H7N9 flu ‘may pose a serious human health risk,’ scientists write

Researchers at the Chinese Center for Disease Control and Prevention in Beijing have offered details about three of at least nine known deaths associated with H7N9 bird flu.

In a report on the virus published online by the New England Journal of Medicine, the team described genetic and clinical characteristics of the new influenza strain, the first H7N9 known to infect humans. The viruses detected in the three patients all originated in birds, and contain genetic elements similar to known H7N9, H9N2, and H7N3 viruses.

The similarities between avian flus and the new virus may support the possibility that people catch the new H7N9 from birds and not from other people, the researchers wrote. At the same time, the team found changes in the H7N9 viral genes that have made past flus more virulent in people.

All of the victims in the three fatal cases described -- an 87-year-old man, a 27-year-old-man, and a 35-year-old woman -- suffered a high fever and cough, and as their disease progressed, they developed acute respiratory distress syndrome, in which fluid builds up in the air sacs of the lungs, preventing oxygen uptake in the body. The eldest H7N9 patient died after 13 days; the other two patients, after only about a week. All three received antiviral medications about a week after they fell ill.

“Severe avian influenza A [H7N9] infections, characterized by high fever and severe respiratory symptoms, may pose a serious human health risk,” the authors wrote.

Since February, the World Health Organization has reported, there have been 29 cases of H7N9 infection in China. News reports Thursday upped the number of confirmed cases to 38 and of confirmed deaths to 10.

In an editorial accompanying the New England Journal of Medicine report, U.S. Centers for Disease Control and Prevention flu researchers Dr. Timothy Uyeki and Nancy Cox said that the H7N9 “situation raises many urgent questions and global public health concerns,” arguing that the “key question for pandemic risk assessment is whether there is evidence of either limited or, more important, human-to-human transmission.”

They wrote that the discovery of the illnesses in China “is yet another reminder that we must continue to prepare for the next influenza pandemic,” and that “coming weeks” would reveal whether the H7N9 cases represented that pandemic’s beginning.

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