As Mystery Illness Spreads, New Clues to Its Cause

Officials with the Centers for Disease Control and Prevention said Monday tests revealed traces of a form of microbe known as a coronavirus in the tissue of people infected with the flu-like illness called “severe acute respiratory syndrome,” or SARS.

There are three known varieties of the coronavirus, but the CDC said Monday the culprit in the Asian outbreak appears to be genetically different and probably represents a fourth type.

“There’s very strong evidence to support coronavirus” as the cause, CDC director Dr. Julie Gerberding told reporters Monday. “If [coronavirus] is not the entire cause of SARS, it at least contributes to it.”

But she cautioned that more testing is needed before experts can be certain that this virus causes SARS. No approved treatment exists either for SARS or what could be the illness’ cousin, the common cold.

The researchers collected tissue from four patients who died from SARS and found coronavirus in samples from two of the four. Gerberding said that simply finding the virus does not mean that it causes SARS. But she noted that there is evidence that patients develop an immune system response to the virus.

Besides colds, coronavirus can cause respiratory illnesses that sometimes lead to bronchitis and pneumonia. Other forms can be much more dangerous, causing significant lower respiratory tract illnesses among animals, Dr. Frederick Hayden, clinical virologist for the University of Virginia Health System, told the Associated Press.

The Defense Department is testing the virus against all known antiviral drugs to see if any are effective, Gerberding said. There has been progress with antivirals against other respiratory viruses, particularly influenza, and some of those drugs have been effective in studies against some coronaviruses.

Last week, the World Health Organization thought a possible cause was paramyxovirus — the family of viruses that causes measles and mumps. CDC officials looked for paramyxovirus during their testing, but instead found evidence that a new form of coronavirus was the cause.

SARS is widely believed to have started in southern China late last year and then spread first to Hong Kong, Singapore and Vietnam and later to other countries including the United States, Canada Britain, France, Australia, and Japan. Health authorities say it appears to spread from close contact, primarily through nasal fluids by coughing or sneezing.

In the United States, 39 suspect cases of SARS are under investigation. Most of those suspected cases are believed to have acquired it from recent travel to Asia. The others were health workers or family members who had close contact with those affected, Gerberding said.

The Geneva-based World Health Organization issued a worldwide travel alert March 15 warning people to watch for symptoms after traveling to places where the disease has appeared. The WHO mobilized its network of 11 labs around the world to find the cause and treatment of the disease.

Meanwhile, fears of the disease seemed to spread in Asia: Singapore quarantined more than 700 people who may have been exposed to the disease, threatening them with fines; Hong Kong officials met to draw up health guidelines for everything from restaurants to bus systems in an attempt to slow its spread.