Quiz 21: Animal Health
Disease is defined as deviation from the normal health resulted due to changes in physiological, anatomical or chemical systems of the body. The diseases are two types called noninfectious and infectious diseases. Noninfectious diseases are produced to injury, genetic abnormalities, consumption of toxic materials and poor nutrition. Any microorganisms or pathogen is not involved in noninfectious diseases. The plant poisoning, bloat and mineral deficiencies in animals are the noninfectious diseases. Infectious diseases involve microorganisms or pathogens like bacteria, viruses and protozoa. Infectious disease can be a contagious disease because it spreads one animal to another rapidly. Infectious diseases include Trichomoniasis, ring worm and transmissible gastroenteritis (TGE) etc.
Immunity is the process by which a foreign particle is detected by the body and is destroyed or metabolized subsequently. The resistance to infections is toxins is gained by highly active immune system. The immune system efficiency is not in a fixed state but varies with the age of the animal, nutritional status and degree of exposure to pathogens. Immunity is of two types called natural or native immunity and acquired resistance. The natural or native immunity occurs from the birth under normal conditions. For example, the skin, secretions of respiratory and intestinal tracts trap the microorganisms. The acidic environment of stomach protects the animals from disease and is therefore called the native immunity. Acquired resistance in animals is provided by the specialized and activated white blood cells known as lymphocytes. These cells are produced by lymphoid organs like spleen, lymph nodes, intestines, and mammary glands, respiratory and reproductive tracts. The acquired immunity is activated when the foreign substance or antigen enters the body.
The lymphocytes are of two types known as B cells and T cells. The B cells produce antibodies in response to antigens that are specifically transferred through body fluids. Therefore, the antibodies provide humoral immunity that detect the free pathogens and are neutralized. The T cells provide intracellular protection by stimulating production of some substances that directly attack the infected cells. The T cells activate the cell mediated immunity that is effective against virus infected cells, intracellular bacteria and cancer. Macrophages are produced as a cell mediated response to engulf foreign bodies, dead and damaged cells to destroy them by enzymatic action. Antigens are the foreign substances that activate the acquired immunity when they enter the body.
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