HLTB21H3 Chapter 3: Chapter 3-Six plagues of antiquity.docx
17 Mar 2012
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Document Summary
As humans changed their lifestyles their relationship with infectious diseases came to be altered. For 2 million years these human populations consisted of small groups of hunter-gatherers with limited contact with other such groups and there were no domesticated animals. Such a population structure, with little or no exposure to new sources of infection and with minimal survival and transmission parasites led to a situation where epidemic diseases were virtually non existent. It was only until human populations settled down and adopted an agricultural life, or continued a nomadic existence that depended on the husbandry of large groups of animals that conditions favoured the emergence of epidemic diseases (plagues) Urban life also enhanced the transmission of certain diseases through the air and water, by direct contact, and by vectors such as snails, mosquitoes, and flies. The diseases with antiquity were characterised by long lived transmission stages as well as those involving person to person contact.
