There are cases of the plague every year. From CDC.gov: [quote]Plague was first introduced into the United States in 1900. Between 1900 and 2010, 999 confirmed or probable human plague cases occurred in the United States. Over 80% of United States plague cases have been the bubonic form. In recent decades, an average of 7 human plague cases are reported each year (range: 1-17 cases per year). Plague has occurred in people of all ages (infants up to age 96), though 50% of cases occur in people ages 12–45. Worldwide, between 1,000 and 2,000 cases each year are reported to the World Health Organization(WHO), though the true number is likely much higher. [/quote]