Epidemiology: what is it and how does it study diseases?

What is epidemiology and what methods does it use to study diseases and pandemics?

A few weeks ago, a certain virus that many of us thought was not going to be a big deal has ended up giving us a "pleasant" surprise inviting us to stay at home. Not out of laziness or because it has not been a good day, but because it turns out that the street is, right now, potentially contagious.

Given the alarming situation we find ourselves in, it is not surprising that people are asking about the symptoms, incidence, progression of infection, incubation and elimination period and other factors of the COVID-19 virus.

These questions have their own field of study. Epidemiology is the biomedical science that studies the distribution, incidence, progression, incubation period, elimination and other factors of the COVID-19 virus.The following is a more in-depth look at what it is all about, and how it affects the frequency and conditions for the onset and progression of a disease.

What is epidemiology?

Epidemiology, (from the Greek "epi", "about; "demos", "people"; and "logos", "science") is the study of the occurrence and distribution of health-related events, states and processes in the population. In other words, it is the medical science that studies diseases and their evolution in the population as a whole.. Epidemiologists study the distribution, frequency and factors that influence and determine the progression of diseases in a group of people.

The position that epidemiology occupies in the biomedical sciences is very important, given that it it serves as a bridge between the health sciences and the social sciences.. It integrates both biomedical and social methods and principles to study health, control diseases in the population and study their socioeconomic and biomedical effects.

Although epidemiology originally emerged to study epidemics of infectious diseases, such as cholera, the Spanish flu or the plague, today it also includes diseases not necessarily due to bacteria and viruses, such as lung Cancer caused by smoking, addictions, as well as the emergence of mental disorders such as bipolar disorder, anorexia nervosa or depression, among others.

What is taken into account when studying diseases?

Epidemiologists, when studying a disease, whether caused by a living pathogen such as bacteria or by habits in the population, such as sedentary lifestyles and smoking, take into account a series of patterns of the medical or psychiatric condition to be studied:

1. Time

Time refers to when it arises, especially if it is a disease with a possible contagious cause.The peak of the disease may occur at a certain time of the year.

2. Place

It is the physical place, such as a city, a country, the characteristics of the area in which there have been more cases.…

3. People

People refers to those who are more likely to manifest a certain biomedical condition, i.e. the risk group.

Normally, in contagious diseases, the groups most at risk are newborns and the elderly.

Epidemiological methodology

Epidemiological methodology uses the observational scientific method because this discipline, in order to increase its knowledge, has to use real cases that have occurred in the population. That is to say, it looks at how many new cases of the disease there are, what individual characteristics cause these cases to have manifested the disease, what has caused there not to have been such a high incidence elsewhere?

The epidemiological method uses mainly quantitative techniques. Epidemiological studies do not alter or manipulate the factors acting on individuals, unlike a laboratory experiment.Unlike a laboratory experiment, in which the characteristics of the person, the type of stimuli or environmental factors to which he or she is subjected, among others, are controlled.

Objectives

Epidemiology is a fundamental area of the biomedical sciences, since it provides insight into the development of medical conditions, whether or not they are caused by infectious agents. This discipline has the following objectives.

1. To establish the magnitude of the disease

It aims to to measure what is happening in the population, what are the mortality, incidence and prevalence rates of diseases, as well as the prevalence of infectious agents.and the prevalence of risk factors.

All this serves to know the specific characteristics of health or disease in a population, in addition to being able to monitor over time how these characteristics are changing.

For example, epidemiology would study why there is more mortality in a certain region than in another, what genetic and environmental factors make a population more vulnerable, or what dietary or risk-taking habits would explain the incidence of the medical condition.

2. Identifying the determinants of the disease

As we have already seen, since its beginnings, epidemiology has tried to discover why a certain state of health appears and what causes influence the pathological process.

In essence, it is responsible for identifying risk factors for the manifestation of a medical disease or psychological disorder..

3. Completing clinical pictures

In clinical medicine, epidemiology has a very useful application, since it makes it possible to specify, by means of epidemiological and statistical criteria, what the patient is suffering from.

An example of this was the case of rapeseed oil poisoning.. Through epidemiological research, it was possible to discover that the disease manifested by thousands of people was caused by having consumed this particular oil.

4. Detecting new diseases

The appearance of new cases of a disease that was previously unknown is studied by means of the epidemiological method.

This was the case with HIV/AIDS.. Patients were found to manifest a rare pneumonia, which only affected people who had symptoms of immunosuppression.

5. Evaluating the effectiveness of health intervention

Epidemiology is applied to determine the efficacy of any type of health intervention, whether for prevention or treatment.whether for prevention or treatment.

6. Contribute to health planning

Although the above applications already contribute to health planning, epidemiology is also used, specifically, to understand the specific needs of health services, for example, in designing health plans.

In addition, it is also is also used for the evaluation of results following health intervention policies, analyzing the objectives set in the health policies.It is also used for the evaluation of results after health intervention policies, analyzing the objectives set in previous plans.

7. Contribute to training

Epidemiology not only aims to find out how a disease occurs, what is its prevention, which population is at risk and other aspects directly related to the biomedical condition.

It also also aims to train health professionals so that, should the disease appear, they know, by consulting the biomedical literature and knowing the symptoms of the health condition in question, what to do and how to prepare.

Some key terms

Within the language of epidemiology there are some terms that have a specific meaning when talking about pathological processes. Some of these terms are discussed in more detail below.

1. Epidemic

A disease is considered an epidemic when there is a very high number of people presenting this medical condition simultaneously..

2. Pandemic

A pandemic is an epidemic of large proportions, which spreads widely, becoming present throughout the world. An example of this is the case of COVID-19 in March 2020.

3. Endemic disease

An endemic disease is one that occurs in greater numbers in a given population, although it does not necessarily imply that it has been present throughout the world.It does not necessarily imply that it has manifested itself in all individuals.

An example of an endemic disease is the case of thalassemia, a type of anemia found in many Mediterranean countries, with more cases found in southern Spain and Italy.

4. Incidence of a disease

This term refers to the number of new cases of an individual disease in a population over a given period of time.

5. Prevalence

The prevalence of a disease is given by the total number of new and existing cases detected in a given population over a given period of time.also over a given period of time.

6. Outbreak

An outbreak is understood as the appearance of new cases in a specific region, generally during a short period of time.

An outbreak means that more cases are occurring than previously, although it does not necessarily refer to the appearance of a new disease. It may be that the same disease occurred previously, but very sporadically.

About contagious diseases

To cause disease, a pathogen, such as a bacterium or virus, needs to find an individual to host. There, it grows and reproduces, affecting the individual's health and producing its own symptoms, it grows and reproduces, affecting the health of the individual and producing the symptoms of the disease..

It should be said that, although there are diseases that are fatal, in most contagious diseases, if the host dies, so does its tenant, which is not beneficial. If they have to kill the host, these organisms must first be able to reproduce and move on to another organism, otherwise they will become extinct.

It is for this reason that most host-dependent pathogens host-dependent pathogens need to adapt to and coexist with the individual in which they are hosted.. This is not a symbiotic relationship, but rather parasitism, since the host individual, even if it does not die, will be harmed.

Once the pathogen is well adapted in the individual, it takes what it needs to continue living and uses the host's own biological structures to nourish itself or reproduce, as would be the case of viruses with cells during viral reproduction. The damage that can be caused by these pathogens is various, ranging from simple temporary symptoms to chronic infections that must be treated urgently and intensively.

Bibliographic references:

• Hernández-Aguado, Ildefonso, Lumbreras, Blanca, & Jarrín, Inmaculada. (2006). Epidemiology in the public health of the future. Revista Española de Salud Pública, 80(5), 469-474. Retrieved March 19, 2020, from http://scielo.isciii.es/scielo.php?script=sci_arttext&pid=S1135-57272006000500005&lng=es&tlng=es.
• Fernández, E. (n. d.). what is epidemiology for? esteve.org. Retrieved from https://esteve.org/wp-content/uploads/2018/01/13113.pdf.