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What is the new Hong Kong flu?
What is the new Hong Kong flu?
If you’ve read the headlines in the past couple of days, you’ve probably seen the death toll rise in Hong Kong, due to a mysterious new bird flu.
It seems that we’ve heard this story before; remember H1N1? The swine flu? This was the flu virus responsible for two pandemics, in 1918, and then again in 2009.
In January of 1918, a doctor in Haskell County, Kansas observed in a number of patients what seemed to him to be common symptoms of the seasonal flu, although they were unusually extreme. He’d seen influenza often, but never like this! This flu swept through the body in a violent fashion, more often than not, leaving its victims battling for their life, and losing. By March of that year, over 100 soldiers, fighting for their country in World War I, were in the hospital.
This unusually deadly flu infected 500 million people across the world, qualifying as a pandemic. It killed nearly 5% of the world’s population at the time, making it one of the deadliest natural disasters in human history, according to Wikipedia’s article on the 1918 flu pandemic. The pandemic soon acquired the nickname, Spanish flu, due to the perception that Spain was hardest hit, though this was apparently a false impression.
This flu virus was unique; it killed by causing the immune system to “overreact”, in a sense.
Normally, cells of the immune system communicate to one another through small molecules called cytokines. These are used to instruct neighboring cells as to the type of pathogen present, and the type of response necessary. The H1N1 virus, so named, by the way due to the two proteins, hemagglutinin and neuraminidase, on the virus’ surface, essentially caused a fatal reaction in which immune cells received positive feedback after releasing cytokines, and continued to produce the molecules.
Too much of a good and necessary thing, can be fatal, in this case.
The reason for the flu pandemic of 1918? World War I contributed, to be sure. The soldiers lived in close quarters for extended periods of time, and traveled across people groups, hastening the spread of the disease. There is speculation that the soldier’s immune systems were weak with malnourishment and stress, rendering them more susceptible.
But what caused the reemergence of this strain in 2009?
The answer to this question is less clear; the first outbreak was detected in Mexico City, with signs that an epidemic had been present there, without being recognized as such. The CDC identified two cases in San Diego in April, 2009, and confirmed the first death in Houston Texas; a toddler from Mexico City.
The pandemic of 2009 is not quite as well documented as that of 1918, since scientists are still working to trace the epidemiology.
Contrary to popular belief, the “swine flu” is called such because it resulted from a reassortment of bird, swine, and human flu viruses, combined with a Eurasian pig flu virus.
Well, what about this new flu, the one emerging in Hong Kong? Will this too, become a pandemic?
It’s probably too early to tell.
However, the H7N9 avian influenza virus is causing quite a panic in China. The World Health Organization first reported three human infections with this new strain on April 1, 2013, and the number has multiplied since then (nearly 30, as of Tuesday, April 9th).
The H7N9 virus is an avian flu, novel in both birds and humans. The WHO says that avian flu viruses are unlikely to infect humans; only after exposure to infected poultry.
So, unlike the swine flu, the “bird flu” is somewhat justified in its name…
Are there any treatments that work on this strain?
As a matter of fact, yes. The virus seems to be susceptible to the influenza antiviral drugs oseltamivir and zanamivir, though the CDC states that this is an evolving situation and there is still much to learn.
As far as we know, no cases outside of China have been reported, and no cases have found to be the result of person-to-person transmission. However, if there’s one thing I know about viruses, especially influenza, it’s that they constantly change, and could gain this ability.
And indeed, it is the ability of the virus to spread among humans that will determine the key to controlling the number of H7N9 patients.
Check out this eerie update!