Why do we fall ill?

Health: State of complete physical, social and mental well being and not only the absence of diseases.

Personal and community health:

           Personal health is directly linked to community health. Health of a person influenced by the environment and community. Community health involves

i) Provision of safe and clean drinking water

ii) Health care facilities

iii) Health education and IV) provision for sanitation

Diseases: Any deviation from normal body functioning resulting in disturbed state or stare of discomfort.

Indication of diseases:

Symptoms: General visible changes in the body during the diseased state include fever, headache, vomiting general weakness etc. they don’t point towards specific diseases. Signs- specific indications which point towards a specific diseases. E.g. specific fever pattern in malarias, rashes on skin in chicken pox etc. on the basis of signs doctor performs diagnostic tests and confirms the diseases.

  The signs and symptoms of the disease depend upon tissue or organs, the infectious agent or microbe agent.

               

TISSUE SPECIFIC MANIFESTATIONS-
Organ or tissue target                     Tissues specific symptoms            

1.     Lungs                                            Cough, breathless

2.     Liver                                             Yellowing of body ,digestion problems(jaundice)

3.     Brain                                             Headache, vomiting, fits     

4.     Intestine                                        Diarrhea

Classification of diseases:

·         On the basis of duration  : Acute & chronic

·         On the basis of  infection: communicable & non- communicable

 Acute                                                                 Chronic

1.      Last for short duration.                                1. Last for long duration.

                                                                                        (May be months or years) 

    2.  Do not affect general health for                     2. General health is affected badly.

          a long time.  

    3.  Vital organs of body are not affected.           3. Vital organs are affected.

E.g. influenza, malaria                                         E.g. leprosy, T.B

Communicable                                               Non communicable

1. Spread from diseases to healthy person.      1. Do not spread.

2. Spread by means of air water food,              2. Do not spread by these means.

     insects bite etc.

3. Caused by microbes.                                    3. Caused by genetic disorder   metabolic problems, food deficiency, pollution etc.

e.g.  T.B, chickenpox                                            e.g.  Marasmus, hemophilia

Causes and spread:

Causes or factor are of two types:

1.   External (extrinsic)causes or factors

                    I.            Diseases causing microorganisms commonly called pathogens

                  II.            Inadequate diet

                III.            Environmental pollutants

                IV.            Tobacco, alcohol and narcotic drugs

2.   Internal (intrinsic) causes or factors.

                    I.            Malfunctioning or improper functioning of body parts

                  II.            Genetic disorders

                III.            Hypo or hyper secretion of hormones

                IV.            Malfunctioning of body’s immune system

                      Level of caused – first level – refers to immediate cause of causative organisms of diseases (virus, bacteria).etc.

  

                                                       Second level- why the infection occurred to that     

                                                       Person (whether the person is weak has insured

                                                   Inhibitory cause                         something wrong or has genetic problems etc.

                                                                       Third level- deals with public health and public services           

                                                                       That a person is exposed to e.g. whether the

                                                                       Surrounding is clean there is provision of safe water.

Causes of infectious diseases:

  Virus –influenza, Dengue, AIDS

Bacteria – typhoid, cholera. T.B, anthrax

Fungi- skin infectious, athletics foot

Protozoa- malaria, worms- elephantiasis

      Category of microbe is important to know as it helps in deciding the kind of treatment.

·         Virus lives inside host cell. Bacteria rarely.

·         Worms multiply slowly. The others very fast.

·         Bacteria are closely related to each other and not to viruses or other categories.

·          

Mode of spread:

·         Direct contact: by touching using attires of diseased e.g. chicken pox.

·         Airborne or droplet infection: for the diseases that spread through air tiny droplets containing microbes are released in air when the infected person cough or sneezes. When a healthy person inhales these droplets he can also suffer from the disease. This is called droplet infection e.g. pneumonia, T.B, common cold.

·         Food and water: contaminated water and food containing microbes which may enter water source through secretions (vomiting, excreta) of diseased may act as source of infection. E.g. jaundice , hepatitis , cholera

·         Sexual contact- e.g.- AIDS, Syphilis

·         Insect – insects may act as vectors / carrier of diseases

    Distinctions between healthy and disease- free

Healthy	Diseases-free
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 ‘individual is one who is able to perform normal under given situation.	.       1.It is a state of absence of any discomfort or derangement of the functioning of the body. .         2. .It refers to the individual.         3.. A ‘disease-free’ individual may have good health or poor health.

                                                                                                                                         

Vector	Carrier
1.      Carries specific germs inside its body. 2.      Caused agent needs vector to complete its life cycle. E.g. female anopheles is a vector of plasmodium that causes malaria.	1.      Carries many germs upon its surface (wings, legs, etc.) 2.      Caused agent doesn’t need carriers to complete its life cycle. e.g. housefly is a carrier of many germs or diseases like cholera , typhoid etc.

     

Effects of diseases

Microbes enter the body through different body parts. The specific part affected depends upon the point of entry of microbe. (ORGAN SPECIFIC MANIFESTATIONS)

  Point of entry                   organ likely to be infected             Example

• ·            Nose                                      lungs and lymph nodes                         T.B
• ·          Mouth                                   alimentary canal , liver                    Japanese enuphatitis
• ·          Blood                                    Brain , liver cells, RBC                        Malaria
•       (Through mosquito
•         bite)
• 
  
•         Reproductive organs             reproductive organs                             Syphilis
•         (Sexual contact)                      immune system                                     AIDS

Common effect of diseases:

When infectious occurs in body immune system gets activated which results in a series of effects, together constituting inflammation.

Inflammation: the immediate response of the body towards an infection/ injury is called inflammation. Due to activation of immune system, there is increased blood supply in the affected area so that WBC can reach the place of infection and kill germs. This results in swelling and itching. These are the local effects produced during inflammation. While fever occurs as a general effect in body. (Hence mild fever is a protective mechanism. High fever destroys thermo-regulation.

  Treatment

Occurrence of diseases depends upon:

1.      Number of germs that enter body

2.      Whether the germs are virulent(strong)

3.      Strength of body’s immune system.

These are treatment of diseases

1.      Reduce the effect of diseases(Analgesics, Antipyretic , bed rest)

2.      Kill the cause of diseases (antibiotics to kill microbes)

 Antibiotics- medicines made from bacteria and fungi and used against them.

Broad spectrum antibiotics- An antibiotic may be effective against many strains of bacteria because these bacteria have similar biochemical pathways. E.g. penicillin blocks biochemical pathways that build cell wall. Hence bacteria are unable to make cell wall and die.

Q. why are antibiotics ineffective against viruses?

A. viruses do not have metabolic pathways as found in bacteria. Instead viruses make use of machinery and pathways of host cell. Hence antibiotics are not effective against viruses. For viruses, antiviral drugs are used.

Prevention is better than cure:

·      Once a person has a disease some of body functions may get damaged and do not recover treatment of or disease takes time and the person becomes incapable of normal routine.

·         Person may spread the disease to the others.

Prevention of diseases-

General ways-

·         By keeping environment clean

·         Providing clean drinking water ventilation

·         Providing proper, sufficient and clean food and balanced diet.

·         Exercise

Specific ways: by vaccination

Immunity:  ability of body to resist or diseases.

Immunization: method of imparting immunity to a specific disease by way of vaccination.

Principle of vaccination-

·         Dead or weakened germs are infected in body in the forms of vaccine.

·         These germs are not capable of providing a disease. But they act as antigens and body produces antibodies against them.

·         It also generated large number of memory cells which remains in body for long time. when the vaccinations person is attacked by the same pathogen the existing memory cells recognize antigen and produce large number of antibodies to combat the pathogen and the person does not suffer from the diseases.(this kind of immunity is also called active immunity).

(Ready made antibodies are given as vaccine in passive immunity but they are short lived)