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May 10, 2018

Responding To: Addressing Pandemics and Global Migration

At the Frontier of the Global Battle Against Emerging Infections: Managing Avian Influenza in Guangdong, China

Professor Michael Stoto, Georgetown University

Guangdong province, China stands at the frontier of the global battle against emerging infections, especially avian influenza.  The densely populated province of 110 million inhabitants includes several mega-cities side-by-side with small-scale agricultural areas.  Guangdong residents consume more chicken than other areas of China and prefer to purchase it at “wet” (live poultry) markets, which can accelerate the emergence of pandemic strains of the influenza virus and transmission to humans.  And, as a major manufacturing region that serves as the hub of the Maritime Silk Road, Guangdong houses many international immigrants and travelers, especially from Africa.  A more potent powder keg for the emergence of a new strain of influenza capable of starting a global pandemic would be hard to find. 

Guangdong has successfully developed a public health approach for addressing these challenges that is a model for other areas of China, as well as other countries, to consider.  Guangdong’s public health “system” is based on a tiered system of Centers for Disease Control (CDCs) at the national, provincial, district, and community level.  At each level, these CDCs work with a complex hierarchy of public health clinics, infectious disease hospitals, and other governmental agencies, including those that deal with food and agriculture.  The province’s experience with the H7N9 avian influenza strain, which emerged in China in 2013, illustrates how this system works.

The first component, real-time comprehensive surveillance, is based on a web-based system that collects case reports from community clinics and hospitals and a laboratory network of CDC and hospital microbiological labs.  The CDCs also conduct environmental surveillance at poultry farms, wet markets, and similar locations, and monitors high-risk groups such as those who work at these locations.  The surveillance system provides regular epidemiology reports documenting the number, demographic characteristics and geographical location of cases, as well as the case fatality rate.  The CDC also conducts event-based media surveillance (monitoring e-mail, WeChat & MMS).

Building on case surveillance and the laboratory network, the Guangdong CDC prepares timely scientific risk assessments.  Assessments are prepared on a regular schedule for key pathogens, and rapid, in-depth risk assessments are conducted for emergencies. 

The surveillance data and risk assessments also enable a rapid and effective response to manage disease outbreaks.  Guangdong’s live poultry market management strategy to control human H7N9 risks, for instance, has four response levels.  The routine prevention level relies on the “three-one” policy: cleaning and disinfection every day, one thorough cleaning every week, and one market closure day per month.  The environmental control level includes temporary market closures and disinfection. Evidence of scattered incidence of human infection triggers market disinfection and poultry quarantine.  And consistent incidents lead to the temporary closure of all markets in the region.

More generally, Guangdong uses a four-level epidemic prevention and control and risk management strategy for H7N9 avian influenza.  Implementation depends in part on available resources.  Guangzhou and most of Guangdong province are at the “control risk” level.  This involves disinfecting poultry cages and transportation vehicles, strengthening the management of wholesale live poultry markets, having a designated slaughterhouse, reconditioning live poultry markets, and strict implementation of the Three-One-Zero Policy at poultry markets.  Shenzhen city in Guangdong (as well as neighboring Hong Kong), are at the highest level: “eliminate risk.”  This includes stronger management of poultry farms, centralizing slaughterhouses and markets, strengthening the management of wholesale live poultry markets, closing live poultry markets in urban and rural areas, and relying on refrigerated fresh poultry products. 

CDC’s scientific evaluations also provide the basis for active and accurate intervention.  For example, spatial phylogenetic analysis of viral samples indicated that the third-wave outbreaks in central Guangdong in 2015 most likely resulted from local virus persistence rather than introduction from elsewhere, suggesting that live-poultry market interventions cannot completely halt H7N9 virus persistence and dissemination [1].

Finally, all of this relies on multilateral communication.  Within China, the Guangdong CDC is part of the National Acute Infectious Diseases Prevention and Control Public Health Emergency Response Team and PulseNet China.  The Guangdong Area Central Laboratory conducts research projects resulting in scientific collaboration.  Internationally, Guangdong CDC is a WHO Emerging Infectious Diseases Surveillance, Research and Training Collaborating Center and collaborates with the Global Public Health Intelligence Network, the Global Outbreak Alert and Response Network Member.  The Guangdong CDC also collaborates with neighboring Hong Kong and Macau by sharing monthly surveillance reports and disease specific reports.  They also participate in an annual meeting that facilitates collaboration and provides an opportunity for public health professionals to discuss potential threats and intervention methods.

[1]  Wu, J., et al., Effect of live poultry market interventions on Influenza A(H7N9) virus, Guangdong, China.  Emerging Infectious Diseases, 2016, 22(12):2104-2112.

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