Plague is a disease caused by the bacteria Yersinia pestis. The disease can be transmitted to humans by fleas that have also bitten an infected animal. Plague can also transmit to humans through direct contact with an infected animal or their fluids or contact with a person with pneumonic plague. Plague is rare in Ontario, with cases acquiring their infection via travel outside of Ontario. Symptoms include fever, headache, chills and abdominal pain. Antibiotics are used to treat plague.