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- 2. Immunology • the studyof the human immune system. • word "immunity" derives from the Latin immunis, meaning exemption from military service, tax payments or other public services. • Here it means free from burden. In this case burden refers to disease caused by microorganisms or their toxic products. • Study of cells, organs and chemical components of the immune system which fight against the infectious agents.
- 3. Immunity • Ability ofbody to specifically counteract with foreign organisms. • State of resistance or insusceptibility exhibited by the host to toxic chemicals,mos and foreign cells.
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- 5. Thucydides ➢ The earliestknown mention of immunity was during the plague of Athens in 430 BC by Thucydides. ➢ He was dubbed the father of "scientific history" due to his strict standards of evidence-gathering and analysis in terms of cause and effect without reference to intervention by the gods. ➢ He noted that people who had recovered from a previous bout of the disease could nurse the sick without contracting the illness a second time.
- 6. Chinese-smallpox ➢ The Chinesepracticed the oldest documented use of variolation, dating back to the fifteenth century. ➢ They implemented a method of "nasal insufflation" administered by blowing powdered smallpox material, usually scabs or pus , up the nostrils.
- 8. Edward Jenner scientist whopioneered the concept of vaccines including creating the smallpox vaccine, the world's first vaccine. Born 17 May 1749 Berkeley, Gloucestershire, England Died 26 January 1823 (aged 73) Berkeley, Gloucestershire, England Nationality British Known for Smallpox vaccine Vaccination Scientific career Fields Medicine/surgery, natural history Academic advisors John Hunter
- 9. In 1796, hecarried out his now famous experiment on eight-year-old James Phipps. Jenner inserted pus taken from a cowpox pustule and inserted it into an incision on the boy's arm. He was testing his theory that milkmaids who suffered the mild disease of cowpox never contracted smallpox, one of the greatest killers of the period, particularly among children. Jenner subsequently proved that having been inoculated with cowpox Phipps was immune to smallpox. He submitted a paper to the Royal Society in 1797 describing his experiment, but was told that his ideas were too revolutionary and that he needed more proof. Undaunted, Jenner experimented on several other children, including his own 11-month-old son. In 1798, the results were finally published and Jenner coined the word vaccine from the Latin 'vacca' for cow. Dr Jenner performing his first vaccination on James Phipps, a boy of age 8. 14 May 1796
- 10. Louis Pasteur- Chickencholera • In the summer of 1880, Pasteur found a vaccine by chance, after forgetting one of his cultures. • With the help of a colleague Charles Chamberland, he showed that Chicken cholera germs from an old culture that had been around for some time lost their ability to transmit the disease. • The inoculated chickens did not die. • Pasteur repeated what he had done but with a fresh culture of chicken cholera germs. • Pasteur reasoned that a new culture would provide more potent germs.
- 11. • Two groupsof chickens were inoculated; one that had been given the old culture and one group that had not. • Those chickens that had been given the old culture survived, those that had not died. • The chickens that had been inoculated with the old culture had become immune to chicken cholera. • Pasteur believed that their bodies had used the weaker strain of germ to form a defence against the more powerful germs in the fresher culture. • Pasteur had found a way of producing the resistance without the risk of the disease.
- 12. Innate or naturalimmunity Acquired immunity
- 13. Innate or Naturalimmunity • Immunity with which an individual is born is called innate or natural immunity. • Innate immunity is provided by various components such as Skin, Mucus membrane, Phagocytic cells etc. • Innate immunity acts as first line of defense to particular microorganisms.
- 14. Mechanism of innateimmunity • Anatomical barrier • Physicochemical barrier • Phagocytic barrier or Phagocytosis • Inflammatory barrier or Inflammation
- 16. Types of innateimmunity • Species immunity • Racial immunity • Individual immunity
- 17. 1. Species immunity •If one species is resistant to certain infection and the other species is susceptible to the same infection then it is called as species immunity. • Anatomic, physiological and metabolic differences between species determine species immunity. • Eg- Birds are resistant to anthrax but Human are susceptible. It is simply because higher body temperature of birds kills Bacillus anthracis. • Anatomic differences between species also determine species immunity. Eg- Human are more susceptible to skin infection whereas Cattles are more resistant to the same skin infection. It is because of tough and hairy skin (hides) of Cattles. • Entire human species is resistance to the plant pathogens.
- 18. 2. Racial immunity •If one race is susceptible while other race is resistant to same infection, then it is called Racial immunity. • Eg-certain African race are more resistant to malaria and yellow fever where are Asian or Americans are susceptible to same infection. • Similarly Orientals (East Asia) are relatively resistant to syphilis. • Algerian sheep, for example, are immune to anthrax, a disease commonly fatal to other breeds of sheep • Racial immunity is determined by difference in Socio- economic status, habitat, culture feeding habits, environments, genetic, etc.
- 20. 3. Individual immunity •If one individual of certain race or cast is resistant while other individuals of same race or cast are susceptible to certain infection, then it is called as individual immunity • Individual immunity is determined by various factors such as health status, nutritional status, previous illness, personal hygiene, genetic differences etc. • For examples; Individual with genetic deficiency of glucose-6 phosphate dehydrogenase are resistant to Malaria.
- 23. Acquired or Developedimmunity: • Immunity which is developed later in life after microbial infection in host is called as Acquired or developed immunity. • If an individual is infected with chicken pox virus, he/she become resistant to same virus in later life. • Acquired immunity is provided by – Antibodies and certain T-lymphocytes. • Components of acquired immunity such as Antibodies and T- cells are specific to particular microorganism. Therefore acquired immunity is also known as Specific immunity. Characteristics of Acquired immunity • Specificity • Self/non-self recognition • Immunological memory • Diversity
- 24. • Types ofacquired immunity: • Active immunity • Passive immunity
- 25. 1. Active immunity: •The immunity induced by exposure to a foreign antigen is called active immunity. • the resistance developed by an individual after contact with foreign antigens, e.g., microorganisms. This contact may be in the form of: • clinical or subclinical infection, • immunization with live or killed infectious agents or their antigens, or • exposure to microbial products, such as toxins and toxoids. • If host itself produces antibodies, it is called active immunity. • It is of two types • Naturally acquired active immunity: • immunity provided by natural infection. • Artificially acquired active immunity: • Immunity provided by vaccination. Vaccination
- 26. 2. Passive immunity: •When immunity is conferred by transfer of serum or lymphocytes from a specifically immunized individual, it is known as passive immunity. • If host does not produce antibodies itself but antibodies produced in other host provides immunity, than it is known as Passive immunity. It is of two types – Naturally acquired passive immunity: IgG antibody produced in mother cross placenta and protects fetus. – Artificially acquired passive immunity: if preformed antibody are injected into host for immunity. Eg. Anti-venom, Rabies vaccine (*it is not a vaccine, it is preformed anti-rabies antibody)
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- 28. Difference between Activeand Passive Immunity
- 30. What is herdimmunity? • When most of a population is immune to an infectious disease, this provides indirect protection—or population immunity (also called herd immunity or herd protection)—to those who are not immune to the disease. • For example, if 80% of a population is immune to a virus, four out of every five people who encounter someone with the disease won’t get sick (and won’t spread the disease any further).
- 31. • Vaccination programscreate herd immunity by greatly reducing the number of susceptible individuals in a population. • Even if some individuals in the population are not vaccinated, as long as a certain percentage is immune (either naturally or artificially), the few susceptible individuals are unlikely to be exposed to the pathogen. • However, because new individuals are constantly entering populations (for example, through birth or relocation), vaccination programs are necessary to maintain herd immunity.