Endemic, Epidemic and Pandemic: What’s the Difference?

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Endemic, Epidemic, and Pandemic: What’s the Difference?

The question that has yet again sprung up is whether the coronavirus outbreak is epidemic, endemic, or pandemic.

When you are casually using the word epidemic, then it may not require a lot of intricacies. However, when it comes to the public health response, disease prevention, and better control of diseases, knowing the real meaning of the words is very important.

To understand the difference, it is essential to know what they are. Let’s first check the etymology of the words to have a clearer idea.

The Etymology of the Words: Endemic, Epidemic, and Pandemic

The words epidemic, endemic, and pandemic come with the element “dem,” derived from the Greek word “demos,” which means people or district. Now, that we know the meaning of a part of these words, let’s take a closer look:

Endemic = en + demos. While “en” means in, “demos” means “people or district.”
Epidemic = epi + demos. While “epi” means among, “demos” means “people or district.”
Pandemic = pan + demos. While “pan” means all, “demos” means “people or district.”

The Outbreak of a Disease and Common Confusion

A disease outbreak takes place when it happens in higher numbers than the expected extent in a community or a particular geographic region or a season. The outbreak can sometimes extend several geographic locations, countries, continents, or even across the world. A disease-outbreak can take place for several days to certain years.

A disease can be infectious or non-infectious.

Arthritis, asthma, cancer, and many more are non-infectious diseases. Common cold, pneumonia, mumps, measles, smallpox, tuberculosis, and many other conditions that one catches up easily through contamination, touch/contact, or droplet infection (that are communicable) are infectious ones.

Infectious diseases can spread through coughing or sneezing (droplet infection), kissing or other direct contacts, indirect contact, and other person-to-person contacts. Infectious diseases are also spread through animals.

The bubonic plague in 1348 that killed more than 20 million people and ended 1/3rd of the European population was spread through fleas and rats.

Other diseases that are spread through animals are malaria (mosquitoes), Lyme disease (ticks), and flu viruses (ducks and pigs). Non-living sources such as water and food can also spread infection. While meat can act as a carrying agent of salmonella, cancers can be caused by hazardous chemicals.

Endemic

Endemic is an adjective word that is usually used for referring to a disease or condition that is found in a specific area or among particular people.

Examples:

There are many malaria-endemic countries where transmission of malaria takes place regularly in some regions of a country. Malaria doesn’t occur in all parts of the country at the same time. It takes place locally, and transmission extent is also limited to the local boundaries, say a village, within a few neighboring villages, or a particular zone.

Polio has now become endemic in some regions of specific countries such as a particular village(s) or a zone(s) in Pakistan, Afghanistan, and Nigeria.

Epidemic

The word “epidemic” is used to describe a problem that has grown out of control. In terms of the medical fraternity, a disease is called an epidemic when there is a widespread occurrence of it within a community at a certain point in time or time period. An infectious disease that usually spreads rapidly among people within a short time is referred to as an epidemic.

Examples:

In the United States, especially during the winter season, influenza epidemics take place. They usually take place almost on an annual basis from late-December to early-February.
In Michigan, the death toll had taken a tragic turn when an intense flu epidemic spreading across the nation took a deadly turn in the state.
H1N1 Flu Epidemic filled up the Texas hospital beds and ERs.

Pandemic

The word “Pandemic” is used when there is a geographic spread of disease. An infectious disease is generally called pandemic when it affects the entire world or an entire country.

Examples:

When an infectious disease infects a large number of people beyond a region, countrywide, or worldwide, it is called a pandemic. There have been many such instances across the world.

The worst ever pandemic in known human history is the Black Death, which killed over 75 million people across three continents.

Other cases are:

A small-pox pandemic took place during 1870-1875 after the Franco-Prussian War that had killed around 500,000 people.
A Spanish influenza pandemic took place in 1918 that had killed around 50 million people.
A global disease outbreak such as HIV/AIDS in recent years is one of the worst and most destructive pandemics in history.
In 1957, Asian influenza reportedly killed around 2 million people.
In 1968, the Hong Kong influenza killed around 1 million people.

WHO’s Influenza Pandemic Alert System: Phases and Scale

The World Health Organization (WHO) has provided a scale (from Phase-1 to Phase-6) for alerting people and health-care professionals about the extent of a pandemic. While Phase-1 indicates a low-risk flu pandemic, Phase-6 refers to a full-blown pandemic.

So how are the phases described?

Phase 1: A virus in animals causing no human infections.

Phase 2: Infection caused in human beings by an animal flu virus.

Phase 3: Small cases or sporadic spread of disease in human beings are reported at this level. Community-level disease outbreaks have still not reached due to human-to-human disease transmission.

Phase 4: In this phase, the risk of an imminent pandemic has increased but still not certain that it will spread definitely.

Phase 5: Human-to-human disease transmission starts happening in more than one country in a WHO region.

Phase 6: The community-level outbreaks take place in at least one country belonging to another WHO region. This means that a global pandemic is on its way.

Can Wuhan Coronavirus be called a Pandemic?

The current outbreak of Wuhan Coronavirus (also called novel coronavirus or 2019-nCoV), which was first reported from China’s Wuhan on December 31, 2019, and is called by a scientist as “mild pandemic.”

Director of the National Institute of Allergy and Infectious Disease, Dr Anthony S. Fauci, has said that 2019-nCoV is extremely transmissible and is almost certainly going to be a pandemic.

As the World Health Organization (WHO) has defined pandemic as “the worldwide spread of a new disease,” referring Wuhan Coronavirus outbreak, a pandemic will require a more worldwide outbreak.

The WHO researchers believe that, on average, a coronavirus-infected person transmits to 1.4 to 2.5 other people, making WHO declare 2019-nCoV an international public health emergency on January 30.

Will Wuhan Coronavirus’ (2019-nCoV) Deadly Spree End?

There are currently four other strains of human coronaviruses present, and they are OC43, 229E, HKU1, and NL63. All of them are endemic, which means that they are permanently present. Experts believe that the Wuhan Coronavirus or 2019-nCoV has enough features to be considered as endemic.

There is a second possibility. It will never disappear and either become seasonal in occurrence or mild. The third and most desired possibility is that the 2019-nCoV coronavirus plays itself out through proper public-health interventions. For controlling 2019-nCoV, a vaccine is required. Five pharmaceutical companies have announced their plans for manufacturing a vaccine for Wuhan coronavirus. If they succeed, then it will help to decrease the number of people “susceptible to the coronavirus and create a “sustained firewall” against its further spread.