Epidemic vs Pandemic

Epidemics and pandemics are both words used to describe a disease spreading through the population. Both terms come from the Greek language,

The word ‘epidemic’ is derived from the prefix ‘epi-’, which means ‘upon’ or ‘on top of’, and the word ‘demos’, which means ‘people’. Essentially, it is something put upon the people, though in English, it mainly refers to disease outbreaks. Sometimes, it can be used as a metaphorical outbreak, such as an “epidemic of fear”.

Epidemics are outbreaks of diseases that affect many people in a population and begin to spread rapidly. In order to be considered an epidemic, it must affect a certain number of people in a short time, typically two weeks.

The number of people that must be affected in order for it to be classified an epidemic depends on the disease itself. It is based on the number of people who are expected to be infected with the disease per year, and if there are significantly more cases than expected, then it will be termed an epidemic. If the disease does not typically affect a lot of people at a time, such as meningococcal infections, fifteen cases per ten thousand people in two weeks could be considered an epidemic. A few cases of smallpox in the world would be considered an epidemic, as it has been eradicated and it is likely to spread very quickly if not caught immediately.

However, many cases of a disease that is fairly normal in a large population, such as the common cold, would not be considered an epidemic simply because a lot of people are expected to get it per year. When a disease is maintaining itself in the population and the number of people getting infected per year is roughly the same number of people who had it the previous year, then it is considered an endemic disease – the ‘en-’ prefix meaning ‘in’, as in ‘in the people’. If the people who have the disease are increasing each year, whether steadily or exponentially, then it is more likely to be considered an epidemic.

Epidemics are always infectious, but they do not necessarily need to be contagious – which means that they do not need to be directly transmitted though skin touch, airborne, or easily caught from another person. Diseases with other methods of transmission, such as through insects, can still be considered an epidemic if they spread quickly. West Nile Virus is spread primarily through blood contact with another person or with mosquitoes, and it is still considered an epidemic. However, most epidemics are caused by contagious diseases.

‘Pandemic’ is also derived from the root word ‘demos’. The prefix, ‘pan-’, means ‘all’. It is something involving all people. Unlike the word ‘epidemic’, it can be used to talk about anything that is widespread over many people, such as fashion.

A pandemic is a much larger version of an epidemic, or may cover several epidemics in a certain area. If an epidemic covers many different countries or spreads to more than one continent, then it is very likely to be a pandemic. Like an epidemic, a pandemic must be infectious and spreading rapidly. The number of people infected or killed by the disease does not matter as much as what the rate of spread is and how far it has spread, so a disease that has only killed a few thousand people may still be considered a pandemic.

To summarize, an epidemic is a disease that spreads more rapidly than expected in the population. The expected rate of infection is based on how common the disease is and how many people normally get infected with it. When the epidemic shows up in many countries or on multiple continents, then it may be considered a pandemic.