Infectious diseases—some that ravaged populations in the Middle Ages—are resurging in California and around the country, and are hitting homeless populations especially hard.

Los Angeles recently experienced an outbreak of typhus—a disease spread by infected fleas on rats and other animals—in downtown streets. Officials briefly closed part of City Hall after reporting that rodents had invaded the building.

People in Washington State have been infected with the diarrheal disease shigella, spread through feces, as well as Bartonella quintana, or trench fever, which spreads through body lice.