Common Cold Virus Suspected in SARS
CDC Says New Form of Virus May Cause Mystery Pneumonia
March 24, 2003 -- A new form of the virus that causes the common cold may be behind the rapidly emerging outbreak of a mysterious pneumonia illness known as SARS (severe acute respiratory syndrome), according to the CDC. The number of people thought to have SARS has now grown to more than 450 worldwide, including 39 cases under investigation in the U.S., and international laboratories are working at "breakneck speed" to confirm the cause of the deadly illness.
At a briefing today, CDC director Julie Gerberding, MD, presented strong evidence that a new strain of a virus most frequently associated with upper respiratory infections and the common cold in humans called the coronavirus might be likely cause of severe acute respiratory syndrome.
"We are reporting that our evidence indicates that the coronavirus is the leading hypothesis on the cause of this infection," says Gerberding.
Gerberding says laboratory tests performed at the CDC on tissue and blood samples from SARS patients suggest that a new, unknown form of the highly contagious coronavirus is, if not the primary cause of the illness, then at least a major contributor.
The CDC is part of a network of 11 leading international laboratories formed by the World Health Organization that is sharing information to determine a cause and develop treatments for severe acute respiratory syndrome. Previous findings from laboratories in Germany and Hong Kong reported last week implicated a new strain of a virus from the Paramyxovirus family as a possible cause of the illness.
Gerberding says it's still too early to assign a definite cause of SARS, but from a scientific standpoint, this new evidence on the common cold coronavirus is very strong. CDC researchers were able not only to grow the virus in the laboratory based on cultures from two SARS patients, but they also found evidence of the previously unknown strain of coronavirus in tissue samples from affected patients.
Further support for their hypothesis came from blood samples from several SARS patients taken at early and later stages of their illness. Tests found that these patients developed had antibodies to the common cold virus in the later stages that were not initially present (a process known as seroconversion), which suggests that the virus was a likely cause of the illness.
"Everyone is keeping open mind," says Gerberding. "The challenge is that it's a nonspecific illness, and we're dealing with families of viruses that are ubiquitous. And finding them is not same as finding a cause of the disease."
Even so, U.S. secretary of Health and Human Services Tommy Thompson says this finding from the CDC is encouraging news.
"These and other excellent scientists all over the world have been working around the clock for days and their hard work is paying off. They continue to look at other possible causes of SARS, but this is a key finding in our efforts to identify the cause of this global outbreak," says Thompson, in a news release.