Why do we fall ill
1) The severity of a disease is directly proportional to the number of infectious agents present in body.
2) An infectious disease can be treated in 2 ways:
i) Reduce the symptoms of the disease by providing treatment
ii) Kill the infectious agent causing the disease.
33) Medicines used in killing an infectious agent aim to disrupt some pathway of a vital life function peculiar to that group of organisms. These pathways are not present in other microbial groups or in humans.
34) On entering human cells, viruses use our cellular machinery for carrying out all their life processes. There are very few virus-specific biochemical pathways that can be targeted to produce anti-viral drugs.
35) The approach of treatment of an infectious disease has three drawbacks:
i) Recovery of the patient may not be complete in certain cases.
ii) Treatment requires time; hence the patient suffers from the disease and may be bedridden.
iii) The patient serves as the source of spread of infection to others.
36) It is desirable to prevent a disease than to treat it completely.
37) There are general and specific ways of preventing diseases.
38) Infectious diseases can be generally prevented by public health hygiene methods, which aim to reduce exposure to infectious microbes. Public hygiene measures include providing safe drinking water, clean environments and adequately spacious conditions for living.
39) Another general method of preventing infectious diseases requires the availability of sufficient and balanced diet for the proper functioning of the immune system. The immune system ensures that we do not develop a disease each time we are exposed to an infectious agent, by destroying the agent before it multiplies greatly.
40) During smallpox epidemics, it was noted that people who survived after suffering form smallpox, did not get infected with it again. Such observations led to the birth of immunization, which is a specific method of preventing infectious diseases.
41) The principle of immunization is based on the memory of the immune system on encountering an infectious agent. On subsequent encounters with the same or related microbe, the response of the immune system is multiplied greatly, leading to quick elimination of the infection.
42) During immunization, a vaccine (containing weakened or killed pathogen or a specific part of the pathogen) is introduced into the body to fool the immune system into remembering a particular infection. Hence the body does not suffer even on further exposures to that pathogen or its close relatives.
43) Nowadays, vaccines preventing many infectious diseases like tetanus, polio and measles are used extensively especially in child health immunization programmes.
44) Everyone in the community should have access to public hygiene and immunization for effective prevention of infectious diseases.
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NCERT 9 Science