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SARS gives U.S. practice in fighting new pathogens
Incidence in Asia still a concern
The worldwide outbreak of severe acute respiratory syndrome (SARS) has put pharmacists and other health care professionals on alert. The incidence of SARS cases in the United States seems to be contained, but health officials warn that the threat is still real until Asia is able to control the virus.
On May 8, the World Health Organization (WHO) in Geneva, Switzerland, reported a cumulative total of 7,053 probable SARS cases and 506 deaths in 29 countries. The most deaths were reported in mainland China (224), Hong Kong (208), and Singapore (204). Because of the cases in those areas, the WHO recommends as of May 7 that people consider postponing all but essential travel to several areas of China, namely: Beijing, Hong Kong, Guangdong, Inner Mongolia, Shanxi, Taipei, and Tianjin.
In addition, the WHO has revised its initial estimates of the case fatality ratio of SARS. The revision is based on an analysis of the latest data from Canada, China, Hong Kong, Singapore, and Vietnam. The estimate of case fatality ratio of SARS ranges from 0% to 50% (depending on the age group affected), with an overall estimate of 14-15%.
Broken down by age groups, the case fatality ratio is estimated to be:
In contrast to other parts of the world, the United States has contained the outbreak within its borders well, so far. As of May 7, the Centers for Disease Control and Prevention (CDC) reports that a total of 328 SARS cases have been reported from 38 states, of which 265 (81%) were classified as suspect SARS, and 63 (19%) were classified as probable SARS (more severe illnesses characterized by the presence of pneumonia or acute respiratory distress syndrome). Of the 63 probable SARS patients, 42 (67%) were hospitalized, and three (5%) required mechanical ventilation. No SARS-related deaths have been reported in the United States.
Of the 63 probable SARS patients, one (2%) was a health care worker who provided care to a SARS patient, and one (2%) was a household contact of a SARS patient. The remaining 61 (97%) probable SARS patients had traveled to areas with documented or suspected community transmission of SARS during the 10 days before illness onset.
This shows that infection control practices do work in this country, says Michael Rybak, PharmD, MS, FCCP, president of the Society of Infectious Diseases Pharmacists in Austin, TX, and professor of pharmacy and medicine at the Eugene Applebaum College of Pharmacy and Health Sciences at Wayne State University in Detroit.
"The lesson to be learned here is that when there is an outbreak of a communicable disease that can spread rapidly through a population, we seem to be able to put the right people and the right instructions and guidelines into play that contain such an outbreak."
Others also credit good fortune. "I think good fortune in this case is a consequence of a prepared public health system and a prepared clinical community, but also, we have perhaps been fortunate to some extent in that a particularly infectious patient has not slipped through the cracks or had a long period of time to be exposed to others in the home or in the health care setting," Julie Gerberding, MD, MPH, director of the CDC, told reporters at a May 6 telebriefing.
Researchers had been concerned that the SARS virus had begun to mutate. That was especially troublesome to clinicians who have worked with infectious pathogens such as HIV. "Any bacteria or virus that divides and mutates is a significant concern," says Frank Romanelli, PharmD, BCPS, assistant professor of pharmacy and clinical specialist in HIV/AIDS at the College of Pharmacy and College of Health Sciences at the University of Kentucky in Lexington. "The ability of [the HIV] virus to mutate has made it a very formidable pathogen in terms of drug and vaccine design."
The first major study of the genome of the SARS virus, however, shows that it has not mutated significantly in its spread to different countries. Health officials were both pleased with the news because this might increase the possibility of developing a vaccine, and concerned since SARS seems to stay strong as it continues through successive generations. The study was published in the May 10 edition of the medical journal Lancet.