In 1854, an outbreak of cholera in Chicago took the lives of 5.5 percent of the population (about 3,500 people). Providence, Rhode Island suffered an outbreak so widespread that for the next thirty years, 1854 was known there as "The Year of Cholera." In 1853–1854, London's epidemic claimed 10,739 lives. The 1854 Broad Street Cholera outbreak in London ended after the physician John Snow identified a neighborhood Broad Street pump as contaminated and convinced officials to remove its handle to prevent people from drawing water there. His study proved contaminated water was the main agent spreading cholera, although he did not identify the contaminant. It would take many years for this message to be believed and fully acted upon. In Spain, over 236,000 died of cholera in the epidemic of 1854–1855. The disease reached South America in 1854 and 1855, with victims in Venezuela and Brazil. During the third pandemic, residents of Tunisia, which had not been affected by the two previous pandemics, thought Europeans had brought the disease. They blamed their sanitation practices. Some United States scientists began to believe that cholera was somehow associated with African Americans, as the disease was prevalent in the South in areas of black populations. Current researchers note their populations were underserved in terms of sanitation infrastructure and health care, and they lived near the waterways by which travelers and ships carried the disease.