Infection and Immunity

Chapter 12 Infection 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

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

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

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)

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

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

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

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

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

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

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

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

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

Sexually Transmitted Infections

Sexually Transmitted Infections