Types of immunity and vaccination Starting activity: What is immunity How do we become immune?

Learning Objectives Learners should be able to demonstrate and apply their knowledge and understanding of: the differences between active and passive immunity, and between natural and artificial immunity autoimmune diseases the principles of vaccination and the role of vaccination programmes in the prevention of epidemics possible sources of medicines the benefits and risks of using antibiotics to manage bacterial infection.

Types of immunity Immunity = the means by which the body protects itself from infection Immunisation = The process of artificially inducing immunity. Immunity Natural Artificial Active Organisms own immune system is stimulated by contact with a disease Passive Antibodies are passed to an individual eg in Colostrum/breast milk or via the placenta Organisms own immune system is stimulated by a vaccine Antibodies obtained chemically and administered often by a jab

Autoimmune diseases The immune system stops recognising some cells as ‘self’ to will attack them causing inflammation and destruction of healthy tissues Three of the most common Type 1 diabetes damages the β cells in the pancreas Rheumatoid arthritis attacks joints causing scarring and swelling Lupus which can damage many organs such as kidneys and liver and skin often causing a persistent facial rash There are no cures for these diseases but can be managed with other medications such as insulin injections or immunosuppresants

Artificial Active Immunity Vaccines To make the pathogen safe for a vaccine there are a few options Dead or Inactive pathogens Whooping cough Attenuated/weakened pathogens which are live Rubella, Polio Antigens from the pathogen Influenza These can be genetically engineered e.g. hepatitis Modified toxins from the pathogen Diptheria

Vaccination programmes Approximate age Vaccination 2 months DTP, Tetanus and Pertussis (whooping cough), Polio, Meningitis type C 4 months DTP, Polio (both 2nd doses) 6 months DTP, Polio (3rd doses) 15-18 months MMR combined vaccine 4-5 years DTP combined vaccine (4th dose), MMR combined vaccine (2nd dose), Polio booster 11-13 years Rubella (German measles) 13 years Tuberculosis (BCG) 15 years Tetanus and Diptheria – booster Polio booster.

How Vaccines Work Small, safe doses are administered either by injection or orally. This promotes the primary response by clonal selection Second injections may be given to strengthen the response The B and T lymphocytes make memory cells, which will divide rapidly by mitosis (clonal expansion) if you come into contact with the infection Vaccines vary in how long they last Cholera 2years Tetanus 10 years Polio or MMR may last for life

Herd Immunity This is the protection gained by a community when vaccination rates are very high usually over 85% They reduce epidemics (local or national infection spreading rapidly) Pandemics –infection across the world will trigger international vaccination programmes such as the SARS (severe acute respiratory syndrome) and bird flu epidemics.

Spanish Flu 1918-1920 The Spanish flu pandemic caused over 50 million deaths which was over 3% of the world population and more than world war1. Flu normally kills very young and elderly people but Spanish flu was most deadly to younger/healthy people. Researchers think that the virus provoked a huge cytokine response called a cytokine storm which causes a massive accumulation of tissue fluid and WBC at sites of infection such as lungs.

Control of disease by vaccination Important features of a successful vaccination programme Development of a suitable vaccine Few if any side effects The mechanisms to produce, store and transport the vaccine Administering vaccine at the right time and right group appropriately Vaccinate the vast majority (high risk groups) HERD IMMUNITY

Small pox the last jenneration! Reason for the successful eradication of smallpox Explanation Simple safe vaccine Live vaccine especially effective and persists in the body longer Easy to produce and administer Virus was genetically stable Lethal nature of disease Symptoms easily recognised – stops spread Virus doesn’t remain in body after infection No host/vector organism involved A coordinated worldwide vaccination programme

Measles lower success rate in control by vaccination Vaccine is only 95% effective Measles antigens are complex Some children do not respond effectively to the measles vaccine – need boosters Parental concern over MMR vaccine

Cholera and TB Cholera Remains in intestines beyond reach of antibodies Oral vaccine being developed Mobile populations Antigenic drift and antigenic shift is rapid Tuberculosis Increase in HIV – more opportunistic infections of TB Increasing poverty – overcrowding due to war / unrest Mobile populations Increasingly older populations

Medications Drugs can treat disease in a number of ways Pain killers e.g. aspirin, morphine Antibiotics to destroy pathogens e.g. penicillin Hormones e.g. insulin Restore functions and adjust processes in the body e.g. statins reduce blood cholesterol, digoxin from foxgloves can modify the heart beat in atrial fibrillation

Sources of Drugs Many are naturally occurring Aspirin comes from willow bark Morphine from opium poppies Penicillin from mould Vancomycin is a new powerful antibiotic from a soil fungus We need to maintain biodiversity as these organisms may be potential sources of new drugs

Pharmacogenetics Pharmaceutical companies can also design and modify drugs using huge data bases of information about the action of various chemicals They can also be personalised to your genetic make up. Some people respond negatively to a drug that can help others. Understanding how different genes interact with a drug can be very important to prevent damaging side effects Pharmacogenetics

Plenary What about the control of malaria? – use your books to find out why it is hard to control through vaccination. Try exam questions Complete card loop in class.