Mar 23, 2019 | Updated: 12:48 PM EDT

In the Wake of Ebola—H7N9 Influenza Has Spread in Secret

Mar 13, 2015 02:39 PM EDT


In the wake of the Ebola pandemic, researchers in China have identified a virus capable of global infection that has been mutating and brewing on the sidelines. A strain of the avian influenza, the H7N9 flu emerged in eastern China in Feb. 2013 in a small population with a mortality rate of roughly 33%. But over the last year, since it reemerged in October 2013, the virus has been spreading steadily, and mutating along the way. Now public health officials fear that the growing viral infection may soon reach the levels much like the Ebola outbreak, and it is something that researchers are heavily investigating.

According to a new study published this week in the journal Nature, researchers and health officials with the World Health Organization say that since its origination in 2013 the virus has continued to infect over 400% of the original population, and has revealed a mortality rate much greater than previously thought (with nearly 50% of all patients dying of complications). And while all but three cases were in China, Hong Kong and Taiwan, public health officials fear that the disease will continue to spread far beyond the close borders of the once unified nation.

"H7N9 viruses should be considered as a major candidate to emerge as a pandemic strain in humans" the researchers said in their study.

Much like the H5N1 avian influenza that spread widely nearly a decade ago, the influenza virus remains highly contagious as the proteins and combinations of genes are entirely new to humans-which means that we have no immunity towards the viral strain.

As the virus primarily finds its hosts in the live-poultry markets of China, the researchers sequenced the entire genomes of patients associated with the infection and over 400 samples of H7N9 found in local poultry markets. While the research largely confirmed exactly what the researchers believed about avian strains of the influenza, the data also revealed that the current virus may have descended from three viruses originating in the Yangtze River delta, Jiangxi and in Guangdong (though this strain is responsible for the most cases of human infections.

New data reveals that this second wave of H7N9 influenza viruses represents a "major increase in genetic diversity" and has allowed the virus to mutate faster than researchers initially anticipated. Unless live poultry markets stop altogether, with the massive closings coinciding with an embargo on the transport of chickens, the virus is likely to persist.

To date most patients have been infected by handling chickens with the virus, and human to human infection has remained fairly limited. But as long as the chickens persist and continue to move, the health officials anticipate that the virus will too.

"It is probable that the H7N9 virus is now present across most of China" the researchers say. "Given the current pattern of dissemination, it will only be a matter of time before poultry movement spreads this virus beyond China, by cross-border trade."

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