Yikes! Bacteria in the attack
From
Ars Technica:
Scientists pinpoint when harmless bacteria became flesh-eating monsters
Bacterial diseases cause millions of deaths every year. Most of these bacteria were benign at some point in their evolutionary past, and we don�t always understand what turned them into disease-causing pathogens. In a new study, researchers have tracked down when this switch happened in one flesh-eating bacteria. They think the knowledge might help predict future epidemics.
The flesh-eating culprit in question is called GAS, or Group A β-hemolytic streptococcus, a highly infective bacteria. Apart from causing the flesh-eating disease necrotizing fasciitis, GAS is also responsible for a range of less harmful infections. It affects more than 600 million people every year, and it causes an estimated 500,000 deaths.
These bacteria appeared to have affected humans since the 1980s. Scientists think that GAS must have evolved from a less harmful streptococcus strain. The new study, published in PNAS, reconstructs that evolutionary history.
Lead researcher James Musser of the Methodist Hospital Research Institute said, �This is the first time we have been able to pull back the curtain to reveal the mysterious processes that gives rise to a virulent pathogen.�
Some more:
Musser could also accurately date the genetic changes in GAS by using statistical models to turn back the clock on evolution. They say the last genetic change, which made GAS a highly virulent bacteria, must have occurred in 1983.
That timing makes a lot of sense. �The date we deduced coincided with numerous mentions of streptococcus epidemics in the literature,� Musser said. Since 1983, there have been several outbreaks of streptococcus infections across the world. For example, in the UK, streptococcus infections increased in number and severity between 1983 and 1985.
Biology is a strange science -- something can go along for years and then, a flip happens and the story is re-written. We see this a lot in the evolutionary record.
Posted by DaveH at April 15, 2014 3:34 PM