Just last year China was dealing with the new H7N9 bird flu that had just jumped from birds to humans. Now, there's another new strain of bird flu that is capable of infecting humans.
The new flu is caused by the influenza virus H6N1, which infected a 20-year-old Taiwanese woman in May. She was hospitalized for her high fever, cough, and shortness of breath. She was treated with anti-viral medication and recovered.
Though the patient survived her infection, the doctors were mystified by her illness — she was negative for all normal respiratory illnesses. They kept looking and eventually discovered that she was infected with a common bird flu virus that has never before been seen in humans.
The find was published in the Nov. 14 issue of the journal The Lancet Respiratory Medicine.
The numbers and letters that designate flu strains — H for hemagglutinin and N for Neuraminidase — are two different proteins on the outside of the virus that are slightly different in different strains. They determine what animals the virus can infect — the H protein works as a lock-and-key with proteins on the outside of our cells to let the virus in.
adapted from wikipedia
These proteins usually mean that a virus can only successfully infect some animals — they are tailored to their hosts. But the genes that make these proteins can change and adapt and evolve to infect more than just a handful of species.
That's exactly what seems to have happened in this case. The human-infecting version of H6N1 had a mutation in the virus that enabled it to bind to our lung cells, according to the researchers. The researchers said that this mutation is widespread in the general virus population in chickens.
"Our findings suggest that a unique group of H6N1 viruses with [this mutation] have become endemic and predominant in poultry in Taiwan. As these viruses continue to evolve and accumulate changes, they increase the potential risk of human infection," the authors write in the paper.
What's interesting is that this patient didn't have direct contact with live birds, the normal route through which bird viruses jump to humans.
We don't know yet how dangerous this newly human-adapted bird flu is or will be. Right now, the situation seems like an isolated infection, according to LiveScience:
So far, there's no evidence that H6N1 can spread between people. Of the 125 cases of flu reported in Taiwan since the woman became ill, none were caused by H6N1. The researchers also tracked down 36 people who came into contact with the woman, six of whom became sick around the time she did, but there was no indication they had H6N1.
The woman's friends who became sick were only tested for presence of the virus, though, several days after they were feeling sick. They could have had it and already cleared it from their systems. No other humans hospitalized with flu-like symptoms tested positive for the virus.
While one Taiwanese woman getting sick doesn't seem like something to worry about, we never know when one of these human jumps could be the start of a larger outbreak. When a new virus infects humans it can be a big deal, even if it isn't too deadly. That's because our immune systems have no experience against these viruses (unlike the seasonal flu viruses that circulate yearly).
Marion Koopmans, a virologist in the Netherlands wrote in a comment in same issue of The Lancet that, "although the total number of recognized human cases is less than 1000 worldwide, each person infected with an animal influenza virus is judged a threat to public health, because the influenza pandemics of the past 100 years have all emerged from animals."
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