Dictionary > Prevalent


prevalent definition and example

adj., noun: prevalence
Definition: widespread; dominant; prevailing

Prevalent Definition

We can define “prevalent” as the most commonly found, being dominant or widespread, or describing the presence of a wide spectrum of a variety of a particular activity or property in a given population. It is the opposite of the words, rare, uncommon, infrequent, etcPrevalence, in turn, is a noun of it, which can be defined as the population that is grouped based on a variety of particular activities. The word origin of prevalent is from the Latin term “praevalēre”, meaning “to have superior strength” or “to prevail.

Example of prevalent in a sentence: English is the prevalent language in many parts of the world.
Explanation: The population of people who are proficient in the use of a particular language is prevalent because there are a variety of people who are proficient in that language.

Prevalent in biology

The current usage of the word “prevalent” in biology is similar to the general precept when used as a descriptive word. Prevalent as an adjective, for instance, describes the prevalence of a trait or a particular characteristic among a certain population or a community (which refers to the overall number of people who have an illness or health ailment at a given moment, typically a percentage).

The term “prevalence” refers to the condition of something being widespread and should not be confused with “incidence.” Incidence refers to the number of newly infected people over a certain period, whereas prevalence is a measurement of the total number of people that are afflicted by disease at a given point in time. Prevalence and incidence are both measurements of the illness. When discussing any prevalent diseases that continue for an extended period, such as HIV, prevalence is an important metric; however, the incidence is more important when discussing diseases that only last for a short period, such as chickenpox.

Another usage of prevalent is as a noun, which means a species that is widespread or dominant in a given geographical area. A dominant species may be defined in two ways — the species that is the most dominant (community dominance) or the species that has the most ecological impact (ecological dominance).

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Biology Definition:
Prevalent is a term that is used to describe something that is common or widespread. For example, the proportion of a population at a particular point in time that possesses a particular trait is referred to as the prevalence of that characteristic and it shows how much prevalent that particular trait is. As a noun, prevalent refers to a species that is widespread or dominant in a given geographical area.
Etymology: from Latin “praevalens”, meaning “superior” or “dominant”. 
Prevalent Synonyms: prevailing; widespread; predominant

Calculating Prevalence

When calculating prevalence, the number of known instances or conditions serves as the numerator, while the entire population serves as the denominator. For instance, type 2 diabetes in children that become prevalent between the ages of 2 and 12 is calculated in percentage — that is, the number of diagnosed cases in the said age group (numerator) divided by the total number of children in that age group (denominator) x 100%.

It is essential to have an understanding of the sickness burden in a community, either local or global. For example, the administration of an old people’s home has to know how many of the patients suffer from Alzheimer’s disease so that they can provide enough care. Legislators and public health experts use demographic statistics to prioritize financing for health initiatives like those targeted at reducing obesity or quitting smoking. Also, planners of healthcare systems and public health officials benefit much from the data to get funding for specialized services or health promotion initiatives.

Typically, the increasingly prevalent behaviors and illnesses at the national and state levels are computed by using data which is taken from the population by large health surveys, like National Health and Nutrition Examination Survey (NHANES).

How is the Prevalence Calculated?

To determine the prevalence, scientists select a subset of the entire population to study at random. It is more likely that the characteristics of a sample drawn at random will show the traits of the population as a whole. · The prevalence of a characteristic in a representative group is calculated by the number of individuals who have distinctive traits of interest in the samples in the numerator and the total members in the samples in the denominator. (NIMH, 2022)

Prevalence = (number of people in sample having characteristics ) / (total number of people in sample)

How Does Prevalence Reporting Work?

Prevalence can be expressed as a percentage (5 percent or 5 people per 100). It can also be written as the sum of cases per 10,000 or 100,000 people. The reporting of prevalence is based on the frequency with which the trait is observed in the population.

The methods for measuring and reporting prevalence, depending on the estimation period are as follows (NIMH, 2022):

  • Point prevalence

    Point prevalence refers to the proportion of a population that possesses a trait at a certain period. Consequently, it covers all past instances who continue to have the illness and are still part of the community. Imagine taking a picture of the population and determining the proportion of individuals who had the condition of interest at the moment of the snapshot. This is a useful method to conceptualize point prevalence.

  • Period prevalence

    Period prevalence is the proportion of a population that possesses a trait at any moment throughout a certain period. The phrase “past 12 months” is widely used. The difference between point prevalence and period prevalence is that the “point in time” refers to a longer period.

  • Lifetime prevalence

    The percentage of a population that has ever, at any point in their lives, possessed a certain characteristic is referred to as the lifetime prevalence.

What does prevalent mean in epidemiology?
Epidemiologists use the term “prevalence” to describe the percentage of a population that exhibits a certain illness or condition at a given moment or above the given period, which is known as point prevalence and period prevalence, respectively. It’s hard to specify prevalence with incidence, which looks at how many new incidents there are in a population during a certain time. Prevalence is mostly used in questionnaire research.

Prevalent Examples

Here are examples of the prevalent and prevalence as used in science, such as biology and epidemiology:

  • According to the reporting from the CDC, the prevalence of obesity among American adults in the year 2001 was roughly 20.9 percent.
  • The prevalent notion of non-randomness is used to describe the number of organisms in a particular habitat in which a particular disease is prevalent. For example, the prevalence of malaria is relatively low compared to the prevalence of tuberculosis.
  • A prevalent idea pertains to how widely accepted, favored, or practiced an idea is in a certain community. For example, the anti-vax belief is rooted in a prevalent idea in a community that has uncertainties surrounding vaccines. This kind of vaccine skepticism refrains individuals from such a community to get vaccinated.
  • An example of point prevalence is as follows. According to WHO, in 2018, 3.9 percent of adults in the African area were living with HIV. The point prevalence is estimated at 3.9 percent. Because 3.9 percent is so close to being equal to 1/25, we may report the example as follows: In the WHO African area in 2018, one adult in every 25 was living with HIV.
  • Figure 1 below is an example of point prevalence that shows the proportion of students in a group who reported having symptoms associated with seasonal allergies during the first week of May 2016.

    point prevalence of seasonal allergies diagram
    Figure 1: Diagram shows point prevalence of seasonal allergies. Image Credit: Wayne W. LaMorte, MD, PhD, MPH
  • Period prevalence: In Figure 2. the Framingham Het Study conducted in 1980 looked for cataracts in a total of 2,477 participants and discovered that 310 of those subjects had cataracts. Therefore, the prevalence was 310 out of 2,477, which equals 0.125.

    cataracts prevalence in 1980 diagram
    Figure 2: Diagram shows the period prevalence of cataracts in 1980. Credit: Wayne W. LaMorte, MD, PhD, MPH.
  • Another good example of period prevalence is the influenza virus. 25–30 percent of the world’s population had a severe disease as a direct result of the “Spanish” influenza pandemic that occurred prevalently from 1918 to 1919. In this particular example, the total number of people living in the United States between the years 1918 and 1919 is used as the denominator, while the number of people diagnosed with influenza serves as the numerator. This has been the most prevalent disease among the above-described population
  • The essence of determining prevalence is to achieve herd immunity. Herd immunity is a resistant population that protects its members from infectious disease. Evidence exists that many diseases have low transmissibility rates and may therefore be controlled by herd immunity. This is important because herd immunity protects against a wide range of diseases, and thereby protects the entire population from disease.

Answer the quiz below to check what you have learned so far about prevalence/prevalent.


Choose the best answer. 

1. Meaning widespread, dominant, common, or prevailing
2. Species that is abundant in a particular area
3. The proportion of a population that possesses a trait at a certain period
4. The proportion of a population that possesses a trait in the past 12 months
5. The number of newly infected people over a certain period

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  • Dictionary.com. (2022). prevalent. Retrieved 17 June, 2022, from https://www.dictionary.com/browse/prevalent
  • Encyclopædia Britannica, I. (2022). prevalence epidemiology. Retrieved 17 June, 2022, from https://www.britannica.com/science/parturient-paresis
  • hsph.harvard.edu. (2022). Prevalence and Incidence. Retrieved 17 June, 2022, from https://www.hsph.harvard.edu/obesity-prevention-source/prevalence-incidence/#:~:text=Prevalence%20refers%20to%20the%20total,a%20percentage%20of%20the%20population
  • NIMH. (2022). Prevalence. Retrieved 17 June, 2022, from https://www.nimh.nih.gov/health/statistics/what-is-prevalence
  • Quantifyinghealth.com. (2022). Calculate Prevalence. Retrieved 17 June, 2022, from https://quantifyinghealth.com/prevalence/
  • sphweb.bumc.bu.edu. (2022). Prevalence. Retrieved 17 June, 2022, from https://sphweb.bumc.bu.edu/otlt/mph-modules/ep/ep713_diseasefrequency/ep713_diseasefrequency3.html


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