Without an Approved Vaccine, Plague Cases Continue in 2024

The U.S. Centers for Disease Control and Prevention (CDC) says the Plague was first introduced into the United States in 1900. The plague bacterium (Yersinia pestis) is transmitted by fleas and cycles naturally among wild rodents. 

Over the decades, the Plague spread from urban rats to rural rodent species and became entrenched in many areas of the western U.S.

Almost all of the cases reported in the last 20 years have occurred among people living in small towns and villages or agricultural areas rather than in larger towns and cities, says the CDC.

As of 2024, the CDC estimates that seven human cases of Plague occur in the U.S. each year.

Recent plague cases include the Pueblo Department of Public Health and Environment confirming a human case of Plague in a Pueblo County resident on July 9, 2024.

And in February 2024, health officials in Oregon reported a case of bubonic Plague in a resident who they said likely contracted it from a pet cat.

Globally, the most human plague cases since the 1990s have occurred in Africa.

From a prevention perspective, plague vaccines are no longer available in the U.S. However, plague vaccine candidates are in development but are not expected to be commercially available in the immediate future.

In March 2023, the first mRNA-based, lipid nanoparticle vaccine was found effective against lethal bacteria in mice.