summer vacation

I wasn't able to take any time off from work this summer and with autumn only a few days away it's good to step back and see if anything else was busy all summer long.

Lo and behold, the nasty ole flu virus was equally as industrious. You see, influenza is active all year round in the tropics but here in the temperate regions the flu is seasonal, coming on strong every winter then disappearing in the late spring.

There's a story on the Penn State website that relates to this dilemma, titled Flu virus trots globe during off season. Catchy title, huh?

Here's an excerpt from that article:

Flu infections in the Northern Hemisphere typically follow a familiar pattern. Some time before the start of the winter infection season, the virus evolves, changing enough to evade the previously primed immune system. Then, just before summer, the virus disappears, only to resurface the next fall with a completely different genetic makeup, ready to fool the immune system anew.

But little is known about what happens to the virus between two successive winters, or how and where it is able to sustain itself.

The key question, Edward Holmes, professor of biology at Penn State, explains is whether the virus settles into a dormant state waiting for the right cues of temperature and sunlight to reactivate, or whether it migrates to viral reservoirs in the tropics, from where it is later reintroduced.

It is thought that places in Southeast Asia, where humans and animals live in close proximity, might be the permanent melting pot where viruses continually circulate and exchange genetic information.

"If the viruses had been dormant, samples from successive seasons in each region would only be closely related to other viruses of that same region," said Holmes, who is also affiliated with Penn State's Center for Infectious Disease Dynamics (CIDD). "The fact that they are, instead, interspersed clearly tells us that the viruses are seasonally migrating across both hemispheres."

However, it is still fully unclear where and when the viruses are evolving to beat the immune system. According to Nelson, the virus changes its entire genetic makeup somewhere during the summer off-season, and it likely does this in the tropics, where the virus is found year-round.

Given how much influenza has affected past and current human health, it's amazing how much we don't know about it. Back in 1918-1919 an estimated 50 - 100 million people died as a result of subtype H1N1 of Influenza A, Avian Flu has similar potential for large scale causalities. In the grand scheme of things, the money spent on Homeland Security to protect us from agents that might kill a dozen people here, maybe a hundred there just seems wasted. Not even getting into the fact that the Homeland Security money is as likely to be spent on a parade in a small town as something that might actually protect people--it just seems that biological threats, natural and man made, are a much more serious danger.

Oh well, I'm just having some dour thoughts today, I guess.

Comments

tiff said…
They're aliens, I'm convinced of it.
GA Girl said…
For not having brains, the little buggers are pretty smart. I know, I know - not brains, natural selection. Autumn is a melancholy time and my favorite time of year LOL
SassyAssy said…
ya'know your science posts are not my favorite, but this one was pretty damn interesting!

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