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WASHINGTON – Health officials say they recently recorded four cases of the plague.

Primary Pneumonic Plague is rare.

In fact, there have been fewer than 100 cases reported in the United States in the past century.

This small outbreak occurred in Colorado last summer starting with a sick pet dog who was euthanized.

The dog’s owner and two people who worked at the veterinary clinic then became ill.

Officials say a fourth person may have contracted the illness from the dog or the dog’s owner.

All four were given antibiotics and recovered.

Plague bacteria usually spread through infected rodent fleas.