"Seven Billion World Population in Six Years From Now. The world population is predicted to reach the seven billion mark on Oct 18, 2012. World population hit the six billion mark in June 1999, over 3.5 times the population at the beginning of the 20th century and roughly double its size in 1960. The time for the global population to grow from 5 billion to 6 billion, a dozen years, was shorter than the interval between any of the previous billions. The population today is nearly four times the number in 1900. Behind that increase is a vast gulf in birth and death rates around the world." - World Health Organization, (2006)NATURAL POPULATION CONTROL
"The 1918 influenza virus that killed more than 20 million people worldwide originated from American pigs and is unlike any other known flu bug, say researchers. They warn that it could strike again. Using lung tissue taken at autopsy 79 years ago from an Army private killed by the flu, scientists at the Armed Forces Institute of Pathology made a genetic analysis of the virus and concluded it is unique, though closely related to the SWINE FLU.
“This is the first time that anyone has gotten a look at this virus which killed millions of people in one year, making it the worst infectious disease episode ever,” said Dr. Jeffery K. Taubenberger, leader of the Armed Forces Institute team. “It does not match any virus that has been found since.”
Although the disease that caused the worldwide epidemic was called. Spanish Flu, “the virus apparently is a mutation that evolved in American pigs and was spread around the globe by U.S. troops mobilized for World War I,” said Taubenberger.
The Army private whose tissue was analyzed contracted the flu at Fort Jackson, S. C. For that reason, Taubenberger and his colleagues suggest in the journal Science that the virus be known as Influenza A/South Carolina. Army doctors in 1918 conducted autopsies on some of the 43,000 servicemen killed by the flu and preserved some specimens in formaldehyde and wax. Taubenberger said his team sorted through 30 specimens before finding enough virus in the private's lung tissue to partially sequence the genes for hemagglutinin and neuraminidase, two key proteins in flu virus.
“The hemagglutinin gene matches closest to swine influenza viruses, showing that this virus came into humans from pigs, “said Taubenberger. The finding supports a widespread theory that flu viruses from swine are the most virulent for humans. Most experts believe that flu viruses reside harmlessly in birds, where they are genetically stable. Occasionally, a virus from birds will infect pigs. "The swine immune system attacks the virus, forcing it to change genetically to survive. The result is a new virus. When this new bug is spread to humans, it can be devastating."
MUTATIONS
Two other flu viruses spread all over the world since 1918 - Asian flu in 1957 and the Hong Kong flu in 1968 - and both mutated in pigs.
Robert Webster, a virologist and flu specialist at St. Jude Children's Research Hospital in Memphis, said the study is important because “eventually we will have another influenza pandemic.'' Knowing what the 1918 virus was like may help researchers learn why it was so deadly and virulent, he said. “Now we are in a better position to combat it,'' he said. ``If it comes back, we can design a vaccine based on that genetic sequence.''
Webster said the study supports the idea that health authorities should monitor viruses in pigs worldwide to develop an early-warning system of mutating flu bugs that could plague humans. Currently, flu infections are monitored in humans only, he said, and flu vaccines are redesigned annually to be effective against the most common strain of the virus found in humans.
Taubenberger said few people appreciate just how devastating the 1918 flu pandemic was. "It killed 21 million people worldwide in less than a year, Some analysts suggest it could have been 40 to 50 million.'' In the United States, about a quarter of the population had the flu and 2 percent to 3 percent died - some 700,000 people. The Asian flu and Hong Kong flu pandemics were much milder and had a death rate of less than 0.1 percent.
Taubenberger said many of the thousands of young men crammed onto World War I troop ships were just developing the flu as they left the United States. "After a week's crossing, the ships would arrive in France with hundreds of sick servicemen. Many would die. There were horrible casualties on those troop ships.''
It's kind of counter-intuitive sometimes, that an agent that -- an infectious agent that is very good at killing its host is actually not a very well adapted infectious agent. That is, that bacteria that live on your skin or inside your colon are extremely adapted to living in humans. They don't cause disease. And so they have a nice relationship. They have set up shop and they live happily on your skin and you don't do anything about it, and occasionally there's even a mutually beneficial relationship that occurs. For example, some of the vitamin in your colon make a vitamin, vitamin K that we need.
In the case of bacteria or viruses that are not so well adapted, if they kill their host very quickly, they actually may limit their own ability to spread to other people. That is, if they kill people so quickly that they don't have time to replicate, they're kind of hurting their own chances of replication.
In this case, it was something in between. It was a virus that certainly killed a lot of people, but realistically only killed a small percentage, 2 to 5 percent of the people that were infected. So it was clearly a really good virus to infect humans. It spread amazingly well from person to person and spread all over the world. But probably in about a year's time, from 1918-19, practically every person on earth was at least exposed to this virus. So everyone formed an immune response against the virus in one degree or another. So that would put enormous pressure on the virus to mutate, to change its coat so that it could continue to infect humans.
Possibly what happened was that whatever caused this virus to be so unbelievably virulent changed when the virus mutated and the viruses that continued to circulate both in humans and in pigs after 1918 are probably actually mutated descendants of the virus but not the 1918 virus itself.
- Associated Press (Researchers Solve Genetic Puzzle of 1918 Influenza Pandemic,” 3.21.1997. Image: "Excess Mortality in US Cities During Influenza Epidemic": Dying Population Chart, 1919).
VIOLETPLANET SAYS: Breeding without limitation = Swine.
No comments:
Post a Comment