Tuesday, July 5, 2011

Hendra and other deadly viruses.

There has been much in the press recently about the outbreak of Hendra virus in Queensland which has led to the death of a number of horses and to the very real health scare for those who have treated, and handled the sick animals.

The human race has been afflicted for millenia with "plagues" which have devastated communities and then virtually "disappeared". The bubonic plague was one that killed almost half of Europe in the middle ages, and is rarely heard of these days, although it is still "out there" and still occasionally killing people. Of course there are other epidemics that crop up from time, measles, influenza and now HIV which has been with us probably since the 1920's.

As I pointed out in an earlier article, the human race has only been around for about 20,000 generations, whilst bacteria and viruses have been around for millions of generations and have had longer to learn how to adapt far more quickly than we humans have. The other thing that has happened is that within the last four generations, homo sapiens has gone from living his life in a village surrounding, to now being a globe trotter extraordinaire! That, plus the world population now being around 7 billion means that infections can now travel much farther, much quicker and in a larger population than ever before.

The final piece of the jigsaw is that we live in much closer proximity to the pool of germs that cause these infections- animals, birds etc - so it so much easier for these germs to "jump species". Measles came from animals where it is known as Rinderpest. Bubonic plague -AKA Yesenia Pestis - is spread by flea infested rats, where it is the flea that does the biting and the rats do the spreading!! Influenza comes from birds and especially the wild, migratory ducks that call China home. And of course HIV comes from Chimpanzees in Africa and spread to humans when it was used as a source of food in the last century.

But it is not just a one way street: humans gave cattle bovine TB, and in America passed leprosy onto the Armadillo which on occasion has returned the compliment, leading to sporadic outbreaks in those areas where skinning armadillos is seen to be a fun idea.

Thankfully, we have good vaccination programs to help control many of these devastating diseases, but because these organisms are quick to adapt, and because humans are so omnipresent, it is highly likely that we will face some very serious epidemics in the decades to come: you have been warned!
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