. Perry Kendall, B.C.'s top public health official,
said when the vials were shipped, they were improperly labelled as A/Shanghai,
related to the influenza strain that has been circulating in North America
this past winter. Kendall said it was "neither sensible nor wise"
to send the H2N2 subtype and it was also "unacceptable to mislabel
the vials."
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- The U.S. government is investigating. The WHO has alerted
labs which received the virus to destroy it.
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- © The Vancouver Sun 2005
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- http://www.canada.com/vancouver/
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