Avian influenza in China

Key facts

  • Avian influenza (AI), commonly called bird flu, is an infectious viral disease of birds.
  • Most avian influenza viruses do not infect humans; however some, such as H5N1, have caused serious infections in people.
  • Outbreaks of AI in poultry may raise global public health concerns due to their effect on poultry populations, their potential to cause serious disease in people, and their pandemic potential.
  • Reports of highly pathogenic AI epidemics in poultry can seriously impact local and global economies and international trade.
  • The majority of human cases of H5N1 infection have been associated with direct or indirect contact with infected live or dead poultry. There is no evidence that the disease can be spread to people through properly cooked food.
  • Controlling the disease in animals is the first step in decreasing risks to humans.

The situation

  • High Pathogenic Avian Influenza H5N1 is in the list of category B of notifiable diseases to be reported according to the Law of Communicable Diseases Prevention and Control in China, but this disease is treated as category A of notifiable diseases.
  • The first outbreak in humans occurred in 1997 in Hong Kong in which 18 human cases were infected (6 fatal) with avian influenza H5N1. However, H5N1 was identified in 1996 in geese in Guangdong, China
  • This 1997 outbreak was contained until 2003 during which two human H5N1 cases (one fatal) were confirmed in Hong Kong.
  • The first human H5N1 case in mainland China probably occurred in 2003 during the SARS outbreak but was only confirmed retrospectively in 2006.
  • According to the Ministry of Health, from 2003 to 20 September 2012, the number of cases reported in China was 43, including 28 fatalities.
  • The primary risk/exposure factor for human infection appears to be direct or indirect exposure to infected live or dead poultry or contaminated environments (for example visiting live poultry markets).
  • Controlling circulation of the H5N1 virus in poultry is essential to reducing the risk of human infection.
  • Beside the human H5N1 AI cases, there were five H9N2 cases found in mainland China in 1998 and 1999, respectively, and three human H9N2 AI cases reported in Hong Kong in 1999 and 2003 respectively.

Influenza pandemics

  • Influenza pandemics (outbreaks that affect a large proportion of the world) are unpredictable but recurring events that can have health, economic and social consequences worldwide.
  • An influenza pandemic occurs when key factors converge: an influenza virus emerges with the ability to cause sustained transmission from human-to-human, and there is very low, or no, immunity to the virus among most people.
  • In the interconnected world of today, a localized epidemic can transform into a pandemic rapidly, with little time to prepare a public health response to halt the spread of illness.

Progress in China

  • China has made substantial progress since 2003 in strengthening surveillance and enhancing rapid response, capacity building, technical guideline development, information sharing and cooperation with animal service sectors.
  • With the support of WHO, the Pandemic Preparedness Plan developed by the Ministry of Health based on HPAI H5N1 was issued in 2005. Pandemic-related drills were conducted annually during 2006-2008. The Preparedness Plan has been recognized to have been instrumental in responding appropriately to the 2009-2010 influenza pandemic.