Bacteria that cause the bubonic plague may be more virulent than their close relatives because of a single genetic mutation, according to research published in the May issue of the journal Microbiology.
"The plague bacterium Yersinia pestis needs calcium in order to grow at body temperature. When there is no calcium available, it produces a large amount of an amino acid called aspartic acid," said Professor Brubaker from the University of Chicago, USA. "We found that this is because Y. pestis is missing an important enzyme."
Bubonic plague has killed over 200 million people during the course of history and is thus the most devastating acute infectious disease known to man. Despite this, we are still uncertain about the molecular basis of its extraordinary virulence.
"Y. pestis evolved from its ancestor Y. pseudotuberculosis within the last 20,000 years, suggesting its high lethality reflects only a few genetic changes. We discovered that a single mutation in the genome of Y. pestis means the enzyme aspartase is not produced," said Professor Brubaker.
Aspartase is present in almost all bacteria but it is curiously absent in many pathogenic types. These include mycobacteria that are pathogenic to man, Francisella tularensis and rickettsiae (both of which cause diseases transmitted to humans via insects). "This suggests that the absence of aspartase may contribute to serious disease," said Professor Brubaker.
Aspartase digests aspartic acid. Because Y. pestis doesn't have the enzyme, it produces much more aspartic acid than is required by the person infected. This may cause an imbalance to the host amino acid pools. "If this is the case then we might be able to reduce the death rates of these diseases by developing a treatment that removes some of the extra aspartic acid," said Professor Brubaker.
Comment: There is another take on what caused "Black Death", which is backed up by substantial evidence, considering serious problems with original explanations of the disease spreading rate.
From
New Light on the Black Death: The Cosmic Connection[T]he Black Death, one of the most deadly pandemics in human history, said to have killed possibly two thirds of the entire population of Europe, not to mention millions all over the planet, probably wasn't Bubonic Plague but was rather Death By Comet(s)!
Oh yeah! That's far out, isn't it?
Maybe not. Baillie has the scientific evidence to support his theory and his evidence actually supports - and is supported by - what the people of the time were saying: earthquakes, comets, rains of death and fire, corrupted atmosphere, and death on a scale that is almost unimaginable.[...]
Baillie sums up the problem as follows:
The Black Death of 1347 was believed to be the third great outbreak of bubonic plague; a plague that is traditionally spread by rats and fleas. The previous instances were the Plague of Athens in 430 BC and the plague at the time of Justinian which arrived into Constantinople in AD 542. The Plague of Athens was described by Thucydides, while the Justinian plague was described by Procopius, among others. [...]
It is generally believed that the plague hit an already weakened population in Europe. [...]
At its most basic, the problem is with those rats and fleas. For the conventional wisdom to work there have to be hosts of infected rats and they have to be moving at alarming speed - you would almost have to imagine infected rats scuttling every onward (mostly northward) delivering, as they died, loads of infected fleas. The snags with this scenario are legion. For example, there are no descriptions of dead rats lying everywhere (this is explained by suggesting that either the rats were indoors, or people were so used to dead rats that they were not worth mentioning; though if they were indoors how did they travel so fast?) It did not seem to matter whether you were a rural shepherd or cleric or a town dweller, both were infected. Yet strangely with this very infectious disease some cities across Europe were spared. Moreover, these rats must have been happy to move to cool northern areas even though bubonic plague is a disease that requires relatively warm temperatures. Then, when there are water barriers, these rats board ships to keep the momentum going. (Baillie)
Comment: There is another take on what caused "Black Death", which is backed up by substantial evidence, considering serious problems with original explanations of the disease spreading rate.
From New Light on the Black Death: The Cosmic Connection
[T]he Black Death, one of the most deadly pandemics in human history, said to have killed possibly two thirds of the entire population of Europe, not to mention millions all over the planet, probably wasn't Bubonic Plague but was rather Death By Comet(s)!
Oh yeah! That's far out, isn't it?
Maybe not. Baillie has the scientific evidence to support his theory and his evidence actually supports - and is supported by - what the people of the time were saying: earthquakes, comets, rains of death and fire, corrupted atmosphere, and death on a scale that is almost unimaginable.[...]
Baillie sums up the problem as follows: