A disease that has spread over several countries and continents affecting a large number of people is called a

Plague is a disease that affects humans and other mammals. Humans usually get plague after being bitten by a rodent flea that is carrying the plague bacterium or by handling an animal infected with plague. An outbreak is when an illness happens in unexpected high numbers. It may stay in one area or extend more widely. An epidemic is when an infectious disease spreads quickly to more people than experts would expect. It usually affects a larger area than an outbreak. A pandemic is a disease outbreak that spreads across countries or continents. It affects larger number of people and takes more lives than an epidemic. The World Health Organization (WHO) declared COVID-19 to be a pandemic when it became clear that the illness was severe and that it was spreading quickly over a wide area in a less time.