Lecture one: the history of immunology the black plague. thought to be spread by trade routes; worsened by migrations. rats had fleas, fleas carried the yersinia pestis bacteria that caused the plague (cats were seen as evil, which didn"t help because you needed cats to get rid of the rats) ::farmers were hit, they cut off food supplies causing starvation. ::peasants were taxed more leading to the peasant revolt in 1371. survivors had an immunological advantage maybe beneficial mutations. the survivors also benefitted from greater resources leading to the renaissance. ::renaissance could also be attributed to the disillusionment of the church or the collapse of feudalism. *immunity: the quality or state of being immune; a condition of being able to resist a particular disease; that which confers protection against disease. ::first seen in 2000 bc: the babylon epic of gilgamesh had accounts of pestilence and disease. *variolation: inoculating someone with the virus of smallpox to induce the disease.