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Infection and Immunity

Learn about the nature of infections, types of pathogens, body defenses, immunity, and common infectious diseases. Explore causes, transmission, symptoms, diagnosis, and treatment of sexually transmitted infections.

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Infection and Immunity

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  1. Infection and Immunity

  2. Chapter 12Infection and Immunity Learning Outcomes: • Discuss the nature of infection, types of pathogens, and the course of infections • Describe the body’s defenses against infection • Discuss immunity and immunization • Describe common infectious diseases • Discuss the causes, transmission, symptoms, diagnosis, and treatment of sexually transmitted infections

  3. Infection • Infectious(communicable) diseases caused by pathogens which are disease-causing organisms • Types of pathogens include: viruses protozoa bacteria parasitic worms fungi • Modes of transmission

  4. Microbes & Pathogens • Most microorganisms are not pathogenic, some essential to our health and life • Microbes are either endogenous (originate inside the body or exogenous (originate outside the body) • Immune system normally recognizes and destroys invasive pathogens and rids the body of diseased or worn-out cells; however when system is compromised or overrun, infection can occur

  5. Bacteria • Single cell organisms, live in soil, air, plants, and animals including humans • Harmful bacteria release toxins • Use nutrients from host to reproduce • Grouped in families: Staphylococci, Streptococci, Chlamydia, Rickettsiae • Typically treated with antibiotics; however some are becoming resistant (MRSA) • Vaccinations are available for some (DPT)

  6. Viruses • Contain DNA or RNA, “hijack” the cell • Some remain dormant for long periods; others reproduce quickly. • Enter the body through eyes, nose, skin, mouth, or genital tract • Antibiotic treatment is ineffective • Prevention including immunizations is most effective in combating

  7. Other Pathogens Fungi – plant organism (yeasts and mold) • Infections typically occur on skin • Ringworm (fungal infection of hair, skin, nails) • Candida (yeast-like fungus) • diaper rash, thrush (use of antibiotics) Protozoa– single-celled aquatic animals • Malaria and diarrhea – major health problems in tropical climates and developing countries Parasitic Worms (helminths)–multi-cellular • Pinworms, tapeworms, flukes – Flourish in intestines; • can be round or flat, microscopic to several feet in length

  8. Body’s Defenses First Line of Defense: Physical and Chemical Barriers Skin Mucous Membranes Cilia Chemical Defenders Second Line of Defense: Immune System Specialized white blood cells lymphocytes, phagocytes, NK cells Immune response: Cell-mediated immunity Antibody-mediated immunity Nonspecific immune response

  9. Specific Immune Response • If nonspecific response cannot destroy antigens, lymphocytes are recruited. • T-Cells [Helper T cells, Killer T cells, Suppressor T-Cells] • B-Cells [produces antibodies, memory cells] • Lymph nodes

  10. Immunity & Immunization Innate Immunity: mother’s antibodies in fetus/newborn, temporary and limited Acquired Immunity: Develops after birth Active: Natural Acquired Active Immunity (NAAI) Develop naturally after producing antibodies when infected with the pathogen Artificially Acquired Active Immunity (AAAI) Immunizations with weakened or killed pathogen – body produces antibodies Passive: injected with antibodies

  11. Immune System Disorders • Allergies: Hypersensitivity to normally harmless substances; triggers release of histamine – causing typical symptoms; anaphylaxis – severe reaction • Asthma: triggers include allergens, pollutants, stress • Autoimmune Disorders: immune system attacks healthy cells as if they were antigens Rheumatoid arthritis, lupus, multiple sclerosis

  12. Common Infectious Diseases • “Common Cold” – over 200 viruses • Influenza – viral • 3 families type A, B, C – mutate – need annual flu shot • Pneumonia – viral or bacterial • Legionnaire’s Disease – deadly bacterial pneumonia • Tuberculosis – bacteria high incidence among IV drug user, homeless, people with HIV/AIDS • Lyme Disease – bacteria spread by deer ticks • Mononucleosis – Epstein-Barr virus • More prevalent between 16-30 years of age

  13. Sexually Transmitted Infections • Transmitted through sexual contact including: vaginal or anal intercourse, oral sex, transmission from mother to child during child-birth and breastfeeding as well as contact with contaminated items • Bacterial STIs – can be treated, may be asymptomatic Gonorrhea Syphilis Chlamydia – 2nd most common, can cause PID in women

  14. Sexually Transmitted Infections Viral STIs – no cure, treatments may provide relief HIV/AIDS – long period from HIV infection to AIDS • Transmitted through contaminated blood, semen, vaginal secretions or breast milk Genital Herpes • Transmitted by genital and oral contact • Infected women higher risk of miscarriage, vaginal birth dangerous for baby – C-section results Viral Hepatitis – Hepatitis B, C, D – sexual transmission • Vaccine available for hepatitis B & D, B is mandated HPV/Genital Warts • World’s most common, most will contract in lifetime • Can progress to genital warts – linked to cervical cancer • HPV vaccines available for both men and women

  15. Sexually Transmitted Infections

  16. Sexually Transmitted Infections

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