Mexico City commuters wore face-masks on Monday, to protect against a deadly outbreak of swine flu that has killed 149 in Mexico. Cases of infection have also been confirmed in the U.S. and at least four other countries. The head of the World Health Organization has warned that the deadly disease is a "serious situation" with "pandemic potential."

In today's TNR slideshow, we review the tragic consequences of past global pandemics.

--Alexander Wolf

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