Medicine: Furry Dangers

Two ancient scourges — typhus and plague — spread by small, furry, bugridden animals, have invaded the U.S., taken on new character and settled down to stay. Both were recently reported to have become more deeply intrenched than epidemiologists had realized.

Blood Will Tell. Typhus in the Old World is primarily a human disease spread via lice among the unwashed. European immigrants to the U.S. once shared their lice with rats (authorities believe), and the infection began spreading through the U.S. rat population, whose fleas can reinfect human beings with a mild form of...