PREVENTION AND CONTROL OF DISEASES

Maintenance of hygiene is very important for prevention and control of diseases. Measures for hygiene include keeping the body clean; consumption of clean drinking water, food, vegetables, fruits, proper disposal of waste and excreta; periodic cleaning and disinfection of water reservoirs, pools, cesspools and tanks.

In case of air borne diseases, close contact with the infected person and his belongings should be avoided.

For vector borne diseases such as malaria and filariasis, the measures to control diseases are-

• Control or eliminate the vectors and their breeding places.
• Avoiding stagnation of water in and around residential areas.
• Regular cleaning of household coolers.
• Use of mosquito nets.
• Introducing fishes like Gambusiain ponds that feed on mosquito larvae.
• Spraying of insecticides in ditches, drainage areas and swamps, etc. Mosquito
• Doors and windows should be provided with wire mesh to prevent the entry of mosquitoes.

The use of vaccines and immunization programmes has enabled to control diseases like smallpox, diphtheria, polio, pneumonia, tetanus etc.

IMMUNITY

The overall ability of the body to fight against disease causing microorganisms with the help of immune system is called immunity.

Immunity is two types-

1. Innate immunity
2. Acquired immunity

Innate immunity

The immunity which occurs by birth is called innate immunity.
Innate immunity is non-specific type of defense.
Innate immunity consists of various barriers which prevent the entry of microorganisms into the body.

Innate immunity consists of four types of barriers.

➤ Physical barriers-Skin on our body is the main barrier which prevents entry of the micro-organisms and mucus coating of the epithelium lining the respiratory, gastrointestinal and urogenital tracts also help in trapping microbes entering our body.
➤Physiological barriers- Acid in the stomach, saliva in the mouth, tears from eyes-all prevent microbial growth.
➤ Cellular barriers – Certain types of leukocytes (WBC) of our body like polymorpho-nuclear leukocytes (PMNL- neutrophils), monocytes and natural killer (type of lymphocytes) in the blood as well as macrophages in tissues can phagocytose and destroy microbes.
➤ Cytokine barriers– Virus-infected cells secrete proteins calledinterferons which protect non-infected cells from further viral infection.

Acquired immunity

The immunity which develops during lifetime by exposure to suitable foreign agents like microorganisms is called acquired immunity.
Acquired immunity is pathogen specific and it is characterized by memory.
When the body first encounters a pathogen it produces a response which takes long time to develop and of low intensity called as primary immune response and if the body encounters the same pathogen it produces highly intensified and quick response called as secondary immune response.
After responding to the foreign microorganisms and elimination of the pathogen, the immune system keeps the memory of the that encounter (primary response) and during its second encounter with the same pathogen produces a highly intensified immune response (secondary response).

Memory The primary and secondary immune responses are carried out with the help of two special types of lymphocytes present in our blood.

B-lymphocytes : The B-lymphocytes produce an army of proteins in response to pathogens into our blood to fight with them called as antibodies.

T-lymphocytes: The T-cells themselves do not produce antibodies but help B cells to produce them

STRUCTURE OF ANTIBODY

Each antibody molecule has four peptide chains, two long chains and two short chains arranged in a Y shaped structure. Two long chains are called heavy chains and two short chains are called light chains, hence an antibody is represented as H2L2. Antibodies are also called as immunoglobulins (Ig).

Different types of antibodies are produced in our bodies which are IgA, IgM, IgE, IgG.