REPORTED CASES OF HUMAN PLAGUE INFECTIONS IN THE UNITED-STATES, 1970-1991

From 1970 to 1991, 295 indigenous cases and one imported case of human plague were reported in the United States. Eighty-two percent of the total indigenous cases occurred in New Mexico, Arizona, and Colorado. Ninety-three percent of these cases had onset in the months of April t hrough November. Most cases (89%) presented as bubonic or septicemic p lague, or both. Cases were reported more frequently in males (58%), an d male mortality exceeded that of females (17 versus 11%). Ground squi rrels were the most frequently implicated sources of infection in case s associated with flea bites, and domestic cats were found to play an increasingly important role in transmission of disease to humans durin g these decades.