Protecting public health was a core function of governments long before the expansion of the state in the 20th century. “Great fears of the sickenesses here in the City, it being said that two or three houses are already shut up,” Samuel Pepys wrote in his diary on April 16, 1665. “God preserve us all." Londoners trying to flee the plague had to obtain a certificate of good health signed by the lord mayor, who also enforced a curfew and a lockdown of plague households. A generation after the Great Plague, Massachusetts was passing laws for the quarantining of smallpox patients.
Nineteenth century urban Britain experienced a huge rise in deaths from infectious diseases. In 1849, more than 50,000 people died from a cholera epidemic that swept London. The previous year, Parliament passed the landmark Public Health Act. According to historians of the act, “public health was not a party matter, nor was the need for comprehensive sanitary legislation controversial." That year, the physician John Snow made the first great epidemiological breakthrough with his discovery that fecal contamination causes cholera.