Final answer:
An epidemic that spreads globally is called a pandemic. It crosses international borders and affects multiple continents or the entire world, with examples including HIV/AIDS and the flu.
Step-by-step explanation:
When an epidemic spreads across national borders, continents, or around the world, it is referred to as a pandemic. For instance, HIV/AIDS is an example of a pandemic disease, as is the case with novel influenza viruses that often become pandemic when they appear. These widespread outbreaks have a long history, with one of the most notable being the Black Death, a bubonic plague that devastated Europe.
Epidemics occur when there is a significant increase in the number of cases of a disease within a short time and localized area. When this outbreak extends over larger regions, such as continents, or even becomes global, it evolves into a pandemic. This expanded impact of the disease highlights the necessity for international cooperation in public health responses, including the sharing of medical information, vaccine distribution, and coordination of containment strategies.