Death toll rises to 36 in H7N9 outbreak

May 15, 2013 (CIDRAP News) – The first patient in China's Hunan province with confirmed H7N9 influenza has died, lifting the outbreak's fatality count to 36, according to official and media reports today.

The patient is a 64-year-old woman who died yesterday morning at a hospital in Shaoyang, about 20 days after her illness was detected, according to a report from Xinhua, China's state news agency. The source of the information is the Hunan Provincial Health and Family Planning Commission.

The number of new H7N9 infections has tailed off in recent week, with the latest one reported May 7, which edged the number of cases to 131. However, the death toll continues to rise, because many of the previously confirmed patients are still hospitalized, battling the often serious complications of the disease, which can include acute respiratory distress syndrome and organ failure.

It's not clear why the outbreak has stalled. Influenza experts suspect closures of live-poultry markets could be curbing infections in humans, or the virus could be showing a drop in warm weather months seen with other avian influenza viruses. Another possibility is that H7N9 could be dying out, a pattern that has been seen before with other novel flu viruses.

In other developments, a veterinary epidemiologist from Scotland yesterday raised the possibility that H7N9 could emerge and circulate in the poultry trade without a link to commercial farms. Nick Honhold, BVSc, MSc, PhD, a consultant based in Edinburgh, detailed his suggestion in a post on ProMED Mail, the online reporting system of the International Society for Infectious Diseases.

Despite extensive testing by Chinese animal health authorities, the virus has not been detected on poultry farms and has mainly been found in a fairly small number of poultry wholesalers and live-poultry markets. The lack of poultry farm findings has been one of the puzzling aspects of the H7N9 outbreak.

Honhold wrote that the poultry market and trading system in China is varied and complex and more testing is needed to determine the proportions of people who had contact with poultry markets who did and didn't get sick. He added, however, that the lack of another common source suggests that live-poultry markets must somehow be involved.

He questioned if movements of birds, equipment, and people between the markets could spread and maintain the disease. Also, he wrote that more details are needed about the farms that have been tested for the virus, such as whether they're backyard units or facilities that are supplying the markets.

An understanding of China's poultry market system is essential to understanding how the virus could be spreading, he wrote. China's system might resemble that of other countries in which collection points aggregate birds from several sources before smaller shipments make their way to live markets.

See also:

May 15 Xinhua story

May 14 ProMED Mail post

Newsletter Sign-up

Get news & practices.

Sign up now»

OUR UNDERWRITERS

Unrestricted financial support provided by

Bentson Foundation 3M United Health Foundation Gilead Become an underwriter»