Chapter-13 Why Do We Fall Ill Anything that prevents proper functioning of cells and tissues will lead to a proper lack of proper activity of the body. When a person experiences such a condition, he is said to be ‘ill’ or ‘in poor po or health’. health’. What is health? A state of ‘being well’
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A state of being well enough to function well physically, mentally and socially.
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Which are the factors important for staying in good health? Physical Environment
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Social Environment
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Cleanliness (Personal Hygiene and Public Cleanliness)
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Good Food
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Good economic conditions
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Social Equality and harmony (an example of how community issues effect individual health)
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To have the opportunity to realise the unique potential in all of us
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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.
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There should be no specific and particular cause for for a discomfort
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Difference between being ‘healthy’ and ‘disease free’ It is possible to be in poor health without actually suffering from a disease
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When we think about health, we think about societies and communities
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When we think about disease, we think about individual sufferers
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To identify a disease, we look for signs and symptoms. Symptoms are Unfavorable Unfavorable change in the functioning or appearance of one or more systems of the body.
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Signs – things we feel as being “wrong”. “wrong”.
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Symptoms give an indication of the disease.
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Example: Headache, cough, fever, fever, loose motions, pus in the wound etc are symptoms sy mptoms Laboratory tests are done to confirm confir m the presence and type of disease.
Types of Diseases (based on Duration)
Acute Diseases Eg. Common Cold ●
An Acute disease does not cause major effects on general health
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An acute disease may affect a person for a few days or weeks
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An acute disease will not cause drastic long term affects on the health of a person.
Chronic Diseases Eg. Elephantiasis ●
A Chronic disease will cause major effects on general health(Loss of weight, feeling tired all the time, being short of breath)
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A chronic disease may affect a person for years
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A Chronic disease will cause drastic long term affects on the health of a person.
(Prolonged general poor health)
Causes of Diseases (These are just examples and are not to be generalized for every disease.) Immediate Causes ●
Contributory Causes
Infection by Microorganisms
(Pathogens=Disease (Pathogens=Disease causing organisms)
First Level Cause Infection by Microorganisms
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Lack of nourishment
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Economic Status of the Household
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Genetic Factors
Second Level Cause Lack of Good nourishment
Third Level Cause Poverty and lack of public services
Infectious causes
Non infectious Causes
are usually external causes
are usually internal causes
Eg. Infectious agents like microbes
Eg. Some cancers are caused by genetic abnormalities
Microbes can spread in the community and infect others
Cannot infect others
Lead to Infectious Diseases
Lead to Non-Infectious Diseases
Control of the disease depends on
the type of Disease
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the immediate causes
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are they infectious or non infectious
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Infectious diseases are caused by Infectious Agents i.e. the microorganisms.
Name of the Disease Common Cold, Influenza, Dengue, AIDS
Caused by (Infectious Agents) VIRUSES
Special Biological Characteristics Live inside host cells Multiply very quickly
Typhoid fever, Anthrax, Tuberculosis, Cholera
BACTERIA
Live inside host cells Multiply very quickly
Common Skin Infections like Ringworm
FUNGI
Live inside host cells Multiply very quickly
Malaria, Kala-azar
Protozoans
Multiply very quickly
Some intestinal Infections, Elephantiasis
DIFFERENT SPECIES OF WORMS
Multiply slowly
Other Examples:
Staphylococci , a bacteria causes acne on skin
Trypanosoma , a protozoan causes Sleeping Sickness.
Leishmania , a protozoan causes Kala-azar. Kala-azar.
Controlling the Infectious Agents: Closely related groups have similar life processes.
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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.
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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.
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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.
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therefore antibiotics will control a number of bacterial infections.
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Antibiotics do not work against viral infections as viruses do not have h ave the same biochemical processes as bacteria. •
That is why an antibiotic does not control viral infections like common cold.
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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
Air (Airborne Diseases)
Water (Waterborne Diseases)
Process of spread of the disease
When an infected person sneezes or coughs, little droplets are thrown out by him.
Common Cold, Pneumonia, Tuberculosis.
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.
Cholera
Sexually transmitted Disease
Sexual Act (Sexually Transmitted Diseases)
Not spread by casual physical contact like handshakes, hugs etc.
Animals
These animals are called VECTORS or INTERMEDIARIES
(Eg. Mosquitoes and dogs)
Names of Diseases that can be spread this way
AIDS, Syphilis
Malaria, Rabies
Carry infecting agent from a sick person to a potential host.
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, 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
Organ/ tissue likely to be targeted by the microorganism
Symp Sympto toms ms of the the Dis Disea ease se
Through air via nose
Lungs
Sneezing , coughing
Tuberculosis
Through Mouth
Gut Lining or Liver
Diarrhea etc.
Typhoid,Jaundice
By Mosq Mosqui uittoes oes
Liv Liver, er, Red Bloo Blood d Ce Cell llss Sh Shiv iver erin ing, g, feve feverr, Jau aund ndic ice e Mala Malari ria a
By Mosquitoes
Brain
Headache, fever, vomiting, fits, unconsciousness
The above table shows some specific effects.
Exam Exampl ples es of of Dise Disease ases s
Japanese Encephalitis
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
Limitations to Principles of treatment for infectious diseases: 1) The body functions may be damaged due to the disease and the th e patient may never recover completely. completely. 2) Treatment takes time and may cast a lot of money. 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 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
Air Borne
How to prevent exposure By providing living conditions that are not overcrowded.
Water Borne
By providing safe drinking water, treating water to kill microbial contamination
Vector Borne
Clean environment that does not allows mosquitoes to breedPublic Hygiene
Specific Methods of prevention-are disease specific Immunization 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. available. 6) Comment on the following statement: ‘ Having a disease means preventing subsequent attacks of the same”
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