The Centers
for Disease Control and Prevention says that officials now suspect a global
outbreak of a mysterious pneumonia- like illness is caused by a new type
of coronavirus, not paramyxovirus, as had been suggested previously.
"We are reporting
today that our evidence indicates a new coronavirus is the leading hypothesis
for the cause of this infection," CDC Director Dr. Julie Gerberding said
during a news briefing.
Known forms
of the coronavirus cause common colds and upper respiratory tract infections,
but Gerberding said the evidence suggests "this may very well be a new
or emerging coronavirus infection."
The illness
-- called severe acute respiratory syndrome or SARS -- has infected 458
people in 14 countries and caused 17 deaths since it was first detected
in February.
World Health
Organization officials said previously that results in other laboratories
indicated the cause of the illness might be a new virus in a family called
paramyxoviridae, which includes measles and mumps.
Gerberding said
although the CDC was not ruling out the possibility that paramyxo virus
could be the cause of SARS, the agency's evidence "is very strong" supporting
coronavirus.
"We also are
very respectful of other labs that are collaborating in this investigation
and it's very premature to assign a cause or make dogmatic statements about
the etiology," she said.
CDC researchers
have been able to grow a coronavirus from tissue samples from two SARS
patients. Using a technique called polymerase chain reaction or PCR, they
also have detected genetic evidence of the virus in lung and kidney tissue
from one infected person.
In addition,
three people showed evidence of developing an immune response to the virus
after they became ill. Blood samples showed the patients had no antibodies
to the virus when they first became ill, but they developed antibodies
later as the disease progressed.
"We also are
finding evidence of virus on genetic material in lung secretions, in lung
tissue and in many, many other samples," Gerberding said.
"In scientific
terms this is very strong evidence supporting coronavirus as the etiology,"
she said.
The CDC will
continue to run more tests on more specimens from patients to confirm their
hypothesis, she said. "We hope to be able to ascertain whether (coronavirus)
really is related to the onset of disease and, if so, what is the relationship,"
she said.
Dr. Susan McLellan,
an infectious disease specialist at Tulane University Health Sciences Center
in New Orleans, urged officials to be cautious before accepting coronavirus
as the cause.
"It certainly
sounds pretty good but just like with the parmyxo virus, you have to confirm
it in a variety of patients," McLellan told United Press International.
Coronaviruses
occasionally can cause pneumonia, "but not with the severity that seems
to be occurring in this outbreak," she said.
The CDC could
not recommend specific medications to fight SARS, but Gerberding said the
Department of Defense will be working with the agency to test anti-viral
drugs against the potentially new coronavirus.
"There aren't
any anti-virals that are thought to be particularly (effective) against
coronaviruses, although some of the ones we have may be worth testing considering
the severity of this outbreak," McLellan said.
So far, 39 people
in 18 states have contracted SARS in the United States. Of these, 32 appear
to have become infected while traveling in an affected country with the
remaining seven consisting either of healthcare professionals who took
care of these patients or family members who had close contact.
This pattern
emphasizes the importance of quarantining patients who might be infected
in order to limit the spread of the disease, Gerberding said. Healthcare
workers taking care of SARS patients should wear respirators and gloves,
avoid direct contact with bodily fluids and use appropriate hand hygiene
to prevent transmission to other patients, she said.
--
Copyright 2003 by United
Press International.
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