Immunity and Infection Chapter 17 © 2012 McGraw-Hill Companies. All Rights Reserved.

2 The Chain of Infection Links in the chain  Transmitted through a chain (six links) Pathogen - disease causing microorganism Reservoir - natural environment of the pathogen: person, animal, or environmental space such as soil or water Portal of exit – saliva, mucous membranes, blood, feces, nose Means of transmission  Direct transmission – sneezing, coughing  Indirect transmission – rats, ticks, mosquitoes  Vectors – carrier of the pathogen from one host to another Portal of entry  Direct contact with or penetration of the skin  Inhalation through mouth or nose  Ingestion New host  Breaking the chain at any point can prevent disease

© 2012 McGraw-Hill Companies. All Rights Reserved. 3 Figure 17.1 The Chain of Infection

© 2012 McGraw-Hill Companies. All Rights Reserved. 4 The Body’s Defense System Physical and chemical barriers  Skin, mucous membranes, respiratory tract The Immune System  Immunological Defenders Neutrophils Macrophages – “big eaters” Natural killer cells Dendritic cells – eat pathogens and activate lymphocytes Lymphocytes  T-cells  Helper, killer, and suppressor  B-cells  Memory cells  Antigens and antibodies  “Self” versus “non-self”

© 2012 McGraw-Hill Companies. All Rights Reserved. 5 Figure 17.2 The Lymphatic System

© 2012 McGraw-Hill Companies. All Rights Reserved. 6 Inflammatory and Immune Responses Histamine Dilation of blood vessels, heat, redness, swelling The immune responses: natural and acquired  Phase 1 – Dendritic cells are drawn to the site  Phase 2 – helper T cells multiply Production of killer T and B cells Cytokines – chemical messengers  Phase 3 – killer T cells strike Cell-mediated immune response Antibody-mediated immune response  Phase 4 – last phase Slow down activity Debris excreted from body

© 2012 McGraw-Hill Companies. All Rights Reserved. 7 Figure 17.3 The Immune Response

© 2012 McGraw-Hill Companies. All Rights Reserved. 8 Immunity An infected person may never get the same illness again  Lymphocytes reserved by memory T and B cells = acquired immunity Symptoms and contagion  Incubation – when viruses are multiplying in the body or when bacteria are actively multiplying Will not feel symptoms until the second or third phase of the immune response cycle  Prodromal period – symptoms first appear, but the infected host may have acquired immunity

© 2012 McGraw-Hill Companies. All Rights Reserved. 9 Epidemics and Pandemics Epidemic: a rapidly spreading (greater than expected) disease or health-related concern Pandemic: widespread epidemics Results only if three criteria are met: 1. Little or no pre-existing immunity to the new virus 2. Efficient human-to-human transmission of the virus 3. New virus can cause illness May occur in specific populations or regions

© 2012 McGraw-Hill Companies. All Rights Reserved. 10 Immunization The process of priming the body to remember an encounter with a specific antigen Types of vaccines  VACCINE- Introduction of a killed or weakened pathogen to stimulate the body to produce antibodies  ACTIVE IMMUNITY - person produces his or her own antibodies to the microorganism  PASSIVE IMMUNITY- injection of antibodies produced by other human beings or animals  ACQUIRED IMMUNITY- the ability of a memory lymphocytes to remember a previous infection (chicken pox)

Table 17.2 Immunizations Recommended for Teens and College Students

© 2012 McGraw-Hill Companies. All Rights Reserved. 12 Immunization Issues Vaccine shortages in the U.S. Vaccine safety Are they really worthwhile?

© 2012 McGraw-Hill Companies. All Rights Reserved. 13 Allergy: The Body’s Defense System Gone Haywire  Allergies: body defends against harmless substances  Allergens: substances that provoke allergies Pollen, animal dander, dust mites and cockroaches, molds, food, insects  Allergic response: due to antibody Immunoglobulin E (IgE) Anaphylaxis

© 2012 McGraw-Hill Companies. All Rights Reserved. 14 Figure 17.4 The Allergic Response

© 2012 McGraw-Hill Companies. All Rights Reserved. 15 Dealing with Allergies Avoidance Medication Immunotherapy or “allergy shots”

© 2012 McGraw-Hill Companies. All Rights Reserved. 16 Figure 17.5 Pathogens

© 2012 McGraw-Hill Companies. All Rights Reserved. 17 Pathogens and Disease Pathogens: bacteria, viruses, fungi, protozoa, parasitic worms, prions Bacterium – microscopic single-celled organism  Pneumonia  Meningitis  Strep throat and other streptococcal infections  Toxic shock syndrome and other staphylococcal infections  Tuberculosis  Tickborne infections  Ulcers  Other bacterial infections Tetanus, Clostridium difficile, pertussis, urinary tract infections

© 2012 McGraw-Hill Companies. All Rights Reserved. 18 Antibiotic Treatment Actions of antibiotics Antibiotic resistance Proper antibiotics usage  Don’t take an antibiotic every time you are sick; effective for bacteria, ineffective for virus  Use antibiotics as directed; finish full course  Never take an antibiotic without an prescription

© 2012 McGraw-Hill Companies. All Rights Reserved. 19 Viruses Viruses are parasites – they take what they need Most common contagious disease  Common cold  Influenza  Measles, mumps, rubella  Chicken pox, cold sores, and other herpesvirus infections Varicella-zoster virus Herpes simplex virus (HSV) types 1 and 2 Epstein-Barr virus (EBV) (causes mononucleosis)  Viral encephalitis  Viral hepatitis (A, B, C)  Poliomyelitis  Rabies  Human papillomavirus (HPV) Treating viral illnesses

© 2012 McGraw-Hill Companies. All Rights Reserved. 20 Figure 17.6 Life Cycle of a Virus

© 2012 McGraw-Hill Companies. All Rights Reserved. 21 Types of Pathogens Fungi  Primitive plant – yeast infections, athlete’s foot, jock itch, ringworm  Candida albicans Protozoa  Microscopic single-celled animal: malaria, giardiasis, trichomoniasis, trypanosomiasis, amoebic dysentery Parasitic worms  Largest organism that can enter the body to cause infection: tapeworm, hookworm, pinworm (most common) Prions  Fatal degenerative disorders of the CNS linked to “proteinaceous infectious particles” or prions  Lack DNA and RNA  Transmissible spongiform encephalopathies (TSEs) Spongelike holes in the brain Creutzfeldt-Jakob disease in humans Bovine spongiform encephalopathy (BSE) or “mad cow disease” in cattle

© 2012 McGraw-Hill Companies. All Rights Reserved. 22 Emerging Infectious Diseases Selected infections of concern:  West Nile virus  Severe acute respiratory syndrome (SARS)  Rotavirus  Escherichia coli 0157:H7  Hantavirus  Ebola

© 2012 McGraw-Hill Companies. All Rights Reserved. 23 Factors Contributing to Emerging Infections Drug resistance Poverty Breakdown of public health measures Travel and commerce Mass food production and distribution Human behaviors Bioterrorism

© 2012 McGraw-Hill Companies. All Rights Reserved. 24 Other Immune Disorders: Cancer and Autoimmune Diseases If the immune system breaks down Getting older Certain immune disorders (HIV) Chemotherapy Autoimmune diseases  Rheumatoid arthritis  Systemic lupus erythematosus

© 2012 McGraw-Hill Companies. All Rights Reserved. Support Your Immune System How to support your immune system General guidelines Balanced diet Enough sleep Exercise Don’t smoke Moderation of alcohol Wash your hands Avoid contact with contagious people Plenty of clean water Avoid contact with vermin Practice safe sex Do not use injectable drugs Vaccinations 25

© 2012 McGraw-Hill Companies. All Rights Reserved. IMMUNITY AND INFECTION Chapter 17 26