Why Do We Fall Ill?

-Apoorva Doshi -Apoorva Doshi

• Health is a state of physical, mental and social well-being.

• Disease – Any disturbance in the structure and /or function of any organ or part of body.

Factors on which health depends

• Physical and Social environment• Public facilities /Public cleanliness• Good economic conditions/ good jobs• Social equality and Harmony• Most important :- personal Hygeine

Distinction between healthy and disease-free

Healthy

1. It is a state of physical, mental and social well-being.

2. It refers not only to the individual but also its social and community environment

3. A ‘healthy’ person is able to perform normal under given situation.

4. For e.g. being able to do graceful positions while dancing.(for a dancer)

Disease-free

1. It is a state of absence of any kind discomfort or derangement of functioning of body.

2. It refers to individual.

3. A disease free person may or may not be healthy.

4. For e.g. free of disease but not able to stretch body properly while dancing.(for a dancer)

What does a disease look like ?

• When there is a disease, the functioning of 1 or more body systems will change for worse.

• These changes give rise to symptoms.• Symptoms of a disease are things that we feel are

wrong. They don’t tell what us which disease we are suffering from but just indicate that we may be “diseased”.

• For example :- a headache may mean just examination stress and in very rare case a disease.

• Whereas Signs are what physicians/doctors look for on the basis of symptoms. They will give a more definite indication of presence of a disease.

• Physicians may get laboratory tests to pinpoint the disease further.

TYPES OF DISEASES

• Acute disease – Some diseases last for only very short periods of time, and these are called acute diseases.

E.g. common cold

• Chronic diseases :- The diseases which last for a long time , sometimes for even a lifetime , are known as chronic diseases.

• For e.g. Tuberculosis, elephantiasis ,etc.

• Congenital disease – The diseases that are present since birth. They are caused due to genetic abnormalities / due to metabolic disorder / malfunctioning of organ. They are permanent, generally not easily curable & may be inherited to children.

• For example :- Congenital blindness, congenital deafness, etc.

• Acquired diseases –The diseases which are developed after birth.

• For example :- Myopia, Hypermetropia ,etc.

Acquired diseases – Which develop after birth

• Infectious disease –The diseases that are communicated from diseased person to healthy person. Caused by some biological agents / pathogens like – Viruses, bacteria, protozoan, nematodes, fungi

• Non-infectious disease – the diseases that are restricted only to those persons who are suffering. Diseases that are not caused by infectious agents. Otherwise, diseases that ARE CAUSED FROM “INTERIOR“ OF THE BODY. For example :- High blood pressure, “genetic” cancer ,etc.

Comparison of damages to health by acute & chronic diseases

• Common cold • Tuberculosis

Damages done by acute diseases

• Little bit tiredness• Small headache

All this are very short term damages done and don’t have any effect on long term life.

Damages done by chronic diseases

• Long term weakness .• Feeling tired 24x7.• Becoming short of breadth.• Losing excessive weight.• Prolonged general poor health.• Breathing problems.(rare)

These all happen because of being “long-term” sick.

Causes of a disease

• Each disease has immediate as well as contributory causes. They are known as levels of causes.

• For example:-If a baby is suffering from loose motions it is clear that he has been infected with a virus. This is the first level cause/immediate cause. But where does the virus came from?

• If it came from water then why only he is infected not other babies? May be his not healthy because he doesn't enough nutrition OR he may have any genetic impairment that makes him more prone to the disease than other babies of his age. So this becomes the second level of cause/ contributory cause.

Infectious and Non-infectious causes

• Immediate causes belong to two types:-– Infectious Causes (microbes)– Non-Infectious causes(genetic abnormalities, etc.)

Infectious Causes

Non-Infectious causes

Infectious agents - Organisms that can cause disease are found in a wide range of such categories of classification.

• Some of them are viruses, some are bacteria, some are fungi, some are single-celled animals or protozoans. Some diseases are also caused by multicellular organisms, such as worms of different kinds.

Infectious agent Disease

Virus Common cold, influenza, dengue fever, AIDS

Bacteria Typhoid fever, cholera, tuberculosis, anthrax

Fungi Many common infectious disease

Protozoan Malaria, kala azar

Worms worm infections, elephantiasis

Why is it important that we think of these categories of infectious agents?

• These categories are important factors in deciding what kind of treatment to use. Members of each one of these groups – viruses, bacteria, and so on – have many biological characteristics in common.

• All viruses, for example, live inside host cells, whereas bacteria very rarely do.

• Viruses ,bacteria and fungi multiply very quickly, while worms multiply very slowly in comparison.

• Taxonomically, all bacteria are closely related to each other than to viruses and vice versa.

Why is it important that we think of these categories of infectious agents?

• This means that many important life processes are similar in the bacteria group but are not shared with the virus group. As a result, drugs that block one of these life processes in one member of the group is likely to be effective against many other members of the group. But the same drug will not work against a microbe belonging to a different group.

As an example, let us take antibiotics.

• They commonly block biochemical pathways important for bacteria. Many bacteria, For example, make a cell-wall to protect themselves. The antibiotic penicillin blocks the bacterial processes that build the cell wall. As a result, the growing bacteria become unable to make cell-walls, and die easily.

• Human cells don’t make a cell-wall any way, so penicillin cannot have such an effect on us. Penicillin will have this effect on any bacteria that use such processes for making cell-walls. Similarly, many antibiotics work against many species of bacteria rather than simply working against one.

• But viruses do not use these pathways at all, and that is the reason why antibiotics do not work against viral infections. If we have a common cold, taking antibiotics does not reduce the severity or the duration of the disease. However, if we also get a bacterial infection along with the viral cold, taking antibiotics will help. Even then, the antibiotic will work only against the bacterial part of the infection, not the viral infection.

Means of spread of infectious disease

1. Air borne diseases Common cold, pneumonia, tuberculosis

2. Water borne diseases

Cholera, amoeboisis

3. Sexually transmitted diseases

Syphilis, AIDS

4. Through vectors Anopheles mosquitoes – vector of malaria

Organ specific & tissue specific Manifestations(After entry of microbes in our body where do they go?)

Answer depends on Point of entry

• e.g. tuberculosis - caused by bacteria - entry point through Nose to lungs

• e.g. typhoid – caused by bacteria through - Mouth to Guts

• e.g. jaundice – caused by viruses – through mouth to liver

• Sex organs – lymph nodes – e.g. virus – AIDS

• e.g. Japanese encephalitis (brain fever) – virus- enter through a mosquito bite infect the brain.

Principles of treatment :-

• The treatment of infectious diseases consists of two steps. They are to reduce the effects of the disease (symptoms) and to kill the microbes which caused the disease.

1. To reduce the effects of the disease :- This can be done by taking medicines to bring down the effects of the disease like fever, pain or loose motions etc. and by taking bed rest to conserve our energy.

2. To kill the microbes :- This can be done by taking suitable antibiotics and drugs which kills the microbes and the disease is cured.

Principles of prevention :-• There are two ways of prevention of infectious

diseases. They are general ways and specific ways.

• i) General ways of prevention :-• Public hygiene is most important for prevention of

infectious diseases. Proper and sufficient food for every one will make people healthy to resist infection.

• Air borne diseases can be prevented by living in conditions that are not crowded. Water borne diseases can be prevented by providing safe drinking water. Vector borne diseases can be prevented by providing clean environment.

ii)Specific ways of Prevention

• The specific ways to prevent infectious disease is immunization by taking vaccines. Vaccines provide immunity from infectious diseases like tetanus, diphtheria, whooping cough, measles, polio etc.

• Our body has an immune system which fights microbial infection. When this system first sees an infectious microbe, it kills the microbe and remembers it. So if the microbe enters the body the next time, it responds more vigorously. Vaccines mimic the infectious microbe and strengthens our immune system and protects the body from infectious diseases.

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