The 3 differences between infectious and non-infectious diseases

Health is one of the most important issues in modern society, especially when we lose it sporadically or permanently. We are beings that relate to the environment, and therefore, we are at a constant riskof suffering both intrinsic and extrinsic damages.

Like all species on the planet, humans have development as their ultimate goal: we are born, we grow, we reproduce and we die. Disease is as essential a part of life as health, for it is this silent threat that gives meaning to existence and circumscribes it in a concrete and finite period.

Thus, understanding the differences between infectious and non-infectious diseases is a question that goes far beyond a linguistic conglomeration. As obvious as the subject may seem, we assure you that the world underlying these terminologies will surprise you.

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How is an infectious disease different from a non-infectious one?

According to the World Health Organization (WHO), the disease is defined as “an alteration ordeviation of the physiological statein one or more parts of the body, for generally known causes, manifested by characteristic symptoms and signs, and whose evolution is more or less predictable”. From a slightly more analytical point of view, we can define this state as a lack of normality.

That’s right: the disease is physiologically abnormal, a transitory or definitive situation in which the patient shows symptoms and signs that escape the “physiological mean” expected for him in a specific time and space. This person may present signs, which are objective manifestations observed on medical examination (for example, red spots) or symptoms, which refer to the subjective perceptions of discomfort perceived by the individual (for example, the headache cannot be seen).

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As disease is as essential a part of life as breathing, we are not surprised to learn thatmore than 90% of the world’s population has some type of pathology ofvarying severity. We go further, as it is estimated that only 5% of human beings alive at any time and anywhere are “completely healthy”. Once the concept of disease is put into perspective, let’s explore the 3 differences between infectious and non-infectious diseases.

1. The key is in the causative agent

In the first place, an infectious disease is defined as one that is the product of, forgive the redundancy, infection by a microorganism. These microscopic beings are grouped under the common term “germ”, a word that brings a lot of confusion.

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This is because we must be clear thatnot all germs or microorganisms are pathogenic: for example, about 500 species of bacteria live in our large intestine and help us break down food, obtain vitamins and give us protection and immune development. Some germs can be commensal or evensymbiontswith humans, especially if we talk about bacteria. Therefore, we can affirm that it is the pathogenic germs that produce damages in the individual when multiplying inside or on him. We find several microscopic beings in this category:

• Bacteria: cause infectious diseases such as tuberculosis.
• Viruses: do not require presentation, because from influenza to HIV they cause an infinity of diseases.
• Fungi: cause mycosis, such as aspergillosis or candidiasis. They usually settle in mucous membranes or wet areas.
• Protozoa: larger and more complex but still microscopic beings, which cause diseases such as toxoplasmosis or giardiasis.

Again, it is essential to emphasize that not all germs or microorganisms are pathogenic, as there are even viral strains that do not cause any type of damage to the host. Several studies increasingly explore the function of some supposedly harmful agents, and it is being discovered that sometimes they can be much more beneficial than we initially thought. Isn’t it surprising to you that 8% of the human genome is of viral origin? This figure speaks for itself.

On the other hand and changing third, a non-communicable or non-infectious disease (NCD) is one that, worth the redundancy again, is not caused by an infectious process. In this case we are facing pathologies that are usually characterized by a certain chronicity, that is, they do not disappear in a few days as is the case of pathologies of infectious origin. In this case, we have four clear causative agents, although there are thousands more:

• Tobacco consumption: 1300 million smokers are distributed throughout the planet.
• Unhealthy diets: more than 650 million adults are obese today.
• Physical inactivity: sedentary lifestyle is behind all kinds of cardiovascular diseases, which are the main cause of death.
• Alcohol abuse: 237 million men and women have some type of alcohol use disorder.

Clearly and as we can see, we are facing a series of pathologies that are closely linked to the unhealthy and sedentary habits so established in our society, especially in high-income countries. In any case, not all NCDs correspond to social and environmental factors, since genetic diseases are also included in this group.

Differentiating these pathologies from the individual’s environment is wrong, since it is known (and is still being investigated) that the environment of the patient with a genetic predisposition to a certain pathology can play an essential role in its development in many cases. Even so, we believe that the general idea is clear: infectious diseases are produced by germs, while non-infectious diseases are usually related to bad lifestyle habitsand factors intrinsic to the individual.

2. Infectious diseases are communicable; the others do not

As obvious as it may seem, the most essential feature of infectious diseases is their transmissibility, right? An infectious disease is considered transmissible or contagious when it spreads directly or indirectly from one person to another, usually by secretions, contact with skin, mucous membranes and fluids or by microaerosols.

Noncommunicable infectious diseases occur in exceptional situations, for example, when a vector such as a fly carrying the pathogen is required or after a bad blood transfusion to a patient (it does not involve contact between two people). In any case, and in a theoretical framework, any infectious disease can invade the organism if the right vehicle is used.

We believe that the difference is self-explanatory: non-infectious diseases are not transmitted between humanseither from vectors or exceptional situations. A pathology such as heart failure or cancer, no matter how much you come into contact with a person who suffers from it, is still exclusive to the individual.

3. Non-infectious diseases cause more deaths

It is striking to know that, in 2016,72% of deaths were due to noncommunicable diseases (NCDs). This is not surprising when we consider that ischemic heart disease and heart attack are the two leading causes of death worldwide. This translates, estimatedly, into more than 38 million people dying each year from non-infectious causes. Of course, these figures require qualification.

Although more than 70% of deaths worldwide are from NCDs, in low-income countries with poor health infrastructure this percentage rarely reaches 40%. In impoverished regions, respiratory tract infections are the leading cause of death, causing more than 70 deaths per 100,000 inhabitants annually. This group of pathologies is followed by diarrheal diseases, which without treatment can have devastating effects on the patient (especially in infants).

What conclusions do we draw from this data? The thing is clear: illness is also a class issue. The members of Western countries can “afford” to die of old age generally, which makes cardiovascular diseases the cause of our death in most cases. It is no coincidence that in Cameroon the average life rate is 59 years and in Germany it exceeds 81 years.

Summary

As we have seen, no matter how much we create settled knowledge regarding the world of diseases, there are still figures and concepts that surprise us. Not all infectious diseases are transmissible and not all germs are bad, for example.