Faculty Bibliography

The WHO has said the SARS virus, which is a newly discovered member of the coronavirus family, is the cause of SARS. But the agency and other scientists agree that more work needs to be done to be certain. Scientists know that other coronaviruses have a high rate of mutation and so they say that it is far too soon to know whether the SARS virus will change to cause milder, or even more severe, illness, or become a seasonal disease, like influenza and other corona viruses. CDC researchers have developed a test like the Elisa, which is used to screen for the AIDS virus and other infectious agents. The SARS test is expected to have limited use because it cannot detect antibodies until three weeks after the onset of illness. A positive result would strongly indicate that an individual has been infected with the SARS virus, but a negative test will not necessarily rule out such infection, [Julie L. Gerberding] said

C.D.C. researchers have developed a test like the Elisa, which is used to screen for the AIDS virus and other infectious agents. The SARS test is expected to have limited use because it cannot detect antibodies until three weeks after the onset of illness. A positive result would, however, strongly indicate that someone had been infected with the SARS virus, while a negative test would not necessarily rule out such infection, Dr. [Julie L. Gerberding] said. The World Health Organization has said the SARS virus, which is a newly discovered member of the coronavirus family, is the cause of SARS. But the agency and other scientists agree that more work needs to be done to be certain. Scientists know that other coronaviruses have a high rate of mutation and so they say that it is far too soon to know whether the SARS virus will change to cause milder, or even more severe, illness, or become a seasonal disease, like influenza and other coronaviruses. Dr. [Earl G. Brown] said that studying animals in China to trace SARS back to its possible origin would be a formidable task. Countless animals would have to be swabbed for viruses, and the samples would then have to be cultured, sequenced and compared. And since it is also possible that SARS came from a mutated human coronavirus, researchers would have to search for human viruses as well

Calculating death rates for new diseases like SARS is notoriously difficult for epidemiologists, particularly if there is no definitive diagnostic test, as is the case with SARS. The final death rate will not be known until the epidemic has run its course. Moreover, death rates can vary from one set of patients to another, depending on factors like the amount of virus transmitted, where it entered the body, and the functioning of an individual's immune system. On Tuesday, the same study that found a higher death rate in Hong Kong suggested that the incubation period for SARS might be as long as 14 days. But that analysis, published in the medical journal Lancet, was based on only 57 cases. On Wednesday, the WHO stood by its 10-day estimate. That figure was determined by reviewing cases in which the patient had a single documented exposure to a known SARS patient in Canada, Europe or Singapore, the agency said

Unless the numbers fall drastically, SARS would be among the infectious diseases with the highest death rates. Until now, fatality rates reported by the World Health Organization had ranged from 2 percent, when the epidemic was first detected in March, to 7.2 percent. The new findings come from a statistical analysis of 1,425 patients suspected of having severe acute respiratory syndrome who were admitted to Hong Kong hospitals from Feb. 20 to April 15. Overall, their mortality rate was estimated to be as high as 19.9 percent. The principal authors of the study from Imperial College, the University of Hong Kong, the Chinese University of Hong Kong and the Hong Kong health department said their findings underscored that SARS is a serious threat to the public and that health officials and workers must act to contain it. The authors credited Hong Kong's efforts to reduce the time from the onset of symptoms to the isolating of patients in hospitals as an important step in controlling the disease. Reducing the time did not affect the course of the illness in individual patients, they said, but speeding the isolation process reduced the period when they could transmit the virus to others. The study, said Dr. Michael Osterholm, an expert on infectious disease at the University of Minnesota, 'looks solid and provides an important source of information about the evolving epidemic.' Dr. Klaus Stoehr, the scientific director of the SARS investigation for the World Health Organization, said in an interview that the agency was reviewing the new data and the statistical models used to obtain them. 'The case-fatality rate can be calculated in many ways and can depend on various scenarios,' Stoehr said

Calculating death rates for new diseases like SARS is notoriously difficult for epidemiologists, particularly if there is no definitive diagnostic test, as is the case with SARS. The final death rate will not be known until the epidemic has run its course. Moreover, death rates can vary from one set of patients to another, depending on factors like the amount of virus transmitted, where it entered the body, and the functioning of an individual's immune system. Yesterday, the W.H.O. stood by its 10-day estimate. That figure was determined by reviewing cases in which the patient had a single documented exposure to a known SARS patient in Canada, Europe or Singapore, the agency said. The United States has begun to take steps to patent the SARS virus and its genes because if others patent them, Dr. Julie L. Gerberding, director of the Centers for Disease Control and Prevention in Atlanta, said, this country ''could be locked out of the opportunity'' to develop vaccines and diagnostic tests. ''By taking steps to secure patent rights,'' she said, ''we assure that we will be able to continue to make the virus and the products from the virus available in the public domain.''

Mortality rates are bound to change somewhat as the epidemic continues. But unless the numbers fall drastically, SARS would be among the most lethal infectious diseases. Until now, SARS death rates reported by the World Health Organization had ranged from 2 percent, when the epidemic was first detected in March, to 7.2 percent. The new findings come from a statistical analysis of 1,425 patients suspected of having SARS who were admitted to Hong Kong hospitals between Feb. 20 and April 15. Overall, their mortality rate was estimated to be as high as 19.9 percent. By contrast, the influenza of the 1918 pandemic, which killed tens of millions of people worldwide, had an estimated mortality rate, overall, of 1 percent or less. The principal authors of the study, from the Imperial College in London, the University of Hong Kong, Chinese University of Hong Kong and Hong Kong health department, said their findings underscore that SARS is a serious threat to the public and that health officials and workers must act to contain it

The new findings come from a statistical analysis of 1,425 patients suspected of having SARS who were admitted to Hong Kong hospitals from Feb. 20 to April 15. Over all, their mortality rate was estimated to be as high as 19.9 percent. By contrast, the influenza pandemic of 1918, which killed tens of millions of people worldwide, had an estimated mortality rate, over all, of 1 percent or less. Yesterday, the W.H.O. said the number of new SARS cases in Hong Kong had steadily declined, which they said suggested that the outbreak there had reached a peak. So far, Hong Kong has reported 1,646 probable cases and 193 deaths, which would mean that the death rate is 11.7 percent. The authors said it might turn out that the incubation period depended on where the SARS virus entered the body. Health officials say that most cases result from the spread of droplets from coughs and sneezes. The SARS virus can survive on surfaces for up to four days, and although scientists have not proved that transmission has occurred through such contamination, Hong Kong officials suspect that a big outbreak at an apartment complex there was spread through sewage

Mortality rates are bound to change somewhat as an epidemic continues. But unless the numbers fall drastically, SARS would be among infectious diseases with the highest death rates. Until now, fatality rates reported by the World Health Organization had ranged from 2 percent, when the epidemic was first detected in March, to 7.2 percent. The new SARS findings come from a statistical analysis of 1,425 patients suspected of having SARS who were admitted to Hong Kong hospitals from Feb. 20 to April 15. Overall, their mortality rate was estimated to be as high as 19.9 percent. On Tuesday, the WHO said the number of new SARS cases in Hong Kong had steadily declined, which officials said suggested that the outbreak there had reached a peak. So far, Hong Kong has reported 1,646 probable cases and 193 deaths, which would mean that the death rate was 11.7 percent

Laboratory tests found that detergents were far less effective in killing the SARS virus, [Klaus Stoehr] said. The SARS virus is quite sensitive to changes in temperature, according to researchers at the National Institute of Infectious Diseases in Tokyo. At body temperature, the SARS virus survived less than four days, the Japanese researchers found. But it survived at least four days at refrigerator temperatures and seems to be able to survive indefinitely at temperatures in a deep freezer. On plastic surfaces at room temperature, the virus could survive for two days, researchers said. The SARS virus is a new member of the coronavirus family, which includes viruses that can cause the common cold in humans and many more serious diseases in animals. SARS researchers have tried to extrapolate findings from known viruses in dealing with SARS. But many aspects of the new findings are surprising. For one thing, they show that the SARS virus is less stable at room temperature than other coronaviruses, particularly those that infect humans, Stoehr said

A look back shows striking differences in the way public health officials reacted to AIDS and SARS -- and it shows how much health agencies' quick response to SARS owes to the lessons of AIDS. The AIDS and SARS viruses damage the body in different ways. AIDS slowly attacks the immune system; symptoms take about 10 years to appear. SARS is faster: it takes 2 to 10 days, possibly as long as 13, from exposure to the onset of symptoms. Initially, each virus primarily affected young adults -- gay men for AIDS and health workers of both sexes for SARS. Because AIDS spreads through sexual activity, contaminated needles among drug injectors and from mothers to children, it still afflicts mostly young adults. But SARS spreads indiscriminately, and patients have varied more widely in age. But, for unknown reasons, SARS has largely spared children