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The subject of transmitted disease became relevant for all of humanity in late 2019 with the onset of COVID-19. As the disease spread and infected people all over the world, the word pandemic also gained prominence in our daily communications.
English includes different words to convey the geographic scale of disease: endemic, epidemic, and pandemic. At times they might still be confused or used mistakenly in describing the reach of an infection.
Let's further look at each term so you can apply it with precision in its proper context.
What Does Endemic Mean?
Endemic is an adjective that describes a disease with a constant presence in a particular area. For example, malaria is common in certain tropical regions but often rare in other parts of the world. We would therefore say that malaria is endemic to those regions.
Note again that endemic is used an adjective and not as a noun. The word also pertains to a disease and not to the region in which it exists.
Correct: Malaria is endemic in that sub-equatorial coastal region. (adjective)
Correct: Malaria is an endemic disease in that sub-equatorial coastal region. (adjective)
Incorrect: The malaria endemic is specific to that coastal area. (used as a noun)
Incorrect: Malaria is an endemic in that coastal area. (used as a noun)
Incorrect: That coastal area is endemic for malaria. (describes the region, not the disease) |
What Is an Epidemic?
An epidemic is the wider spread of a disease among a certain population or region at the same time. It affects a larger area and more people than a disease that is endemic does.
In other words, an epidemic occurs when an infectious agent such as a virus quickly becomes more pervasive both inside and outside of the limited area where it first existed.
For example, if a virus moved past its regular presence in one particular U.S. county and infected most or all of the state it is in where people had not yet been affected, it would grow from an endemic disease into an epidemic one.
The word epidemic comes from the Greek epidḗmios, which translates as "within the country, among the people, prevalent (of a disease)." Similar to endemic, epidemic originated as an adjective, but in the late seventeenth century it became common as a noun. Today it is used as both a noun and an adjective: an epidemic, an epidemic disease.
Some historical examples of epidemics include smallpox, cholera, measles, typhoid, polio, and drug-resistant tuberculosis.
You may also be familiar with the term epidemiologist (similar root), which refers to doctors and scientists who study the occurrence, control, and prevention of infectious diseases.
What Is a Pandemic?
If an epidemic widens from, for example, a state to an entire country or continent or the world, it becomes a pandemic. An exceptionally high number of people are affected. Because of its massive scale, pandemics are less common than epidemics.
The word pandemic originates from the Greek pandēmos ("of all the people"), which itself is from pan- ("all, every") and dēmos ("people"). Like epidemic, pandemic is used today as both an adjective and a noun: a pandemic, a pandemic disease.
Believed to have originated as a local virus, COVID-19 spread further into a country and moved toward other continents, making it an epidemic. Within months it affected most of the world, and in March 2020, the World Health Organization classified the disease as a pandemic.
Other historical examples of pandemics include H1N1 (2009-10), severe acute respiratory syndrome (SARS) (2003), HIV/AIDS (1981), H3N2 (1968), H2N2 (1957), and, notably, H1N1, or the Spanish Flu, which was the deadliest outbreak of the twentieth century, claiming 50 million lives worldwide.
The easiest way to approach and remember the terms is to identify them from smallest to largest: endemic > epidemic > pandemic. Note also that the words do not describe the severity of a disease but rather the degree to which it has spread.
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