Urgent search for flu source

[SidDithers]

http://www.nature.com/news/urgent-search-for-flu-source-1.12762

Researchers suspect H7N9 virus is in bird markets as human cases rise rapidly.

Virologists know its name: H7N9. What they don’t yet know is whether this novel avian influenza virus — first reported in humans in China less than two weeks ago — will rapidly fizzle out, become established in animal hosts to fuel future human outbreaks, or morph into a virus that can spread easily between people and spark a deadly pandemic.

In a frantic effort to find answers, scientists are bearing down on H7N9 on multiple fronts. They are testing wild birds and thousands of domestic fowl; analysing the viruses they find; and trying to trace people who have been exposed to infected patients. Chinese health authorities say that they have 400 laboratories looking for genetic changes in the virus.

“We are going to be sitting with bated breath over the next month to find out what happens,” says Michael Osterholm, who heads the University of Minnesota’s Center for Infectious Disease Research and Policy in Minneapolis. As Nature went to press, 24 human cases, including 8 deaths, had been reported in 11 cities, some a few hundred kilometres apart, in eastern China (see map). So many cases in such a short time over such a wide area — up from three cases in two cities a week ago — is “a very concerning situation”, says Osterholm.

Scientists urgently want to find out which sources are stoking the human infections that result in flu-like symptoms and, in most reported cases, severe pneumonia. So far, investigations of the cases remain largely inconclusive: some patients had contact with poultry or other animals just before falling ill, whereas others had not. Late last week, the H7N9 virus was found in chickens, pigeons and ducks in live bird markets in Shanghai and Hangzhou — making markets the leading suspected source. Authorities have since culled tens of thousands of birds and closed down markets in Shanghai, Nanjing and Hangzhou.

Not something to freak out over. But something to be aware of.

Sid

[Warpy]

1. Lower respiratory flu generally doesn't spread person to person

unless they are confined together in small spaces over long periods of time because the fine droplets are not effectively coughed out into the air. The infection tends to consolidate in the lower and outer part of the lung and doesn't move well up the respiratory tree. The spread from bird to human is more efficient.

The upper respiratory influenzas like H1N5 are of more concern. They spread easily through droplets in the air and the virulence is such that they cause cytokine storms, killing younger and relatively healthy people instead of targeting the very old and very young like ordinary flu strains.

The 1918 pandemic was an upper respiratory flu of extreme virulence. The death toll, disproportionately of adults in their prime, was enough to lower life expectancy by 10 years in the US that year.

China is doing the right thing, closing poultry markets and culling sick birds.