The actual term Expiration Date refers to the last date a food should be eaten or used. Last means last -- proceed at your own risk. Other, more commonly spotted terms are:  1 Sell by date. 2  The labeling sell by tells the store how long to display the product for sale. 3  You should buy the product before the date expires. 4  This is basically a guide for the retailer, so the store knows when to pull the item.
When an animal or person is infected with Yersinia pestis, the bacteria affect the lymph system, causing the characteristic symptoms. If bubonic plague is left untreated, plague bacteria can quickly multiply in the bloodstream, causing septicemic plague. The bacteria could also progress to the lungs, causing pneumonic plague.
Bubonic plague is fatal (though there is now a cure) and leads to an infection of the lymph nodes, which become swollen (bubo is Latin for bump). Here's what actually happens. The bacteria grow inside the flea, causing conditions which block the insect's stomach and induce extreme hunger. The flea starts to feed on a host, and in this way the disease spreads. Boccaccio, Plutarch and Chaucer all mention the Black Death in their literary works. The disease made short life spans even shorter.