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H7N9 Found in Taiwan

Image of rooster in cage
Amesh A. Adalja, MD, FACP
Date posted:
April 24, 2013
Publication type:

Our Perspective on H7N9 Influenza in China: April 24, 2013

More in this series:

April 12 • April 15 • April 18 • May 6



As the ongoing outbreak of H7N9 evolves, tracking the virus’ movement outside of China will be an important method for gauging its ability to spread among birds and humans. Such spread may trigger specific actions and declarations by governments and the World Health Organization (WHO). Until today, there was no confirmed presence of the virus outside of China’s borders.

Case Update

As of today, Taiwan became the first location outside of China to report a human case of H7N9. This brings the total number of confirmed human infections to 109, with 22 deaths.1

The case in Taiwan is a 53-year male who traveled in Suzhou, a city in the Jiangsu province of China. He became ill 3 days after his return and was hospitalized on April 9. The patient does not recall any contact with poultry.

As more information on case patients is revealed, the epidemiology and patterns of illness may help us understand both the true severity of the infection and the risk factors for a severe course of illness. New data from Hong Kong University and the WHO reveal that half of the serious cases have occurred in people older than 60 years, and deaths have been more common in elderly men.2,3

Poultry Market Closed

The live poultry market in Shanghai was closed on April 6, resulting in what has been described as a “dramatic slowdown” in cases. Ducks, pigeons, and chickens in the poultry markets were found to harbor the virus. No migratory birds have yet tested positive for H7N9.4

Significance and Implications

The discovery of a case outside of China is an important development, as it illustrates the ability of emerging viruses to exploit patterns of travel. That Taiwan, a nation highly concerned about and prepared for the importation of infectious disease threats, was the first to report a travel-related case is not surprising given its proximity and business ties to China’s mainland.

The lack of exposure to poultry in the Taiwanese patient is further evidence that limited human-to-human spread of H7 influenza likely occurs. In the coming days, assessing the genetic makeup of the virus will be important to efforts to quantify the ability of this virus to spread in humans.

As many patients, including the Taiwanese man, were likely infected in early April, before the Shanghai live poultry market—the presumed epicenter of the outbreak—was closed, studying the time pattern of infection may reveal what proportion of the cases are being spread through human-to-human transmission vs. known (or unrecalled) poultry exposure.  

The older age of people who have become ill highlights the interaction that may occur between an infectious disease and the person who becomes infected. Disproportionate numbers of infections in people who are older may indicate that, like seasonal influenza, the H7N9 virus may exploit age-related immune system deterioration or interact with other medical conditions, such as cardiovascular disease, chronic liver disease caused by hepatitis B virus, or diabetes mellitus. Untangling these relationships and associations will help inform the disease control plans and actions taken by China’s government and individual hospitals.


  1. Taiwan man contracts H7N9 bird flu, first outside mainland China. Reuters. April 24, 2013. Accessed April 24, 2013.

  2. Arima Y, Zu R, Murhekar M, et al. Human infections with avian influenza A(H7N9) virus in China: preliminary assessments of the age and sex distribution. Western Pacific Surveillance and Response Journal. 2013;4(2). Accessed April 24, 2013.

  3. WHO ponders preponderance of older men with H7N9. CIDRAP News. Accessed April 24, 2013.

  4. WHO: H7N9 virus ‘one of the most lethal so far.’ CNN. Accessed April 24, 2013.



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