What was the reason the black death started

The bacterium Yersinia pestis, which results in several forms of plague, is believed to have been the cause. The plague created a series of religious, social and economic upheavals, which had profound effects on the course of European history.

racism and segregation.

its main object was the establishment of "settlement houses" in poor urban areas, in which volunteer middle-class "settlement workers" would live, hoping to share knowledge and culture with, and alleviate the poverty of, their low-income neighbors.