Avian Flu Scan for Sep 19, 2013

Cambodian H5N1 cases
H7N9 evolution clues

Two Cambodian girls contract H5N1, one dies

Two young Cambodian girls have contracted H5N1 avian flu, one fatally, bringing the country's case total this year to 20, according to a report today from Xinhua, China's state news agency.

A 2-year-old girl from Kampot province died yesterday in a Phnom Penh hospital. The deputy director of Kantha Bopha Children's Hospital said, "The little girl from Kampot was in very serious condition when she arrived at our hospital."

The second girl, age 5, is from Takeo province. She is in stable condition in Kantha Bopha hospital. The Xinhua story did not specify when the girls got sick or whether they had contact with sick or dead poultry.

Of the 20 Cambodian H5N1 cases so far this year, 11 have been fatal, and the disease has hit children especially hard since it was first detected in the country in 2005. Since then, Cambodia has confirmed 41 H5N1 cases and 30 deaths.
Sep 19 Xinhua article


H7N9 gene study hints at two reassortant events

A detailed genetic analysis exploring how the new H7N9 flu virus evolved in China found that it took at least two reassortant steps involving distinct H9N2 viruses from different hosts to generate the virus. The study, conducted by a research team from China, appeared today in Cell Host & Microbe.

The group based its observations on whole-gene sequencing and phylogenetic analysis of 45 H7N9 and 42 H9N2 viruses from humans, poultry, and wild birds. Analysis revealed that the first reassortant, which produced an early version of the virus in wild birds, likely occurred between an H9N2 virus and other Eurasian avian influenza strains that contained H7 or N9 components.

Because of difficulty obtaining viral isolates from wild birds, scientists haven't been able to precisely determine the source of H7N9 hemagglutinin and neuraminidase (the "H" and "N" components, respectively). They wrote, though, that, considering surveillance data from humans and birds, the components likely came from wild birds.

The second reassortant probably came from an H9N2 in Chinese domestic birds and an earlier H7N9 strain that had spread from wild birds to domestic ones.

The researchers estimated that the second reassortment likely occurred in early 2012 and that the events, plus gene mutations and minor reassortant events, might help explain the diverse genotype seen in China's new H7N9 viruses.

The findings reinforce the important role wild birds play in the emergence of new flu viruses and the need to include many data sources for effective flu surveillance, the team concluded.
Sep 19 Cell Host Microbe abstract

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