Conference organized by:

Center for Biosecurity of UPMC

World Health Organization Communicable Disease Surveillance and Response Office

Conference sponsored by:

The Nuclear Threat Initiative

The Global Response to Emerging Epidemics
Presenter: David Heymann, M.D.

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Dr. Heymann reviewed the history of international health regulations and the role of the WHO in global disease surveillance and control, including detailed discussion of the events surrounding the global response to SARS and the lessons learned from that experience.

Since as early as the 14th Century, when ships were kept offshore in the Venice harbor to prevent the spread of plague, quarantine and international health regulations have provided a framework for global disease surveillance and response. The first International Health Regulations (IHR), which were drafted in 1969, are a nonenforcable framework to prevent the international spread of infectious diseases, rely upon passive reporting systems, and resulted in late detection and response. Global outbreaks now require early detection and early response.

In preparing for a revision of the IHR, WHO has linked more than 120 institutions through country offices in a partnership for global alert and response to infectious diseases, and most of the WHO's information no longer comes from countries. Now, NGOs, information networks like ProMED, the GPHIN, FluNet, and other informal networks and systems provide 77% of the reports to the WHO. If a reported public health risk is determined to be of urgent international importance then, in addition to national containment, collaborative risk-based public health measures are identified and recommended by the WHO.

Heymann reviewed how this system worked during the the SARS epidemic of November 2002 through May 2003. Information initially collected about respiratory infections among healthcare workers in China, the recognition of a syndrome of atypical pneumonia and respiratory failure in a 48-year old businessman with history of previous travel to China and Hong Kong, and subsequent reports of outbreaks in Viet Nam and Hong Kong, led to the first global alert for SARS in March 2003. This reporting was facilitated by the heightened surveillance already underway through FluNet, a network of laboratory partners, because of concern about avian influenza.

By March 15, 2003 it was clear that there was an outbreak of atypical pneumonia with rapid progression to respiratory failure from which no one had yet recovered, that health care workers appeared to be at greatest risk, and that the cause was likely an infectious agent, but it had not been identified. Antibiotics and antivirals did not appear to be effective, no vaccine existed, and the disease was spreading internationally within Asia and to Europe and North America. A decision was made to issue a second global alert and institute a containment program. A case definition and clinical description of cases, X-ray findings, and geographic links were provided. The disease was named severe acute respiratory syndrome (SARS) and international travelers were informed to notify a health worker if they returned from one of the areas where an outbreak was occurring and developed symptoms compatible with the case definition. Strategies to increase the power of epidemic control included the use of telephone and video conferencing and other real time electronic communications among members of the Global Outbreak Alert and Response Network (GOARN), which included 115 experts from 26 institutions and 17 countries. On March 27, it was recommended that airlines in areas with local transmission of SARS actively screen departing passengers using two questions: 1. Did a traveler have a history of contact with a person with SARS? 2. Did a traveler have a persistent fever, cough, or other signs and symptoms compatible with SARS?

In Hong Kong, health declarations, temperature checking, medical posts on site, and "stop lists" at immigration control points were instituted. SARS continued to spread internationally by air travel in infected passengers. Some cases could not be traced to known contacts despite intensive contract tracing and environmental transmission was suspected in the Amoy Gardens apartment complex in Hong Kong. Additional recommendations were issued, requesting that international travelers postpone non-essential travel to certain areas with outbreaks of more than 60 active cases and 5 new cases reported each day. By this time the clinical features of SARS, its natural history and descriptive epidemiology were well characterized. Within a month, the SARS corona virus was identified, fully sequenced, and described. SARS was clearly a point epidemic with an index case from Guangdong China with international amplification and transmission by guests at Hotel M, Hong Kong between February 21 and March 26, 2003. The outbreak was rapidly brought under control with cases tailing off worldwide by June 2003.

Important lessons were learned from the SARS experience:

• Healthcare workers and/or primary responders are at greatest risk of emerging infections.
• Collective action can stop international spread of an emerging infection.
• Airport screening measures are of uncertain effectiveness, but were useful in restoring confidence in business and other international travelers.
• International travelers accept travel recommendations.
• Collaboration between health and other government sectors, such as when public health and law enforcement systems work together, is synergistic.
• Proven epidemiological strategies should be trusted.
• Emerging infections are costly to economies.
• Global alert and response with multiple partners is required to detect and contain internationally spreading outbreaks.
• Internationally spreading outbreaks can overwhelm health systems because of the effect on healthcare workers and the insufficient infrastructure and surge capacity.
• Electronic, telephone, video conferencing can facilitate the work of scientists and public health experts.
• An element of good luck is required.

In 2005, case identification through surveillance in areas at risk for SARS, collaborative studies in Guangdong Province to identify animal reservoirs and risk factors for transmission to humans, and research and development for diagnostics, vaccines, and antivirals continue. Global surveillance for influenza and other emerging infectious diseases is underway to identify the next major emergence of a new influenza strain or other infection of international importance. Recent avian influenza outbreaks have successfully breached the species barrier, and there is concern that non-immunized humans will serve as the intermediate host.

Dr. Heymann concluded from his experience with SARS that the best investment today is in preparation for and response to naturally occurring infectious diseases as this knowledge and experience will help in the event of a deliberately spread infection.

- Summary by Richard Waldhorn, M.D.

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