The Ames strain used in the 2001 mailings, which naturally occurs only in Texas, accumulated only eight mutations since its introduction from Asia, revealing itself as a recent immigrant. On the other hand, the Western North American version exhibited greater genetic diversity and diverged by 106 mutations from its nearest Old World relatives, suggesting a more ancient introduction into North America. "Our phylogeographic patterns are consistent with B. anthracis arriving with humans via the Bering Land Bridge," the researchers concluded. "Historically, an animal that died of anthrax was scavenged by people for its hair, hide, bones and even consumed as food, facilitating the dispersal of spores away from a carcass," they said. Coming from the Greek word for coal -- the disease leaves a black scab on the skin -- anthrax is at its most lethal when inhaled. Humans can also contract it by ingestion or absorption through the skin. "Keim's genetic discovery is important and absolves Christopher Columbus and the conquistadors of inadvertently introducing the deadly bacteria in newly conquered lands," Adrienne Mayor, a visiting scholar at Stanford University's Department of Classics and History of Science, told Discovery News. "But historically, anthrax has indeed traveled with invading armies and was associated in ancient literature with war hostilities." According to Mayor, who has authored the book "Greek Fire, Poison, Arrows and Scorpion Bombs," two plagues described in the Old Testament -- the fifth and sixth plagues called down by Moses on the Egyptians (about 1300 B.C.) -- and a similar plague during the legendary Trojan War (also set in about 1300 B.C.) appear to have been anthrax. Related Links: |
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