What term describes diseases that can spread rapidly across countries?

The term that accurately describes diseases that can spread rapidly across countries is pandemic diseases. A pandemic involves the widespread occurrence of an infectious disease across multiple countries or continents, significantly affecting a large number of individuals. This classification highlights the potential for quick and extensive transmission, often due to factors such as globalization, travel, and interconnectedness of populations.

In contrast, endemic diseases are those that are consistently present in a particular region or population but do not spread widely. Localized diseases are typically confined within a specific area and do not reach a widespread level of transmission. Chronic diseases are long-lasting conditions that may require ongoing medical attention but are not infectious, thus not applicable to the context of rapid spread across nations.