I think they were referring only to human case of the plague in the US.
That is possible. This link has some data on it but since its not broken down by year its kind of impossible to tell when the last case was. It suggests there are anywhere between 1-17 cases per year.
>Over 80% of United States plague cases have been the bubonic form. In recent decades, an average of seven human plague cases have been 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. It occurs in both men and women, though historically is slightly more common among men, probably because of increased outdoor activities that put them at higher risk.
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