Preksha Dhyana Human Body Part 2

Author(s): Jethalal S Zaveri
Publisher: Jain Vishva Bharati

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After the germ has gained access into the body by one means or another, an incubation period follows. During this time, bacteria multiply without any outward sign of infection. After a period that varies from a few hours to a matter of weeks or months, depending on the disease, the numbers of the pathogens are so great that the normal life-processes of the host are disturbed and symptoms of disease become manifest. Pitched battles are carried on within the body between the body-defences and the invaders.
The harm caused by pathogenic germ is usually produced by poisons manufactured by them. These are of two types : exotoxins and endotoxins. Exotoxins diffuse out from the bacterial cell into the tissues of the host organism. These are proteins and are powerful poisons. Those of tetanus, for example, are far more powerful than any snake venom. Endotoxins are produced within the bacterial cell and are released when the cell disintegrates. They are less poisonous than exotoxins. Bacteria of typhoid (fever) produce endotoxins. Generally bacteria produce either exotoxins or endotoxins, but not both.
Viral Diseases
Viruses are micro-organisms. Some pathogenic viruses are so tiny that they cannot be seen with the most powerful optical microscope and pass through a filter, fine enough to trap the smallest bacteria. They are so rudimentary that many scientists do not consider them to be truly alive. They lie at the very borderline of life. Viruses can reproduce only within a living host.
Many diseases including poliomyelitis, influenza, measles, yellow fever and the common cold are traced to viruses. Virus-caused disease can be prevented by vaccines, in which the genetically changed attenuated virus has lost most of its virulence but still retains enough similarity to the original form to produce immunity to the original disease.
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