The current Ebola virus outbreak, which is the largest ever
reported, has overwhelmed struggling health systems in some of the
world's poorest countries. Past outbreaks have been brought under
control fairly rapidly once the virus was identified and protective
measures put in place. The virus is spread between humans through direct
contact with infected bodily fluids. There is no cure for Ebola, but
with intensive care treatment and proper hydration, patients have a
chance of survival. But what about people who come into contact with the
virus and do not get infected? Could something in their genes keep
their body immune?
The Black Death, one of the most infamous plagues in history, arrived in Europe through the Sicilian port of Messina in October, 1347. Twelve trading ships of Genoese origin arrived during that month with crews that were either dead or covered with black boils. Sicilian authorities ordered the ships out of the harbor and even set some aflame with burning arrows. Unfortunately, the Black Death had already established a foothold and killed nearly a third of all Europeans, over 20 million people, before running its course over the next five years.
As horrible as it was, the Black Death spared many. A small percentage of the population became ill and recovered, and an even smaller percentage were exposed without ever becoming ill. This is where genetics may have come into play.
In the areas hardest hit by the plague, survivors married survivors. Plague survivors greatly outnumbered people who had not been exposed to the plague at all. Children in these regions carried the genes of plague survivors. In regions that were not devastated by the plague, this heredity was far less likely.
Presumably, a percentage of today's population has a gene that has been passed down through generations from couples who were both immune to the Black Death during the fourteenth century. Scientists believe this is the case, and they also believe they have discovered the gene in question.
Scientists recently discovered that some individuals do not become infected with HIV even when repeatedly exposed. Through genomic testing of these individuals, a mutation in the CCR-5 receptor gene has been discovered that may inhibit the HIV virus' entry into white blood cells. It appears that people with two copies of the mutated CCR-5 gene - one from the mother and one from the father - do not become infected with HIV when exposed. People with a single copy of the mutated gene, from either the mother or the father, become infected but appear to progress to AIDS at a slower rate than patients without the mutated gene.
This resistance or immunity is distributed globally in a rather unique pattern. It is far more prevalent in populations from Northern Europe than in populations from Southern Europe and it is almost unheard of in African, Asian, and Native American populations.
Curiously, there appears to be a correlation between regions devastated by the Black Plague and regions with populations exhibiting the highest incidence of the CCR-5 receptor mutation. Scientists believe that selection for the mutated gene coincides with populations who survived the plague.
Scientists are currently trying to verify this theory by attempting to infect cells identified as HIV-resistant with the bacteria that cause the plague. If these cells prove to be resistant to the plague bacteria, then the evidence will strongly suggest that the mutated CCR-5 receptor played a key role in surviving the Black Death in the Middle Ages.
The Black Death, one of the most infamous plagues in history, arrived in Europe through the Sicilian port of Messina in October, 1347. Twelve trading ships of Genoese origin arrived during that month with crews that were either dead or covered with black boils. Sicilian authorities ordered the ships out of the harbor and even set some aflame with burning arrows. Unfortunately, the Black Death had already established a foothold and killed nearly a third of all Europeans, over 20 million people, before running its course over the next five years.
As horrible as it was, the Black Death spared many. A small percentage of the population became ill and recovered, and an even smaller percentage were exposed without ever becoming ill. This is where genetics may have come into play.
In the areas hardest hit by the plague, survivors married survivors. Plague survivors greatly outnumbered people who had not been exposed to the plague at all. Children in these regions carried the genes of plague survivors. In regions that were not devastated by the plague, this heredity was far less likely.
Presumably, a percentage of today's population has a gene that has been passed down through generations from couples who were both immune to the Black Death during the fourteenth century. Scientists believe this is the case, and they also believe they have discovered the gene in question.
Scientists recently discovered that some individuals do not become infected with HIV even when repeatedly exposed. Through genomic testing of these individuals, a mutation in the CCR-5 receptor gene has been discovered that may inhibit the HIV virus' entry into white blood cells. It appears that people with two copies of the mutated CCR-5 gene - one from the mother and one from the father - do not become infected with HIV when exposed. People with a single copy of the mutated gene, from either the mother or the father, become infected but appear to progress to AIDS at a slower rate than patients without the mutated gene.
This resistance or immunity is distributed globally in a rather unique pattern. It is far more prevalent in populations from Northern Europe than in populations from Southern Europe and it is almost unheard of in African, Asian, and Native American populations.
Curiously, there appears to be a correlation between regions devastated by the Black Plague and regions with populations exhibiting the highest incidence of the CCR-5 receptor mutation. Scientists believe that selection for the mutated gene coincides with populations who survived the plague.
Scientists are currently trying to verify this theory by attempting to infect cells identified as HIV-resistant with the bacteria that cause the plague. If these cells prove to be resistant to the plague bacteria, then the evidence will strongly suggest that the mutated CCR-5 receptor played a key role in surviving the Black Death in the Middle Ages.
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