Why Do We Fall ill?

Disease and Its Manifestation

How do you know a person is ill? How do you know a person is suffering from a certain disease? Obviously, the individual’s body will provide some sort of indication or signs that the body is not functioning well. Hence, the body will not function abnormally or unusually. This is nothing but the manifestation of diseases or symptoms/medical signs of diseases. Let us study more about diseases and its manifestation in detail.

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Manifestation of Diseases

We know there are many tissues in our body. The tissues collectively make up the organs or the physiological system of a body of an individual. These organs together form organ system and carry out distinct functions. For example, bones and muscles together form musculoskeletal system.

The musculoskeletal system helps in the movement of the body and holds together the body parts. Similarly, stomach and intestine make up the digestive system. This system helps in digestion process. Similarly, there is cardiovascular system, lymphatic system, nervous system, urinary system, endocrine system, etc.

If an individual is suffering from any disease, the functioning of the system or the system’s appearance will vary from normal. All these changes develop signs and symptoms. This is known as the manifestation of diseases. For an example cough, headache, inflammation, fits, vomiting, wound with pus, or even loose motions are symptoms that indicate that a person may be is suffering from a specific disease.

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Symptoms or manifestation are the signs indicating an underlying disease such as abdominal cramps, headache, fever, among numerous other symptoms. Symptoms depend on the type of disease. Two or more disease can have common symptoms. Therefore, symptoms of diseases cannot indicate the exact disease.

For instance, if a person is having a headache, he/she may have normal stress, fever, migraine, or even in rare cases, it is a symptom of meningitis. This is why physicians search for signs of diseases on the basis of symptoms. However, to pinpoint exact disease physicians/doctors runs a series of the laboratory test on the person.


Symptoms of Malaria [Wikipedia]

Difference between Signs and Symptoms of Any Disease

Symptoms of Disease Signs of Disease
Symptoms are the changes that any patient experiences before or during the disease. However, a doctor cannot see or observe it so the patient has to inform the doctor about the symptoms. Signs refer to the changes in the normal functioning or structure of the body. A physician/doctor can easily notice signs in the patient’s body. Signs include rashes, inflammation, swelling, change in the colour of the skin, etc.




The literal meaning of disease is “disturbed ease” or feeling uncomfortable. Hence, disease refers to malfunctioning of any part of the body due to one or more reason. The disease can generally be of two types- acute disease and chronic disease.

Acute & Chronic Diseases

The manifestation of the disease varies on the basis of many factors. The most common factor to decipher a disease is the duration of the disease. The duration of certain diseases lasts for a short duration. These diseases are called acute diseases. For example, common cold affect for a few days.

However, there are another set of diseases that can last for a very long duration of time, sometimes even for the lifetime. These are known as chronic diseases. For example, elephantiasis, a type of infection, prevalent in some regions of India.

Relation of Poor Overall Health & Chronic Diseases

Acute and chronic disease will have different effects on an individual’s body.  We know that any type of diseases, be it acute or chronic, will affect the specific part of our body and it will also affect a person’s overall general health. Every function of an individual’s body is essential for general health.

Thus, if a single part of the body and its function is not normal, it will affect the overall health. However, in case of acute diseases, the effect will be over in a short duration without causing a major effect on the overall health of a person.

For example, all of us often suffer from fever, cough and cold but we get better in about a week without facing any lasting effects on our health such as breathlessness, weight loss, etc. In case of the chronic disease like tuberculosis, a person is ill for a very long duration. Furthermore, the effects are constant and last for long like weight loss, tiredness, etc.

Hence, if we suffer from an acute disease, we might not go to school for a few days here and there but if we suffer from a chronic disease, it will decrease our ability to learn and follow the lessons taught in school. Thus, chronic diseases will have a drastic long-term effect on the overall poor general health of the body.

What are the Causes of Diseases?

Imagine a person is suffering from Malaria. What is the cause? Of course, we can say the mosquito bite. What happens when a person is bitten by mosquitoes causing malaria? Malaria is a mosquito-borne parasitic infection spread by mosquitoes that carry the pathogen “Plasmodium,” single cell parasites.

These parasites are present in mosquitoes and upon biting a human is transmitted to the human thereby causing Malaria. So, we can say the causes are the vector and pathogen.

  • Pathogen- Disease-causing infectious agent or organisms
  • Vector- Insects or animals carrying the pathogen

However, causes can be at different levels. The immediate cause can be the pathogen or the vector. Consider a baby suffering from frequent loose motions. The cause can be the infection due to the virus. But how did the virus enter the body? Moreover, there are so many babies, why did the virus infect the particular baby?

This means that baby might not be healthy enough. Hence, it is more prone to diseases during exposure to a risk. Another reason can is the baby is not getting proper nourishment. This is a second level cause. Why is the baby not getting proper nourishment? So, the baby might be poor enough or it may have some genetic defect that is making the baby more prone to loose motions when attacked by a virus.

Therefore, the baby might drink unclean water. Why the baby drinks water that is not clean? It may be because of lack of proper public services, and poverty near the area where the baby is living. This is the third level cause. So, causes of any disease can either be immediate or contributory. Contributory causes include unclean water, poverty, genetic, etc.

Infectious & Non-Infectious Disease

By now we know that public health and community health are the essential factors to consider while finding the causes of any disease. Hence the immediate cause can be of two primary types-infectious and non-infectious types. The diseases will vary in the manner they are spread, treatment method, and the prevention measures at the community level.

  • Infectious Diseases: The cause for this type is infectious agents like microorganisms or microbes. The disease occurs due to microbes. Microbes are capable of spreading in the region, the disease can spread among them. Therefore, we term it infectious diseases. Examples include bacteria, protozoa, fungi and virus, Diseases caused are diarrhoea, tuberculosis, dengue, malaria, hepatitis, etc.
  • Non-Infectious Disease: Diseases occurring due to abnormal functioning of any organ refers to non-infectious disease. Microorganisms are not the cause of this disease. Many factors can be the cause of this category of diseases such as wrong lifestyle, genetic, etc. Examples include diabetes, arthritis, haemophilia, heart diseases, etc.

Organ-Specific & Tissue-Specific Disease Manifestations

By now we know how the organisms (microbes) enter a human body in different ways. However, a human body is very large in comparison to a small microscopic organism. Hence, they can travel inside a body and move to different places such as organs and tissues. However, these microbes do not go to same tissue or organ.

Different species of microbes are evolved in such a way that they are very selective and they will enter different parts of the body. Point of the entry forms the basis of the selection. For instance, if the entry of the microbe is through the nose, it can likely go to the lungs. Such as bacteria that enter through the nose in case of tuberculosis.

Similarly, if the microorganisms enter via mouth it can possibly enter gut lining such as bacteria causing typhoid. Furthermore, the microbes entering via mouth can enter into liver and cause jaundice. However, this is not the case for all infectious organisms.

For example, malaria-causing microbes “plasmodium” enter via mosquito bite and then move to the liver, and then to red blood cells. Brain fever, Japanese encephalitis, causing virus will enter via a mosquito bite and then infect the brain.


Tuberculosis causing bacteria [Wikipedia]

Mechanism of Organ-Specific & Tissue-Specific Disease Manifestations

Manifestations of any disease will vary on the basis of tissue or organ a microbe is targeting. Symptoms if the lung is the target will be shortness of breath and cough. Symptoms if the brain is the target will be fits, headaches, vomiting, unconsciousness, etc. It is easy to understand the manifestations of any disease if we know the target organ and their function.

However, there are certain common effects that the immune system of the body produces against any foreign particles causing infection. A healthy and active immune system recruit cells to kill the microbes present in the infected region. This process of recruitment is known as inflammation.

The killing of the microbes by the immune system will produce certain temporary effects in the area of infection such as swelling, pain, fever, etc. However, in some cases, tissue specificity of the infection can produce the general effects. For instance, an HIV patient faces minor infections every day because the infection damages the immune system and its function.

Thus, the body is no longer capable of fighting off the common infection. Hence, even a minor cold in these patients can lead to pneumonia or a small gut infection can end up becoming severe diarrhoea along with blood loss. It is essential to understand the severity of manifestations of diseases varies according to the number of microbes present in the body.

If the number of microbes present in the body is small then the disease manifestation is usually insignificant or minor. If the number of microbes is more, the disease can become severe and life-threatening. The immune system plays a major role in the determination of microbes surviving in the body.

Solved Question for You

Question: Define Immunity

Solution: The Repair Mechanism of the body is known as Immunity.

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6 responses to “Health and Its Significance”

  1. Abhishek says:

    Thanks for the post.best article

  2. Hemoglobin says:

    Fantastic article, Thank you

  3. Grace says:

    I wish they would add the authors, I want to add them to my references.

  4. Andrew D. says:

    These teachers are really teaching well online and thanks for the information on the importance of health.

  5. Nice Article…Keep Writing and update us.

  6. Thank you for the good information

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