You have likely heard of the term epidemic, and most certainly heard of pandemic considering we are in the middle of one currently. How about the term endemic?

While they all sound similar and are related, they do have different meanings and we would like to remove any mystery and confusion in these widely-used terms.

Why do these three words often confuse people? All three words contain -demic and are used to talk about disease, or specifically outbreaks of disease. The demic part of these three words comes from the Greek dêmos, “people of a district.” The different meanings are a function of the first three letters.

What does this mean for the veterinary community?

Endemic refers to the constant presence of a specific disease within a geographic area. It’s a disease that is normal and commonly found in a particular location, region or specific population. So what we would consider normal in a given area during a particular time of year. We would say that strangles in horses is endemic in Kentucky. We see horses every year all over the state that need veterinary care for this disease.

Epidemic means that an increase (usually suddenly) in the number of cases of disease in an area is higher than what we normally expect to see (endemic). An example of this would be the outbreak of African Horse Sickness in Thailand. While considered endemic in sub-Saharan Africa, the outbreak in Thailand this year has caused hundreds of deaths.

Pandemic is an epidemic that has spread over a very large area. Academically, this could mean a disease that is prevalent through an entire country, a whole continent or globally (COVID-19). Typically, the word is generally reserved for diseases that have spread across a continent or the entire world. The World Health Organization (WHO) specifically defines pandemic as “a worldwide spread of new disease.” The current COVID-19 pandemic has had a major impact in the veterinary community.

According to the American Veterinary Medical Association, 98% of veterinarians were limiting client contact due to COVID (https://www.avma.org/resources-tools/animal-health-and-welfare/covid-19/...). We are seeing limited human visitation with their pets, postponement of spays/neuters and routine check-ups. Veterinary drug and equipment shortages have occurred where production has been hampered by COVID and demand increased by COVID, for example, with personal protective equipment. Drugs and equipment that was destined for the veterinary market is being diverted to the COVID crisis and has saved human lives.

The take home message

A small camping fire that you take care of and deal with constantly is endemic. If something is spreading like a forest fire, it’s an epidemic. If the entire forest is on fire and has spread all over, causing major impacts, it’s a pandemic.

Jackie Smith, MSc, PhD, MACE, Dipl AVES, is an epidemiologist based at the University of Kentucky Veterinary Diagnostic Lab. Emma Adam DVM, PhD, DACVIM, DACVS, is based at the University of Kentucky Gluck Equine Research Center and Veterinary Diagnostic Lab and is responsible for research and serve as a veterinary industry liaison.