Why Do We Fall Ill

Chapter-13 Why Do We Fall Ill Anything that prevents proper functioning of cells and tissues will lead to a lack of proper activity of the body. When a person experiences such a condition, he is said to be ‘ill’ or ‘in poor health’.

What is health? • A state of ‘being well’ • A state of being well enough to function well physically, mentally and socially. Which are the factors important for staying in good health? • • • • • • •

Physical Environment Social Environment Cleanliness (Personal Hygiene and Public Cleanliness) Good Food Good economic conditions Social Equality and harmony (an example of how community issues effect individual health) To have the opportunity to realise the unique potential in all of us

Disease

=

Dis Ease = Disturbed Ease

and there is a specific cause for this

discomfort. Disease is any harmful change that interferes with the normal appearance, structure, or function of the body or any of its parts. Conditions essential for being free of a disease • There should be no discomfort to the individual. • There should be no specific and particular cause for a discomfort Difference between being ‘healthy’ and ‘disease free’ • • •

It is possible to be in poor health without actually suffering from a disease When we think about health, we think about societies and communities When we think about disease, we think about individual sufferers

To identify a disease, we look for signs and symptoms. Symptoms are

•

Unfavorable change in the functioning or appearance of one or more systems of the body.

Signs – things we feel as being “wrong”. • Symptoms give an indication of the disease. Example: Headache, cough, fever, loose motions, pus in the wound etc are symptoms •

Laboratory tests are done to confirm the presence and type of disease. Types of Diseases (based on Duration) Eg. Common Cold

Acute Diseases

Chronic Diseases

An Acute disease does not cause major effects on general health

A Chronic disease will cause major effects on general health(Loss of weight, feeling tired all the time, being short of breath) A chronic disease may affect a person for years

An acute disease may affect a person for a few days or weeks An acute disease will not cause drastic long term affects on the health of a person.

Eg. Elephantiasis

A Chronic disease will cause drastic long term affects on the health of a person. (Prolonged general poor health)

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Causes of Diseases (These are just examples and are not to be generalized for every disease.) Immediate Causes  Infection by Microorganisms (Pathogens=Disease causing organisms)

First Level Cause Infection by Microorganisms

• •

• •

Contributory Causes 

 

Lack of nourishment Economic Status of the Household Genetic Factors

Second Level Cause Lack of Good nourishment

Infectious causes are external causes Eg. Infectious agents like microbes Microbes can spread in the community and infect others Lead to Infectious Diseases

Third Level Cause Poverty and lack of public services

•

Non infectious Causes are internal causes Eg. Some cancers are caused by genetic

•

Cannot infect others

•

Lead to Non-Infectious Diseases

•

abnormalities

Control of the disease depends on • the type of Disease • the immediate causes • are they infectious or non infectious Infectious diseases are caused by Infectious Agents i.e. the microorganisms. Name of the Disease

Caused by (Infectious Agents)

Common Cold, Influenza, Dengue, AIDS

VIRUSES

Typhoid fever, Anthrax, Tuberculosis, Cholera Common Skin Infections like Ringworm

BACTERIA

Malaria, Kala-azar Some intestinal Infections, Elephantiasis

Protozoans DIFFERENT SPECIES OF WORMS

FUNGI

Special Biological Characteristics Live inside host cells Multiply very quickly Live inside host cells Multiply very quickly Live inside host cells Multiply very quickly Multiply very quickly Multiply slowly

Other Examples: • Staphylococci, a bacteria causes acne on skin • Trypanosoma, a protozoan causes Sleeping Sickness. • Leishmania, a protozoan causes Kala-azar. Controlling the Infectious Agents: • •

Closely related groups have similar life processes. Therefore , drugs that block one of these life processes in one member of the group is likely to be effective against other members of the group.

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•

However , the same drug may not work against a microbe belonging to a different group.

What are Antibiotics? Antibiotics (Greek anti, “against”; bios, “life”) are chemical compounds used to kill or inhibit the growth of infectious organisms. • • • • •

Commonly block biochemical pathways important for the growth of bacteria. Example- An antibiotic – Penicillin blocks the bacterial processes that build cell wall. If human beings take Penicillin, it will not effect humans as human cells do not have cell walls. therefore antibiotics will control a number of bacterial infections. Antibiotics do not work against viral infections as viruses do not have the same biochemical processes as bacteria. That is why an antibiotic does not control viral infections like common cold.

Spread of Infectious Diseases/How they can be communicated? Since the infectious agents(microbes can move from an affected person to a healthy person, therefore these diseases are also called Communicable Diseases. Medium for spread of the disease

Process of spread of the disease

Names of Diseases that can be spread this way Common Cold, Pneumonia, Tuberculosis. Cholera

Air (Airborne Diseases) Water (Waterborne Diseases)

•

When an infected person sneezes or coughs, little droplets are thrown out by him.

•

When the excreta from someone suffering from an infectious disease of digestive system, such as Cholera gets mixed with drinking water, and this water is used by a healthy person.

Sexual Act (Sexually Transmitted Diseases) Animals (Eg. Mosquitoes and dogs)

• •

Sexually transmitted Disease Not spread by casual physical contact like handshakes, hugs etc.

AIDS, Syphilis

•

These animals are called VECTORS or INTERMEDIARIES Carry infecting agent from a sick person to a potential host.

Malaria, Rabies

•

How does the AIDS virus spread from a healthy person to a diseased person? 1. Sexual Contact, 2. Blood to Blood contact with infected people, 3. Infected mother to her baby during pregnancy, 4. Infected mother to her baby through breast feeding.

Why do the female mosquitoes of a species, suck blood from warm blooded animals like human beings? Because the female mosquitoes need highly nutritious food in the form of blood, in order to lay mature eggs.

Manifestation of the Disease(In what ways does the disease affects a person) How does the microbe enter the body

Through air via

Organ/ tissue likely to be targeted by the microorganism

Lungs

Symptoms of the Disease

Sneezing , coughing

Examples of Diseases

Tuberculosis 3

nose Through Mouth By Mosquitoes

Gut Lining or Liver Liver, Red Blood Cells

Diarrhea etc. Shivering, fever, Jaundice

Typhoid,Jaundice Malaria

By Mosquitoes

Brain

Headache, fever, vomiting, fits, unconsciousness

Japanese Encephalitis

The above table shows some specific effects. There are COMMON EFFECTS too.

The body’s immune system is activated in response to an infection. An active immune system will send to the affected tissue to kill the pathogens. This causes inflammation. Local effects of inflammation=swelling and pain General Effects of inflammation=fever

Severity of the Disease system

depends on

Symptom Directed Treatment ie to reduce the effects of the disease. Medicines to bring down fever, to reduce pain and for loose motions. Bed rest to conserve energy.

no. of microbes in the body

Principle s of Treatme

depends on

the immune

Treatment that aims at killing the diseasecausing microbe Usually medicines are used to kill the microbes. The biochemical pathways used by these microbes can be disturbed/blocked.However , care should be taken that these medicines should not effect biochemical pathways important for our body. Eg. Antibiotics, drugs that kill protozoans, anti viral drugs etc.

Limitations to Principles of treatment for infectious diseases: 1) The body functions may be damaged due to the disease and the patient may never recover completely. 2) Treatment takes time and may cast a lot of money. 3) the infection may spread to other people. THAT IS WHY PREVENTION OF DISEASES IS BETTER THAN THEIR CURE Principles of Prevention

Two types of methods: a) General Methods b) Methods Specific to a

disease General Methods of prevention: Prevent exposure and availability of proper and sufficient food to build a strong immune system. How to prevent exposure: Type of Disease/Microbe How to prevent exposure AirBorne By providing living conditions that are not overcrowded. WaterBorne By providing safe drinking water, treating water to kill microbial contamination Vector Borne Clean environment that does not allows mosquitoes to breed-Public Hygiene 4

Specific Methods of prevention-are disease specific Immunisation ie Vaccination by which we can fool the immune system into developing antibodies against a disease.By this method the body builds up ‘strength’ to fight against a disease. Questions: 1) Why is it difficult to make antiviral medicines? 2) What is HIV-AIDS? How does this disease spread from one person to another? List the symptoms of this disease. What are its general effects? How does a person suffering from AIDS die? 3) How was small pox eradicated? 4) Why are children living in many parts of India usually immune to Hepatitis –A? 5) Name five disease against which vaccines are available. 6) Comment on the following statement: ‘ Having a disease means preventing subsequent attacks of the same”

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