HOST DEFENSES(IMMUNITY) By DR Mohammad Ayaz MBBS, MPH, MSc Associate Professor & Head Of Dept, Community Medicine
LEARNING OBJECTIVES Describe the EPI Program. Enlist various vaccines used in EPI. Explain Cold Chain and its importance.
Today’s Situation • 10.5 million infant and childhood deaths each year in the developing world • 70% are due to five conditions: pneumonia, diarrhea, measles, malaria, and malnutrition. • At least 3/4 of all childhood illness episodes are caused by one of these conditions
4 million neonatal deaths annually. • Two thirds of neonatal mortality occur in the first week of life, of these two thirds die within the first 24 hours of life
Immunization • Quality and Safety Providing an ineffective vaccine is worse than providing no vaccine at all.
Immunization • Vaccine potency • Proper vaccine handling • Proper conditions and • Use of Vaccine Vial Monitors • Safe injection practices • Clean work space • Hand washing • Sterile needle and syringe for each injection • Assuring sterile vaccines and diluents. • Appropriate sharps and waste collection and disposal
Vaccine-PREVENTABLE Diseases AnthraxCervical CancerDiphtheriaHepatitis AHepatitis BHaemophilus influenzae type b (Hib) Human Papillomavirus (HPV)Influenza (Flu)Japanese Encephalitis (JE)Lyme Disease MeaslesMeningococcalMonkeypoxMumpsPertussis (Whooping Cough)PneumococcalPoliomyelitis (Polio)RabiesRotavirus Rubella (German Measles)Shingles (Herpes Zoster)SmallpoxTetanus (Lockjaw)TuberculosisTyphoid FeverVaricella (Chickenpox)Yellow Fever
Definition • Immunization (vaccination) is a way to trigger your immune system and prevent serious, life-threatening diseases. • Vaccination is the administration of antigenic material (the Vaccine) to produce immunity to a disease. Vaccines can prevent or ameliorate the effects of infection by a pathogen. Definition
Vaccination • Vaccination (Latin: vacca—cow) is so named because the first vaccine was derived from a virus affecting cows, which provides a degree of immunity to smallpox.
Expanded Programme Of Immunization (EPI) • The Global program of immunization was launched following a resolution of world health Assembly in 1974
Expanded Programme for Immunization The EPI in Pakistan was initiated as a pilot project in 1976. Was launched at federal level in 1978. Was Established nation-wide by 1981. The programme currently targets seven vaccine preventable diseases i.e. Tuberculosis, Diphtheria, Pertusis, Tetanus, Poliomyelitis Heapitis B Measles
Without effective immunization, • it is estimated that 100,00 deaths due to measles, 70,000 cases of neonatal tetanus and 20,000 paralytic cases of poliomyelitis would occur in Pakistan each year.
The routine immunization schedule • targets one dose of BCG, • 3 doses OPV and DPT vaccines • and one dose of measles vaccine in the first year of life. • At birth dose of OPV is scheduled if there is health staff contact with the infant before it reaches 6 weeks age.
Immunization Immunization Schedule for Infants: Recommended by WHO - Expanded Program on Immunization
Immunization Schedule for Infants: Recommended by WHO - Expanded Program on Immunization . EPI Vaccination Schedule
. EPI Vaccination Schedule Vaccination Schedule For Married Women 15-45 Years
CONTRA-INDICATIONS General Contraindications • Any acute illness • Severe malnutrition. • In known cases of immune deficiency. RELATED TO GROUPS OF VACCINES • During pregnancy there is mild to fatal damage to the foetus. • The continuous administration of glucocorticoid usually prednisolone impairs the body response to a primary antigenic stimulation but the secondary response is not appreciably affected. • Total body exposure to ionizing radiation. • Administration of anti-metabolites such as 6-M.P. or azothioprine, nitrogen mustard, actinomycin, as they inhibit the primary response.
INDIVIDUAL VACCINES • BCG is contraindicated in extensive dermatosis. • Whooping cough- the appearance of any neurological symptoms after the first or second dose is an absolute contraindication. • Toxoids- No contraindication for TT. • For Polio Vaccine Diarrhea, No polio vaccine to be administered within three weeks of tonsillectomy. • Measles- History of febrile convulsions and active tuberculosis.
Smallpoxwas the first disease people tried to prevent by inoculating themselves. • Smallpoxinoculation was started in India and China before 200 BC. • In 1718, Lady Mary Wortley Montague reported that the Turks have a habit of deliberately inoculating themselves with fluid taken from mild cases of smallpox and she inoculated her own children. • In 1796Edward Jenner inoculated using cowpox (a mild relative of the deadly smallpox virus). • The term vaccination was first used by Edward Jenner in 1796. • Louis Pasteur further adapted in his pioneering work in microbiology. HISTORY
Vaccination (Latin: vacca—cow) is so named because the first vaccine was derived from a virus affecting cows—the relatively benign cowpox virus—which provides a degree of immunity to smallpox. • 'vaccination' and 'immunization' generally have the same meaning. • This distinguishes it from inoculation which uses unweakened live pathogens, although in common usage either is used to refer to an immunization. • The word "vaccination" was originally used specifically to describe the injection of smallpox vaccine. HISTORY
USES OF IMMUNOLOGY For the immunization programs. In hypersensitivity and drug reaction. Forecasting of epidemics. Serological diagnosis and blood grouping. Carrier detection. Organ transplantation. USES OF IMMUNOLOGY
Four different types of vaccines are currently available. • Attenuated (weakened) live virus is used in the measles, mumps, and rubella (MMR) vaccine and the varicella (chicken pox) vaccine. These vaccines may cause serious infections in people with weakened immune systems. • Killed (inactivated) viruses or bacteria are used in some vaccines, such as the influenza vaccine. These vaccines are safe, even in people with weakened immune systems. • Toxoid vaccines, such as the diphtheria or tetanus vaccines, contain a toxin or chemical made by the bacteria or virus. They make you immune to the harmful effects of the infection rather than the infection itself. • Biosynthetic vaccines contain human-made substances that the immune system thinks are infectious organisms. The Hib (Haemophilus influenzae type B) conjugate vaccine is one example.
BARRIERS AND INNATE IMMUNITY • Immune system includes barriers These barriers are • innate immunity (with you from birth) skin, stomach acid, mucus (which traps bacteria and small particles), the cough reflex, and enzymes in tears and skin oils. If an antigen gets passed the external barriers, it is attacked and destroyed by other parts of the immune system.
BARRIERS AND INNATE IMMUNITY continued • BLOOD COMPONENTS The immune system includes certain types of white blood cells. It also includes chemicals and proteins in the blood, such as complement proteins and interferon. Some of these directly attack foreign substances in the body, and others work together to help the immune system cells. • INFLAMMATION The inflammatory response (inflammation) occurs when tissues are injured by bacteria, trauma, toxins, heat, or any other cause. Chemicals including histamine, bradykinin, serotonin, and others are released by damaged tissue. These chemicals cause blood vessels to leak fluid into the tissues, causing swelling. This helps isolate the foreign substance from further contact with body tissues.
ANTIGEN: “An antigen is a substance which when introduced into the body stimulates specific immune response”. Chemically an antigen may be a protein,carbohydrate,lipid or nucleic acid and usually foreign or nonself to the body. ANTIBODY: “An antibody is a protein substance produced in response to a specific antigen with which it combines chemically”. This reaction of antibody results in neutralization and elimination of antigen.
IMMUNITY “Reaction of the body towards any foreign substance or non self”. The immune response is how your body recognizes and defends itself against bacteria, viruses, and substances that appear foreign and harmful to the body Immune mechanism reacts with every foreign substance whether visible or microscopic. Host defense(Immunity) may be Natural Immunity Acquired Immunity
Conti A-Natural Immunity:It is the resistance offered by the body under the normal conditions without any external stimulation. This is possessed by birth. It may be species immunity eg Rats mice and dog against tuberculosis. Racial immunity, Negro's to yellow fever. B-Acquired Immunity:The immunity which is acquired by natural or artificial means and may be active or passive. ACTIVE IMMUNITY It is the immunity which when one individual develops as a result of infection or by specific immunization.
Acquired Immunity • Naturally Acquired Immunity • Immunity from infection: “Naturally acquired active immunity”. Often lifetime or long-lasting. • • Immunity from mother to fetus via transplacental transfer or colostrom results in “Naturally acquired passive immunity”. Short-lived, e.g. 6 months. • – Artificially Acquired Immunity • • First performed for smallpox by Edward Jenner • Immunity from vaccine: Artificially acquired active immunity • Artificially acquired passive immunity acquired by injection of humoral antibodies: short term immunity. Serum ”Antiserum”
IMMUNITY Conti Active immunity depends upon the Humoral and cellular responses of the host. HUMORAL RESPONSE:Comes from the B lymphocytes and manufactures specific antibodies. The antibodies are localized in the immunoglobulin of serum. Immunoglobulins are divided into 5 main classes IgG, IgM,IgA,IgD and IgE. CELLULAR RESPONSE: Is achieved by the T lymphocytes. Infectious disease like M.TB, M.Leprae, S.typhi, Candida albicans and many viruses escape from the Humoral response.Cellular immunity provides protection against such diseases.
IMMUNITY Conti Active Immunity may be acquired in three ways Following clinical infections (chickenpox, rubella and measles). Sub-clinical or in-apparent infection(Polio and diphtheria). Following Immunization (Live or killed vaccine).
IMMUNITY Continued 2. PASSIVE IMMUNITY:When antibodies produced in one body are transferred to another to induce protection against disease. Passive immunity may be induced I. By administration of an antibody containing preparation(antisera,immune globulin) II. By transfer of maternal antibodies across the placenta. III. By transfer of lymphocytes.
PASSIVE IMMUNITY Continued: Passive immunity differs from active immunity as Immunity develops rapidly. Immunity produced is temporary. There is no education of the reticulo-endothelial system. Passive immunization is useful for individuals who cannot form antibodies or take time to develop antibodies following active immunization.
HERD IMMUNITY “It is the level of resistance of a community or group of people to a particular disease”. Herd immunity implies group protection beyond that afforded by the protection of immunized individuals. An epidemic declines before the whole population becomes immune. If two third population in a community becomes immune, the remaining one third become immune. The elements which contribute to herd immunity are Occurrence of clinical and sub clinical infection in the herd Immunization of the herd. Herd structure ( Birth, death and population mobility).
IMMUNE RESPONSE A. PRIMARY IMMUNE RESPONSE: When an antigen is administered for the first time. After 3-10 days antibodies appear in the blood. The first antibody is IgM which rises steadily for 2-3 days reaches to peak and then declines as fast as it developed. If the antigenic stimulus was sufficient IgG antibody appears in a few days IgG reaches to peak in7-10 days and falls over a period of weeks or months.
IMMUNE RESPONSE continued Secondary (BOOSTER) RESPONSE: Secondary response is different from the primary response in a number of ways Shorter latent period. Production of antibody more rapid. Antibody more abundant. Antibody response maintained at higher levels for a longer period. The antibody have greater capacity to bind the antigen.
Humoral (Antibody-Mediated) Immunity • – Humoral system responds to extra-cellular foreign invaders. • – The humoral immune system involves antibodies produced by “plasma cells” via B cells (B-lymphocytes) in response to a specific antigen. • B Cells interact with invader via their receptor sites and differentiate into plasma cells which produce antibodies. • Some B cells become “memory cells” which produce the “secondary response”. • – Antibodies primarily defend against bacteria, viruses, and toxins in blood plasma and lymph.
Cell-Mediated Immunity (Continued) • •– The cell-mediated immune system makes use of T cells (T-lymphocytes) and does not involve antibody production. Response involves “T” cells • T- Cytotoxic cells • T- Helper cells • T cells do not interact with invader but destroys cells infected by invader by recognizing “foreign” abnormal proteins - not “self”. • Cellular immunity responds primarily to intracellular viruses, multicellular parasites, tissue transplants, and cancer cells.
Protective Outcomes of Antigen-Antibody Binding • Neutralization of foreign substance or invader • Immobilization and prevention of adherence to host cells. • Agglutination and precipitation assisting phagocytosis. • Opsonization - facilitates phagocytosis. • Activation of complement. • Antibody-Dependent Cellular Cytotoxicity (ADCC).
IMMUNIZING AGENTS The immunizing agents may be classified as Vaccines. Immunoglobulins. Antisera. VACCINES Vaccine is an immuno-biological substance designed to produce specific protection against a given disease. It stimulates the production of protective antibody and other immune mechanisms.
VACCINES Conti Vaccine may be prepared from Live modified organisms Inactivated or killed organisms Extracted cellular fractions Toxoids or combinations of these. More recent preparations are sub-unit vaccines and recombinant vaccines.
LIVE VACCINES • ( BCG, Measles, Oral polio) are prepared from live attenuated organisms. • These organisms are passed repeatedly in the laboratory in tissue cultures or chick embryos and have lost their capacity to induce full blown disease but retain the Immunogenicity.
LIVE VACCINES Conti Live vaccines are more potent immunizing agents than killed vaccines because Live organisms multiply in the host and the resulting antigenic dose is larger than what is injected. Have all the major and minor antigenic components. Engage certain tissues of body( intestinal mucosa by polio). Other mechanisms such as persistence of latent virus.
LIVE VACCINES Conti LIVE VACCINES should not be administered to persons who have: Immune deficiency disease, leukemia, lymphoma, malignancy or therapy with corticosteroids, alkylating agents, anti-metabolic agents or radiation and pregnancy. When two live vaccines are required they should be given either simultaneously at different sites or with an interval of at least three weeks.