SARS continues to cause concern

Toronto experiences more outbreaks and deaths as the mysterious disease spreads

With 10 known deaths, and nearly 200 known cases, severe acute respiratory syndrome (SARS) is sweeping over Toronto and the vicinity at a concerning speed. And while doctors are confident that the problem is under control, and that new cases will begin decline because of steps taken, many wonder if the situation was too slow in detection and handling.
SARS was first identified in Toronto in early March, and results concluded that patients worldwide ranged from 24 to 78 years old, and that 60 percent were men. Transmission occurred only after close contact and the most common presenting symptoms were fever (in 100 percent of cases) and malaise (in 70 percent), followed by nonproductive cough (in 100 percent) and dyspnea (in 80 percent) associated with infiltrates on chest radiography (in 100 percent).
The international media have played an around-the-clock part in communicating breaking news to the public by television, radio, print publications, and the Internet. Speed of scientific discovery and speed of communication are hallmarks of the response to SARS and reflect amazing achievements in science, technology, and international collaboration.
However, despite these advances, a very sobering question remains - are we fast enough? Can we prevent a global pandemic of SARS? The epidemic is progressing rapidly in many parts of Asia. The situation in mainland China is not entirely clear, but the available information strongly suggests that there is ongoing transmission in at least some provinces.
The epidemic is still expanding in Hong Kong, despite heroic measures on the part of the government to curtail its spread. Clusters of cases in community settings such as hotels and apartment buildings in Hong Kong demonstrate that transmission can be extremely efficient. Likewise, very high attack rates among health care workers in Hanoi, Vietnam, and in hospitals in Hong Kong document the highly contagious nature of this virus. Many household contacts have become ill.
Concern is mounting about the potential for spread in schools, the workplace, airplanes, and other crowded areas. New cases among travelers from affected areas continue to emerge and have led to infections in household contacts and health care personnel in many countries, including the United States and Canada.
The epidemic of SARS is apparently only months old, and it is entirely too soon to predict its ultimate scope or magnitude. According to the New England Journal of Medicine, epidemiologic evidence indicates that the transmission of SARS is facilitated by face-to-face contact, and this still appears to be the most common mode of spread. Some evidence suggests that a few persons may be especially infectious and that most others are less likely to serve as sources of infection, but this concept is still speculative.
Airborne transmission may have a role in some settings and could account for the extensive spread within buildings and other confined areas that has been observed in some places in Asia. Certainly, airborne transmission will make containment of the epidemic much more challenging.
If the new coronavirus proves to be the cause of SARS, fomite or other modes of transmission could also be relevant, since coronaviruses can survive on contaminated objects in the environment for at least a few hours and have been isolated from the stool of some animals. Despite our long experience with other viral respiratory infections, there is no proven, successful population-based strategy for their prevention. Even when we have an effective vaccine, as in the case of influenza, annual infection rates and attributable mortality remain very high.
If SARS transmission evolves to mimic that of influenza, containment may well be impossible without vaccination, prophylaxis, or treatment.
There is reason to be optimistic about future control measures. Vaccines are successful in preventing coronavirus infection in animals, and the development of an effective vaccine against this new coronavirus is a realistic possibility. Likewise, novel antiviral agents, antiviral drugs in development, or existing licensed drugs could be found to provide effective prophylaxis or treatment. But can we make these products available fast enough to prevent an extensive global outbreak?
Recent experience with the advances in measures against bioterrorism suggests that the pace of development can be dramatically accelerated. However, potential rate-limiting steps include the development of suitable animal models to demonstrate efficacy, the time necessary to demonstrate the safety of any new product in adults and children, and the time and resources needed to increase production to meet global market needs.
The emergence of SARS presents formidable global challenges. If we are extremely lucky, the epidemic will be curtailed, develop a seasonal pattern that will improve prospects for regional containment, or evolve more slowly than it has in this early stage. If the virus moves faster than our scientific, communications, and control capacities, we could be in for a long, difficult race.

Publication Date: 2003-04-13
Story Location: http://tandemnews.com/viewstory.php?storyid=2606