Severe Acute Respiratory Syndrome (SARS), a new, highly infectious viral disease, was firstidentified by the World Health Organization (WHO) in February 2003. It is believed to have hadits beginnings in China's Guangdong Province in November 2002. A respiratory disease that causesflu-like symptoms which may progress to pneumonia, SARS has an average fatality rate of 15%. Between November 2002 and July 2003, a total of 8,437 cases and 813 deaths were reported in 31countries. (1) While the overall numbers are not high by comparison with other serious infectious diseases, the speed and distance with which SARS spread raised an alarm over the potential risks tointernational public health. Containment appears to be working; however, there are fears thatanother SARS outbreak might take place during the regular influenza season later in 2003. Thisreport reviews the global response by WHO and those countries most affected. It also examines thechallenges that may lie ahead should another outbreak of SARS (or another unknown infectiousdisease) occur. (2) Since late February, when WHO first identified the outbreak of what later became known asthe Severe Acute Respiratory Syndrome (SARS), it has played a key role in the global response tothe disease. SARS is a striking example of the risks to international public health posed by suchinfectious diseases. It also highlights the need for appropriate mechanisms of containment,particularly as global travel has become the primary means of spreading the disease around theworld. Following its initial assessment, WHO made containment of SARS its main goal. "Despite the lack of understanding about the disease, its cause, and future evolution, the need was great tointroduce a series of emergency measures to contain SARS outbreaks in the affected areas andprevent further international spread, thus reducing opportunities for the new disease to establishitself." (3) Although WHO's representative in China,Henk Bekedam, reportedly said on June 5, 2003that the outbreak of SARS had reached its peak worldwide, (4) WHO continues to stress the importanceof sustaining international public health measures against SARS and working towards eliminatingit as a public health threat. The SARS outbreak may reveal valuable lessons about the effectivenessof WHO's surveillance and response systems, and its capacity to respond to similar outbreaks in thefuture. Examining the evolution of SARS also demonstrates the chains of transmission and role ofthe WHO in responding to unfolding events. Although WHO led an unprecedented global collaborative effort to contain SARS, the U.S. Centers for Disease Control and Prevention (CDC) also played a key role in the global partnership. For more information on the role of the CDC in relation to SARS, see CRS Report RL31937 , SARS:Public Health Situation and U.S. Response . The World Health Organization (WHO), established in 1948, is the U.N. system's authority on international public health issues. It assists governments in improving national health services andin establishing worldwide standards for foods, chemicals, and biological and pharmaceuticalproducts. WHO concentrates on preventive rather than curative programs, including efforts toeradicate endemic and other widespread diseases, stabilize population growth, improve nutrition,sanitation, and maternal and child care. WHO works through contracts with other agencies andprivate voluntary organizations. The United States has been a member of WHO since 1948. The WHO policy making body is the World Health Assembly, composed of all 192-member states. It meets annually in May to decide the overall direction of the Organization and the generalprogram for a specific period, and to adopt the two-year budget. Decisions are made by majorityvote, except for decisions on the budget that require a two-thirds vote. There is no veto provision. The Assembly elects the Director General as well as the 32 member states who designate personsto serve on the Executive Board. The Executive Board meets twice a year to review the work ofWHO in more detail and prepares issues for consideration by the Assembly. Ten to twelve membersof the Board are replaced every year. The United States has been a member on the Executive Boardthree out of every four years. The Global Outbreak Alert and Response Network (GOARN). In April 2000, WHO formally established the Global Outbreak Alertand Response Network (GOARN) which brought together 112 institutions and networks of peopleand technical resources to respond to disease outbreaks of international concern. This global healthsecurity network provides not only an operational framework, drawing on data, expertise, and skill,but also aims to standardize the international response. (5) It relies on its partners and agreed standardsof practice in responding to potential threats, which may include emerging diseases and theintentional use of biological agents. In four years, between January 1998 and March 2002, GOARNexamined 538 such cases in 132 countries. (6) The Global Public Health Intelligence Network (GPHIN). WHO also relies on the Global Public Health Intelligence Network(GPHIN), which is a customized search engine that tracks Internet communications. This systemproved to be very useful in picking up telecommunicated alerts in China. The system is also usefulto WHO in clarifying or refuting information that may create disruption or panic. Other tools includegeographical mapping technology and an event management and tracking system that provides anoverview of operations. It was clear that SARS presented a serious global threat. Lack of information about the cause and evolution of the new disease made its potential impact unknown. WHO concluded that the viruscomes from a strain likely to include frequent mutations and links to animal species, withimplications for the likelihood of establishing endemicity and underlining the importance of findingthe means to control or contain it. Several factors were deemed critical in this analysis: The symptoms are non-specific and common; The symptoms can be severe and some patients require intensive care forrespiratory failure; The disease spreads easily from one location to another via air travel asdemonstrated in transmission patterns from the initial outbreak in Asia to other regions, such asNorth America and Europe; There is no vaccine or treatment yet available and diagnostics tests are oflimited use. A number of antivirals are not effective; The causative agent is not well understood, so the potential for continuedspread remains; Certain cases may contribute to the rapid spread ofinfection; Hospital staff, who are a vital link to the control of infection, aredisproportionately affected as are other close contacts of the patients; The disease requires intensive treatment in isolation and is a burden on healthcare systems. (7) By comparison to SARS, except in the case of HIV/AIDS, other new diseases that have emerged in the last few decades have not presented the same combination of factors that pose sucha heavy global risk to international health. Some of these diseases have not sustained stronghuman-to-human transmission, others have relied on food or a vector (such as mosquitos) fortransmission, and still others have had an identifiable, often containable, geographic location. Once the severity of the disease was recognized, in February and March 2003, WHO took aggressive action. Examining the factors outlined above and the chronology of events unfolding inChina, Hong Kong, Vietnam, and Toronto, it identified international travel as a primary means ofspreading the virus. It also concluded at the time that some people might be highly infectious, or"super spreaders". Identifying these individuals could be critical to the control of the disease. (8) OnMarch 15, 2003, WHO issued emergency travel recommendations as a global alert and response tointernational travelers, health care professionals, and border authorities. Later in March itrecommended screening passengers at airports coming from areas with recent local transmission andgave advice to airlines on appropriate procedures if a case was suspected during flight. In April andMay, on several occasions, the WHO issued its most stringent travel advisories recommending thepostponement of all but essential travel to areas considered high risk for SARS,. (9) WHO also quickly moved to set up systems for -- and increase awareness of the need for -- immediate isolation and quarantine of those with or suspected of having SARS. In addition, it beganthe detailed work of contact tracing to find the source of the spread. These procedures along withsimple diagnostics and screening all contributed to the ongoing containment effort. The response to SARS placed heavy demands on WHO and its GOARN partners. Time was very much of the essence. WHO pulled together a comprehensive network, including mobilizinga response on the ground, providing resources and supplies, monitoring and reporting, andestablishing scientific and medical collaboration. The WHO issued travel procedures to prevent andmanage probable cases of SARS. (10) It establisheda collaborative multi-center research project onSARS and brought together clinicians for SARS diagnosis and treatment. (11) It also developedguidelines, recommendations, and descriptions concerning case definitions, case management,laboratories, biosafety, blood safety, epidemiology, mass gatherings, and goods and animals fromSARS-affected areas. (12) An urgent plan for the operational response to SARS was developed and implemented. This included providing expertise and supplies in SARS-affected areas and hospitals, and "in the air"through technology to bring the best minds to the collaboration required. This plan resulted in: A global alert Rapid case identification Global reporting system and verification Regular updates and advice International field support and logistics coordination Epidemiological and clinical networking Laboratory network (13) Through this network, and daily conference calls, epidemiologists were able to discuss cases, refine their definitions, examine chains of transmission, track progress, and increase theirunderstanding of what worked best where. Similarly, individuals working in the clinical networkwere able to share experiences with different forms of treatment, examine the possible reasons forthe range of individual responses to the disease, and develop guidelines for infection control. Thenetwork of the laboratories enabled many scientists to work together to come up with theidentification of the SARS virus. Scientists have much to learn about SARS, including understanding the evolution of the disease, designing early detection, prevention and treatment strategies, and establishing effectivesurveillance systems.