Science News

New flu: H10N8

Fri, 7th Feb 2014

Chris Smith

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3D Model of an influenza virus particle.A new fatal strain of flu has been identified in a patient in China.

Documented in the current episode of the Lancet medical journal, the H10N8 bird flu virus was recovered from a 73 year old woman in Nanchang, China, in November 2013.

The patient presented with a cough and fever, which began about 4 days after a trip to a poultry market where the woman had purchased a chicken.

Despite treatment with antiviral agents, and even donor antibody, the patient died from respiratory failure 9 days into her illness.

Influenza virus was grown from diagnostic samples collected from the woman during her time in hospital. The genetic sequence of the virus revealed that it was of the subtype H10N8, which has not previously been recorded in humans.

The analysis also showed that the coat proteins of the virus, comprising the H and N molecules, were from two different bird flu viruses, while the internal genes, which control how the virus grows and replicates itself, were from an H7N9 virus similar to the one found circulating in China in 2013.

These findings suggest that this new H10N8 agent represents a new  "reassortant" formed when a mixture of viruses juggle their genes, producing a hybrid.

The Nanchang City public health team, who authored the present Lancet report, speculate that the woman picked up the infection during her trip to the poultry market, although follow-up studies in the area have so far failed to identify the source.

Reassuringly, none of the people with whom the patient had contact after the onset of her illness picked up the infection, and tests show that the novel agent is sensitive to the antiviral Tamiflu.

More worryingly, the Chinese team conclude their paper by reporting a second, more recent death from H10N8 on 26th January 2014, highlighting that the new virus appears to be minimally pathogenic in poultry, which could enable it to circulate for longer before its presence is detected, and pointing out that the first fatal case of H5N1 in 1997 preceded the next 17 cases by at least 6 months...

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One of the concerns, of course, is that if the bird flu viruses can recombine from several different viruses, that eventually they'll infect someone with a co-infection of the human type flu, and recombine to form a new form of bird flu - human flu hybrid capable of propagating quicker.

I wonder if one of the problems in China is that chickens are often sold as live meat.  In the USA, the end consumer almost never gets the live chickens.  The farmers and butchers may already have an immunity to the bird flu strains, but the general public would not.

Would selling packaged meat reduce the likelihood of the bird flu jumping to humans in the near future? CliffordK, Fri, 7th Feb 2014

Maybe, but not necessarily, because the reassortment event that produces the fatal strain can occur in birds and then only limited contact with humans is needed for the infection to jump into us, assuming it's got the power to spread.

In China there are a lot of people and a lot of migratory aquatic birds, which are the natural hosts of flu and the perfect mixing pot for these reassortants to establish and evolve. chris, Mon, 10th Feb 2014

What are the symptoms of the flu in a bird?

Hacking cough?
Runny nose?
Getting nasal mucosa on one's hands and touching everything in sight?

It is quite possible that chickens are different enough from humans that a highly infectious strain capable of jumping to humans and passing from human to human could not be incubated solely in birds.  Of course the birds might be able to catch the human version of influenza, or there is the risk is that if the virus could slowly pass from human to human, in a few generations it could increase its infectious rate.

Other mammals such as pigs, cattle, goats, dogs, or cats may be more likely to generate a strain of the flu that is highly infectious to humans. 

The risk, though, is that if the avian flu rarely passes to humans, then we could be significantly lacking in immunity. CliffordK, Tue, 11th Feb 2014

I think so far the cases have been bird to human transmission. Avian flu binds to a receptor that is uncommon in the human upper repository tract but is present deeper in the lungs, which is why infection has mainly been in poultry workers. 
Epithelial cells of the pig trachea carry both the human and avian type receptor molecules, so pigs can be infected with both avian and human influenza virus strains and thus serve as a ‘mixing vessel’ for the emergence of types of influenza through reassortment. yellowcat, Fri, 4th Apr 2014

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