In response to student, faculty, and staff interest in learning more about the public health threat posed by the emerging disease known as Severe Acute Respiratory Syndrome or SARS, the Mailman School of Public Health held a briefing on April 23. Dr. Scott Hammer, the Harold C. Neu Professor of Infectious Diseases at P&S and professor of epidemiology at the Mailman School of Public Health, and Dr. Stephen Morse, associate professor of epidemiology at Mailman and director of the Mailman Center for Public Health Preparedness, spoke about the science of the epidemic, the safety of travel, how the disease is spread, potential treatment options, and the latest findings from the Centers for Disease Control and Prevention and the World Health Organization. What follows is a condensed selection of questions posed at the briefing and answers provided by Drs. Hammer and Morse.
What is SARS?
Dr. Hammer: SARS is caused by a newly identified member of the coronavirus family, but how it came to infect humans is unclear. The virus's genetic code has been sequenced by the Centers for Disease Control and Prevention and another group in Canada. Dr. W. Ian Lipkin, professor of epidemiology at Mailman and neurology at P&S, also is sequencing the virus and working to develop laboratory tools for rapid identification of the virus.
Dr. Hammer: Stay informed and defer elective travel to areas with community transmission such as China, Hong Kong, Hanoi, and Singapore. The World Health Organization has added Toronto to that list but the CDC's recommendation is less stringent about Toronto and Canada, in general. To contract SARS, apparently you have to go to a geographic area where SARS is active or have close contact with a SARS patient. If you experience either of those, watch for fever and respiratory symptoms. You must report to the Occupational Health Service to receive clearance to return to work, even if you have no symptoms, as a precautionary measure. If you do develop symptoms, you should call Occupational Health or the Emergency Department to arrange for a medical evaluation. The medical advice to people who have had close contact with a person with SARS is a voluntary quarantine of 10 days. Always practice good hand hygiene, that is, wash hands regularly.
Dr. Morse: The World Health Organization has added Toronto to the list of places where elective travel should be deferred as a way to pre-emptively stop the spread of SARS. The addition is controversial because some health officials in Toronto feel the city is still a safe place to travel to. The risk, even for someone living in Toronto, is very small.
How can people get the latest information on the disease?
Dr. Hammer: I recommend checking these Web sites: the CDC (www.cdc.gov); the New York City Department of Health and Mental Hygiene (www.nyc.gov/health); the World Health Organization (www.who.int/en/); and ProMED-mail, a site by the International Society for Infectious Diseases (www.promedmail.org) that Dr. Morse started as a global early warning system to track outbreaks of emerging infectious diseases.
There are two definitions of SARS. Why?
Dr. Hammer: The CDC has developed two definitionsa suspect case and a probable caseas a way to collect information on all cases. The suspect case is defined as a respiratory illness of unknown origin with onset since Feb. 1 with a temperature of more than 100.4 degrees Fahrenheit; one or more respiratory symptoms such as cough, shortness of breath, difficulty breathing or hypoxia; and travel within 10 days of symptom onset to an area with community transmission of SARS or close contact within 10 days of a person with SARS. A probable case is a suspect case with either X-ray evidence of pneumonia or respiratory distress syndrome or autopsy findings with respiratory distress syndrome without an identifiable cause.
As of April 23, there were 231 total cases in the United States, with 192 suspect cases, 39 probable cases and zero deaths. In New York City, there were 15 total cases, with 13 suspect and two probable cases.
What is the treatment for a SARS patient?
Dr. Hammer: SARS patients are to be immediately isolated to prevent virus transmission. A full clinical and laboratory investigation must be done. Patients are given supportive care, such as fluids, but it is uncertain if any medications are effective. Some countries are treating SARS patients with antivirals, such as ribavirin, and steroids, but there is no evidence that they are effective.
What about a vaccine for SARS?
Dr. Hammer: The issue is whether the virus stays the same or changes. If it stays the same and does not recombine with other viruses, we have a decent chance of developing a vaccine.
Dr. Morse: The other issue with vaccines is that generally there has to be economic incentive for a vaccine to be developed. Traditionally, resources for vaccine development are limited.
How do you rate the response of public health organizations?
Dr. Morse: The public health system, including the CDC and the WHO, has responded admirably to the challenge, even though it got off to a slow start because of delays in other countries, such as China, in the reporting of SARS cases. I hope people now understand the importance of reporting outbreaks early so we can work to contain them.
Why did SARS start in China? And why do influenza strains tend to come from this area?
Dr. Morse: We're trying to figure out why SARS started in Asia and also why annual influenza epidemics come from Asia. SARS possibly could have been introduced from another species such as rats or birds. We do know that pandemic influenza often seems to start in the same area. Pandemic influenzas, we think, start in birds or fowl, jump to pigs, and then to humans. Hypothetically, the farming system in China, which often has duck ponds and pig farms in close proximity, may be serving as an open-air laboratory of viral reassortment that can make new pandemic influenza strains. In the case of SARS, of course, it is important for us to discover its origin so we can reduce human exposure to the virus.