Studies Confirm Likely Cause of SARS
New Coronavirus Never Before Seen in Humans
SARS still spreading, but no U.S. deaths continued...
Gerberding says the hope is that the CDC is over-diagnosing SARS to cast the broadest possible net and prevent further transmission of the disease. Once reliable diagnostic tests become widely available, she says it is likely that many of these suspected cases will be ruled out.
Three diagnostic tests are currently in use at the CDC, but researchers must show that they produce consistent results before they can become available for widespread use.
Gerberding also addressed recent reports that SARS might potentially pose a threat to the international blood supply.
"We have absolutely no evidence that blood has been a source of transmission of SARS," says Gerberding.
But as an additional precaution, the CDC is working with the Red Cross and FDA to develop a way to screen and defer blood donations from recent travelers from affected areas who may be infected with SARS but not yet developed symptoms.
Isolating the Cause of SARS
Two studies released today in TheNew England Journal of Medicine and another released this week by the British medical journal The Lancet describe the efforts researchers at the CDC and other international laboratories took in isolating a coronavirus as the likely cause of SARS.
Investigators say the identification was the result of a combination of classical and modern techniques including tissue-culture isolation to amplify the agent, electron-microscopy to identify the virus, and molecular studies to confirm the identity of the virus and link it to SARS.
These tests showed the virus was not one of the two coronaviruses known to infect humans or those known to cause disease in animals.
"Presumably, this virus originated in animals and mutated or recombined in a fashion that permitted it to infect, cause disease, and pass from person to person," write Larry Anderson, MD, of the CDC and colleagues from the SARS Working Group in TheNew England Journal of Medicine. "Although the known human coronaviruses are associated with a mild disease (the common cold), the ability of coronavirus to cause severe disease in animals raises the possibility that coronavirus could also cause more severe disease in humans."
Members of the international SARS working group have proposed that the previously unknown coronavirus be named after the WHO official who first alerted health officials to a mysterious pneumonia-like outbreak in Hanoi, Vietnam and subsequently died from the disease.
"Because of the death of Dr. Carolo Urbani during the investigation of the initial SARS epidemic, we propose that the virus be named Urbani SARS-associated coronavirus," they write.
Researchers say the unprecedented international collaboration that led to the rapid identification of the likely cause of SARS should serve as a model for future responses to epidemics of infectious disease.