A major epidemic occurred in Ireland between 1816 and 1819, during the famine caused by a worldwide reduction in temperature known as the Year Without a Summer. An estimated 100,000 people perished. Typhus appeared again in the late 1830s, and yet another major typhus epidemic occurred during the Great Irish Famine between 1846 and 1849. The Irish typhus spread to England, where it was sometimes called "Irish fever" and was noted for its virulence. It killed people of all social classes, as lice were endemic and inescapable, but it hit particularly hard in the lower or "unwashed" social strata.