SARS death rate doubles to 5.6% since mid-March

Officials wonder if virus is toughening, less-healthy are becoming infected


The death rate from severe acute respiratory syndrome has more than doubled to 5.6 percent since the epidemic was first detected in mid-March, causing deep concern among health officials.

Although the overall death rate from the World Health Organization's statistics has hovered around 4 percent over the past three weeks, it has varied widely among the 26 countries - and Hong Kong - with SARS cases.

When WHO, the lead agency investigating SARS, first reported daily statistics on the disease, the death rate was about 2 percent. It was 2.4 percent March 17 and 1.8 percent March 18. At that time, the number of cases was less than 220.

But as the number of cases has increased - to 3,861 yesterday - the death rate also has steadily risen, leaving health officials worried. Lacking a precise explanation for the rise, health officials have generated a number of theories. In outbreaks of other new infections, the death rate has usually fallen with time.

"It's worrying, and we hope it is not an indication of a continuing trend," said Dr. Klaus Stoehr, scientific director of WHO's SARS investigation.

Although health officials have calculated a death rate from SARS, it is not final, in part because researchers have not developed diagnostic tests to determine who definitely has the disease.

The 5.6 percent death rate for SARS is much higher than that for the 1918-1919 influenza pandemic, which was less than 1 percent, Stoehr said. But the influenza pandemic killed from 20 million to 40 million people in the world because it spread so quickly.

One theory about the rising SARS death rate is that the initial cases involved health care workers who were healthy adults 20 to 45 years old and who had better access to health care than others. Then as the infected health workers unintentionally spread SARS to their families and friends, and they, in turn, spread it to other people, SARS has infected an increasing number of older people with heart disease, diabetes and other underlying chronic ailments.

A second theory is that many of the SARS deaths occurred among patients who became ill weeks ago but who died only recently after long hospital stays.

Another, more debated, theory is that the SARS virus, which is a newly discovered member of the coronavirus family, has become more virulent as it has infected new generations of cases. While some doctors in Asia have advanced this theory, Stoehr said he was doubtful about it because most viruses establish a balance between killing a large percentage of their victims and allowing people to survive so the virus can continue to be transmitted.

"There's a lot of anecdotal information and speculation but no solid statistical studies, so it is far too early to come up with any conclusions," Stoehr said from his office in Geneva.

WHO has sent teams of epidemiologists and other experts to affected countries to help with immediate problems in controlling the epidemic. But, Stoehr said, setting up studies to answer the many questions that have arisen over the death rate and other issues takes time, staff and money.

WHO is short on staff and money to do all the desired studies and "so far we don't have the data collected properly," Stoehr said.

WHO is awaiting the findings from a study conducted by British scientists involving more than 1,000 of Hong Kong's 1,400 reported cases. The findings are expected to provide critical information that could be clues to why most people recover from SARS and a relatively small number die from it.

The death rate varies among countries for a number of reasons. One is that most of the 26 countries with SARS have reported five or fewer cases, numbers too small to be statistically meaningful.

Sixteen of the countries have reported five or fewer cases, and there has been only one death among them. That occurred in the Philippines, which has had only two cases, producing a death rate there of 50 percent.

In Hong Kong, where 94 of the 1,402 SARS cases have been fatal, the death rate is 6.7 percent. Elsewhere in China, which has reported 1,959 cases, including 86 deaths, the fatality rate is 4.4 percent. In Singapore, there have been 178 cases, including 16 deaths, for a 9 percent death rate.

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