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Why Do We Fall Ill??
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Why Do We Fall Ill??


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  • 1. Welcome to the worldWelcome to the world of biologyof biology Why do we fall ill???Why do we fall ill???
  • 2. What is Disease?? • Disease is any condition that may lead to discomfort,distress,health problems, or death of the affected person…….
  • 3. Health and It’s failure • HEALTH is described as the state of complete physical, mental and social well being.Thus,being healthy means that one feels good physically, has a positive outlook and is able to cope with the social and mental pressures without much difficulty .A person should maintain the good hygiene to reduce the chances of developing infection. • A doctor is able to diagnose disease by identifying the symptoms which may be physical. mental or both. • Our health is affected not only by unbalanced diet but also by disease causing organisms which may be water borne, air borne or food borne and some diseases are caused by infection through microorganisms, insects organisms such as bacteria,fungi,protozoas,etc.
  • 4. Diseases • Infectious diseases spread through infectious agents (Virus,Bacteria,other microorganisms).. • An infectious disease is called communicable disease, if it spreads from an infected person to a healthy person.. • Disease caused by non infectious agent (Excessive weight, genetic defects,etc.) are called Non-infectious diseases…. • Non-infectious disease can’t be transferred from a diseases person to a healthy person……
  • 5. Modes of transmission of diseases • Infectious disease(bacteria,fungi,etc.) • Parasites • Contaminated food or water • Blood transmission • Vectors/animals • Direct physical contact
  • 6. Types of diseases DISEASES Congenital Acquired Infectious Non-infectious Contagious Non-contagious Deficiency diseases Metabolic diseases Degenerative cancer diseases Metabolic allergies Injury
  • 7. Definitions of types of diseases (i) Acute diseases-Diseases are described as being acute, when their symptoms are quickly visible in the body. (ii) Chronic diseases- These types of diseases are long-term, with the symptoms lasting for months or years. (iii) Congenital diseases-These diseases are present since birth. They are caused due to genetic abnormalities or due to metabolic disorders or malfunctioning of any organ. (iv) Acquired diseases-These diseases are those which develop after birth. These are classified into two types-(i) communicable ; (ii) non-communicable. (v) Infectious diseases-These diseases are caused by biological agents or pathogens such as virus, bacteria and fungi. These diseases can rapidly spread from one person to another. (vi) Non-infectious diseases-These include organic or metabolic diseases. These diseases are restricted only to those persons who are suffering from them.
  • 8. INFECTIOUS DISEASES I. Infection Agents Organisms that can cause diseases are classified in wide range of categories. Some of them are viruses, some are bacteria, some are fungi and some are unicellular animals, the protozoans.Some diseases are also caused by multicellular organisms such as worms. Common example of diseases caused by viruses are the common cold,influenza,dengue,fever and AIDS and common skin infection caused by different kinds of fungi.Protozoans cause many familiar diseases such as malaria and kala azar.Worms tend to cause a variety of intestinal infections and elephtiasis
  • 9. II.Means of Spread of Infectious Diseases Infectious diseases spread from one infected person to other normal persons by various methods.. 1.Air-borne diseases,e.g., common cold,pneumonia.such disease-causing microbes are spread through out the air.. 2.Water-borne diseases,e.g., cholera.Infectious diseases can also spread through water.These occur when a stool from someone suffering from an infectious gut disease,such as cholera or amebiasis,gets mixed with drinking water used by people nearby.. 3. 3.Sexually-transmitted diseases,e.g.,AIDS.These diseases are transmitted by sexual contact from one partner to the other partner.. 4.Spread of diseases through vectors.Many animals which live around us may carry diseases.These animals can transfer infecting agents from a sick person to another potential host..
  • 10. Example of Diseases Caused to Infection By Microorganisms 1.Malaria Malaria is a fatal disease for human beings. Approximately 300 million people around the world get infected with malaria every year.Malaria is caused by a protozoan parasite Plasmodium.This disease spreads through the bite of an insect vector-the female Anopheles mosquito which feeds on the human blood. Symptoms-1.Cold stage,feeling of extreme cold and shivers ; stage,high fever, faster respiration and heart beat; and 3.sweating stage,due to the profuse sweating,temperature of the body goes down to norrmal.Even after cured of malaria, the patient feels weak and anaemic. Prevention-1.Insect-repellents should be used to prevent mosquito bites. 2.One should keep under mosquito nets. 3.Wire-gauze should be used on doors and windows of houses to prevent entry of mosquitoes. 4.Mosqito larvae can be killed by sprinkling kerosene oil on large-sized water bodies. 5.The breeding grounds should be should be destroyed.Thus,the ditchess,puddles or swamps around human dwellings should be drained or filled. Control-A drug named quinine, which is extracted from the bark of the Cinchona tree,is used to treat a person suffering from malaria.
  • 11. Diseases Caused by Viruses 2.Influenza Influenza is commonly called flu. It is caused by an influenza virus. There exist three types of inflenza viruses-A,B and C. A and B are important because these are responsible for causing of disease epidemics throughout the world. The inhaled virus attacks the epithelial cells in the mucous membrane of nose, throat and upper respiratory tract. Influenza is spread mainly from person to person contact and by droplet infection via sneezing, coughing or talking Symptoms-Onset on chills, discharge from nose,sneezing,fever,headache,muscular pains,coughing,inflammation of respiratory mucosa and general weakness.Fever lasts for three days in adults. Prevention-We should try to keep away from flu patients. Control-There is no effective control of ifluenza.However,vaccines are used for the control of infection and antiviral drugs are used to cure. Rest speeds up the recovery
  • 12. Rabies(Hydrphobia) The bite of a rabid dog(mad dog) and some other such as monkeys,cats or rabbits may cause rabies,which is fatal viral disease cause by rabies virus or lyssa virus which is present in the saliva of infected animals.The viruses are injected into human blood by the bite of rabid animal. Symptoms-Rabies is characterised by serve,headache,high fever,painful contraction of muscles of throat and chest.The patient feels restless,does excessive salivation, has a choking feeling and finds difficulty in take of even liquid. Prevention-1.Cleaning the wound with carbolic soap and clear water immediately after the dog bite is an important preventive measure. 2.Any antiseptic medicine should be applied the wound caused by a dog bite. 3.A rabid animal shows excessive salivation and tries to seek isolation after bite. Such mad animals should be killed. Control-Rabies can be treated with Pasteur’s treatment,in which a course of 14 vaccines was given.Currently 5 anti- rabies vaccines are prescribed at an interval of 0-3-7-14-30 day of dog bite.
  • 13. AIDS The disease of AIDS is caused by retrovirus known as HIV.AIDS virus attacks white blood cells of human beings and weakens the human body’s immunity or self-defense meachanism.Since AIDS virus reduces the natural immunity of the human body,therefore,the patients suffering from AIDS becomes prone to many other infections or diseases.In fact, the patients suffering from AIDS die from other infections. Symptoms-Some important symptoms of AIDS are following: swollen lymph nodes; regular fever;sweating at night and weight loss. AIDS virus causes severe damage to brain and may lead to loss of memory, ability to speak and of clear thinking. Prevention-So far no medicine or vaccine has been developed to cure AIDS. The following steps may help in controlling infection of this dreaded disease: 1.People should be educated about AIDS transmission. 2.Disposable syringes and needles should be used for injection. 3.Sexual contact with unknown people should be avoided. 4.Sterillised needles may be provided to drug addicts. 5.Before receiving blood for transfussion,one should ensure that it has been screened for HIV.
  • 14. Diseases caused by Bacteria Cholera Cholera is an actuely infectious, fatal disease.Sometimes cholera occurs in epidemic form and spread over large population.Cholera is caused by the bacterium, Vibrio cholerae.It is transmitted by flies,contaminated food and water.When the bacteria f cholera is ingested,they multiply in the small intestine and invade its epithelial cells.When the bacteria die,they release toxins which irritate the intestinal lining and lead to the secretion of large amounts of water and salts. Symptoms-1.Watery diarrhea which is generally painless. 2.Efforts vomiting without nausea. 3.Loss of several liters of liquid from the patient’s body takes place within hours. Prevention-1.Person should be immunised by standard cholera vaccine 2.Careful personal hygiene and good sanitation in the community are the only certain protection against cholera. 3.In cholera-prone areas, boiled water and cooked should be taken
  • 15. TyphoidTyphoid is the most common communicable disease in India. It is common in humans of the 1 to 15 years age group. Typhoid is cause by a rod-shaped and motile bacterium, called Salmonella typhi which is found in the intestine of intestine of human beings.Infection takes place by the oral route through ingestion of food,milk or water contaminated by contact with faecal mattar of the typhoid patient.The bacteria spread through faecal mattar by house flies. Symptoms-1.Headache and typhoid fever which rises maximum in the afternoon. The temperature increases each day in the first week. 2.High fever in the second week.Fever gradually declines during 3rd and 4th day. 3.In nutshell symptoms of typhoid include continuous fever often with delirium, slow pulse, tender and distended abdomen,diarrhoea with water-green stools. Prevention-1.Proper sanitation and disposal of faecal mattar prevents infection 2.TAB-vaccination provides immunity for 3 days. 3.Typhoral oral vaccine also prevents typhoid. Control-There are standard drugs e.g., Chloromycetin which cure typhoid.
  • 16. THANKS.