CALIFORNIA’S FIRST CHINESE IMMIGRANTS ARRIVED at a tumultuous time. From the 1860s to the early 1900s, a raft of epidemics, from smallpox to cholera, ravaged the San Francisco Bay Area, and especially Chinatown. Lacking scientific research on disease transmission, local health officials often blamed outbreaks on living conditions in Chinatown and the vices of its inhabitants. In 1877, the surgeon Hugh Toland told a congressional committee that Chinese sex workers caused 90 percent of syphilis cases in the city.