Researchers are moving closer to identifying the cause of a mysterious illness that has now sickened nearly 600 people worldwide, killing 14. Researchers in Hong Kong and Germany have found traces of the viral suspect in several additional patients, and scientists in Singapore said Wednesday that they had also found similar particles in patients there.
The virus is a paramyxovirus, a member of a family that causes mumps, measles and various respiratory diseases. Although health authorities caution that it may still be an innocent bystander in the new disease, its discovery in increasing numbers of patients makes it a stronger candidate as the cause of severe acute respiratory distress syndrome, or SARS.
The new findings are "an encouraging step forward," said Dr. Julie Gerberding, director of the U.S. Centers for Disease Control and Prevention. She said the CDC has not been able to confirm any of the findings because the agency only began receiving blood samples Wednesday.
Gerberding said the CDC has now received reports of 40 U.S. patients with suspicious symptoms and is actively investigating 11 of them -- including two in Los Angeles. The symptoms include high fever, coughing and difficulty breathing. The suspicious cases all involve people who recently traveled to China, Hong Kong or Vietnam, or had close contact with someone who traveled there.
The two Los Angeles cases involve a man who fell ill March 11 shortly after returning from a visit to Vietnam, Hong Kong and China, and his child. The child was hospitalized overnight earlier this week, but has now largely recovered, according to Dr. Jonathan Fielding, director of the County Department of Health Services.
"It's going to take some days to know for sure" if any of these suspected cases are actually SARS victims, Gerberding said.
In another development, Hong Kong officials said that seven SARS victims there all stayed on the same floor of the Metropole Hotel in Hong Kong in mid-February, suggesting that the causative agent, whatever it may be, might be transmitted more easily than scientists had previously believed. The current view is that the agent is transmitted in airborne droplets and that transmission requires close personal contact, perhaps for extended periods.
None of the staff in the hotel has contracted the disease, however, and authorities are trying to determine how much contact the seven had with each other.
The virus was first reported Tuesday by German researchers who found it in nasal swabs of a Singapore physician who fell ill on a flight from New York City to Frankfurt. Dr. H. W. Doerr of the University of Frankfurt said Wednesday that the team had subsequently found it in blood samples from the physician's mother-in-law, who is also hospitalized with the disease. The presence of the virus circulating in blood is a strong indication of an active infection.
Dr. John Tam of the Prince of Wales Hospital in Hong Kong reported Wednesday that his team had identified the virus in three other health-care workers in addition to a case reported Tuesday. And researchers at Singapore General Hospital said they had identified a paramyxovirus as the likely infection agent in a patient there, although they did not release details.
Previous tests had found no evidence of common paramyxoviruses in samples from hospitalized patients, so researchers suspect the disease may be caused by a previously unrecognized member of the family. Several other novel paramyxoviruses have been discovered recently, including two -- the Hendra and Nipah viruses -- that have proved fatal to humans.
Hendra virus killed two people in Australia in 1994 and 1995 after it was transmitted to humans from horses. Nipah virus, transmitted from pigs, killed 105 people in Singapore and Malaysia in 1998 and 1999.