Despite being so small they can’t be seen with the naked eye, pathogens that cause human disease have greatly affected the way humans live for centuries.
Just as organisms that infect us make changes in us - we too make changes in them and they grow and adapt to their human hosts.
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Humans play host to many little passengers. Right now, you’re incubating, shedding or have already been colonised by viral, bacterial, parasitic or fungal microorganisms - perhaps even all of them.
It’s the ability of our immune system to remember past infections, and pass this memory on to our kids, that allows us to survive infectious diseases.
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