Immunity and Infection Chapter 14 PDF

Because learning changes everything. ® Immunity and Infection Chapter 14 © McGraw Hill LLC. All rights reserved. No re...

Because learning changes everything. ® Immunity and Infection Chapter 14 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC.  The Body’s Defense System Immune system is the body’s collective set of defenses that includes surface barriers as well as the specialized cells, tissues, and organs that carry out the immune response. Protects us not just from pathogens (disease-causing organisms) but also from cancer Physical and chemical barriers: Skin Mucous membranes Respiratory tract, lined with both mucous membranes and cilia © McGraw Hill LLC 2  The Immune System: Cells, Tissues, and Organs 1 Beyond surface barriers, the immune system operates through a network of billions of white blood cells: Actually, two interacting systems: the innate immune system (first to respond) and the adaptive immune system Cells of the innate immune system: Neutrophils Eosinophils Macrophages Natural killer cells Dendritic cells © McGraw Hill LLC 3  The Immune System: Cells, Tissues, and Organs 2 Cells of the adaptive immune system: Lymphocytes: two main types are T cells and B cells: Have receptors that allow it to recognize one specific antigen. B cells become plasma cells that secrete antibodies. T cells differentiate into helper T cells, killer T cells, or suppressor T cells. B and T cells can mount a rapid and powerful response should they encounter the same invader months or even years in the future. Antigens and antibodies: Substances that trigger the immune response are called antigens and specialized proteins that can recognize and neutralize specific invaders are called antibodies. © McGraw Hill LLC 4  The Immune System: Cells, Tissues, and Organs 3 Inflammatory response: Macrophages engulf the invading microbe and convey danger to other immune system cells: Resulting response causes blood vessels to dilate and fluid to flow out of capillaries into the injured tissue. Pus—dead white blood cells and debris—may collect at the site of infection. © McGraw Hill LLC 5  The Immune System: Cells, Tissues, and Organs 4 Immune response: Phase 1, recognition: Dendritic cells are drawn to the site. Phase 2, proliferation: Helper T cells multiply. Production of killer T and B cells Cytokines: chemical messengers Phase 3, elimination: Killer T cells strike: Cell-mediated immune response Antibody-mediated immune response Phase 4, slowdown: Some memory T and B cells remain. © McGraw Hill LLC 6  Figure 14.1 The immune response. Once invaded by a pathogen, the body mounts a complex series of reactions to destroy the invader. Pictured here are the phases of the immune response as the body works to destroy a virus. Access the text alternative for slide images. © McGraw Hill LLC 7  The Immune System: Cells, Tissues, and Organs 5 Immunity: Usually, after an infection, a person has immunity to the same pathogen. Memory T and B cells continue to circulate in the blood and lymphatic system. Adaptive immunity: immunity to infection acquired by the activation of antigen-specific lymphocytes in response to infection or immunization. © McGraw Hill LLC 8  The Immune System: Cells, Tissues, and Organs 6 Lymphatic system: Vessels that carry lymph; and certain organs and structures: Spleen and lymph nodes Vessels pick up excess fluid from body tissues. This fluid may contain microbes and dead or damaged body cells. As the immune response progresses, a lymph node actively involved in fighting infection may fill with cells and swell. Physicians use the location of swollen lymph nodes as a clue to an infection’s location. © McGraw Hill LLC 9  Immunization 1 Immunization, such as by administering a vaccine, primes the body to remember an encounter with a specific antigen. Some people question whether vaccines do more harm than good, but decreases in vaccination rates can result in outbreaks of dangerous infectious diseases: International travel contributes Types of vaccines: Attenuated organisms Killed viruses A recent advancement in vaccine technology is the messenger RNA (mRNA) vaccine. © McGraw Hill LLC 10  Immunization 2 Vaccine efficacy: In the past century, vaccines have helped increase the average American life span by 30 years. For a small proportion of people, the vaccine does not provoke a strong enough immune response to avoid disease. Keeping vaccination rates consistently high over time is necessary to maintain protection. Vaccines are approved by advisory committees with expert knowledge in virology, microbiology, statistics, epidemiology, and pathogenesis. Strict testing is done before vaccines are licensed. Side effects are rare and usually mild. Any risk must be balanced against the risks of the disease that is prevented. © McGraw Hill LLC 11  Allergy: A Case of Mistaken Identity 1 Allergies are due to an immune system. The immune system reacts to a harmless substance as if it were a harmful pathogen. Allergens elicit an exaggerated immune response: Pollen Animal dander Dust mites and cockroaches Molds and mildew Foods Insect stings © McGraw Hill LLC 12  Allergy: A Case of Mistaken Identity 2 Allergic response: Part of the body’s response is to release large amounts of histamine, a chemical associated with inflammation. In some people, an allergen can trigger an asthma attack. Causes wheezing, tightness in the chest, shortness of breath, and coughing Most serious kind of allergic reaction is anaphylaxis, characterized by swelling of the throat, extremely low blood pressure, fainting, heart arrhythmia, seizures, and sometimes death: Treatment requires immediate injection of epinephrine. © McGraw Hill LLC 13  Allergy: A Case of Mistaken Identity 3 Climate change and allergies: Likely to exacerbate allergies Dealing with allergies: Avoidance Medication Immunotherapy—desensitizing to a particular allergen © McGraw Hill LLC 14  The Spread of Disease: Symptoms and Contagion First phase of infection: the incubation period: May not have symptoms; may be contagious Second and third phases: may “feel a cold coming on”: Symptoms first appear during the prodromal period Many symptoms are due to the immune response. You may be contagious before you have symptoms. Some people can be infected with the flu virus and yet perceive no symptoms. © McGraw Hill LLC 15  The Chain of Infection Links in the chain: (1) Pathogen: Infectious disease cycle begins with a pathogen that enters the body. (2) Reservoir: natural environment of the pathogen. (3) Portal of exit: discharge. (4) Means of transmission: direct and indirect: Vector: carrier of the pathogen from one host to another (5) Portal of entry: skin penetration, inhalation, and ingestion: Pathogens that enter the bloodstream or lymphatic system cause a systemic infection. (6) The new host. Interrupting the chain of infection at any point can prevent disease. Transmission can be disrupted through strategies like hand washing and the use of face masks. Immunization and the treatment of infected hosts can stop the pathogen from multiplying, producing a serious disease, and being passed on to a new host. © McGraw Hill LLC 16  Epidemics and Pandemics 1 Epidemic: a rapidly spreading disease or health-related condition; occurrence is greater than what is normally expected. Pandemic: infectious disease has spread widely Examples: bubonic plague, smallpox, influenza, and Covid-19 Endemic disease: Habitually occurs in a certain region © McGraw Hill LLC 17  Epidemics and Pandemics 2 COVID-19: Outbreak beginning in 2019 Respiratory illness caused by the coronavirus SARS-CoV-2 H1N1 influenza: Outbreak in 2009 Respiratory illness, initially called the swine flu Vaccination recommended for persons aged 6 months to 24 years and those aged 25–64 who are at high risk. © McGraw Hill LLC 18  Pathogens, Diseases, and Treatment: Bacteria 1 Bacteria: microscopic single-celled organisms Pneumonia: an inflammation of the lungs Meningitis: inflammation of the meninges, the protective membranes of the brain, and spinal cord Streptococcus: strep throat and other streptococcal infections Staphylococcus: toxic shock syndrome and other staphylococcal infections: Tuberculosis (TB), which usually affects the lungs Tick-borne infections Other bacterial infections, including ulcers, tetanus, C. diff, pertussis, urinary tract infections (UTIs), and travelers’ diarrhea (TD) © McGraw Hill LLC 19  Figure 14.2 Pathogens and associated infectious diseases. Access the text alternative for slide images. © McGraw Hill LLC 20  Pathogens, Diseases, and Treatment: Bacteria 2 Antibiotic treatments: Antibiotics: drugs that either inhibit the growth of bacteria or kill them The action of antibiotics: Inhibit the synthesis of the bacterial cell wall Interferes with the production of bacterial proteins Inhibit the replication of bacterial DNA Antibiotic resistant bacteria has resulted from overuse and misuse. Proper usage: Don’t take an antibiotic every time you are sick. Use antibiotics as directed. Never take an antibiotic without a prescription. Antibacterial soaps are no more effective than regular soaps and may also be harmful. © McGraw Hill LLC 21  Pathogens, Diseases, and Treatment: Viruses Virus: a microscopic organism that replicates inside the cells of another organism; cause of most contagious diseases: The common cold; influenza, measles, mumps, and rubella. Chickenpox, cold sores, other herpesvirus infections, including the varicella-zoster virus, herpes simplex virus (HSV) types 1 and 2, and Epstein-Barr virus (EBV) Viral hepatitis: HAV, HBV, and HCV Human papillomavirus (HPV) Antiviral drugs are available for some viruses. © McGraw Hill LLC 22  Pathogens, Diseases, and Treatment: Other Pathogens Fungus: an organism that is reproduced by spores: Yeast infections, athlete’s foot, jock itch, and ringworm Protozoa: microscopic single-celled organisms: Malaria Giardiasis Parasitic worms: largest organism that can enter the body to cause infection: Tapeworm, hookworm, and pinworm © McGraw Hill LLC 23  Emerging Infectious Diseases 1 Selected infections of concern: Zika disease Ebola West Nile virus Pathogenic Escherichia coli © McGraw Hill LLC 24  Emerging Infectious Diseases 2 Factors contributing to emerging infections: Drug resistance Poverty Population growth, urbanization, overcrowding, and migration Breakdown of public health measures Travel and commerce Mass food production and distribution Human behaviors Climate change © McGraw Hill LLC 25  Immune Disorders Autoimmune diseases: Immune system targets or destroys specific tissues. Immune system and cancer: Some types of cancer suppress immune responses. © McGraw Hill LLC 26  Supporting Your Immune System General guidelines: Get more sleep. Maintain regular eating patterns. Wash hands frequently. Avoid contact with contagious people. Drink plenty of clean water. Avoid contact with disease carriers such as rodents, mosquitoes, and ticks. Keep vaccinations up to date. © McGraw Hill LLC 27  The Major STIs Sexually transmitted infections (STIs) are spread from person to person mainly through sexual activity. Seven STIs that pose major health threats: HIV/AIDS Chlamydia Gonorrhea Human papillomavirus (HPV) Herpes Hepatitis Syphilis © McGraw Hill LLC 28  HIV and AIDS 1 Human immunodeficiency virus (HIV) causes acquired immunodeficiency syndrome (AIDS). Global HIV epidemic peaked in the late 1990s, at about 3.5 million new infections per year, compared with an estimated 1.5 million new infections in 2020. Youth aged 15–24 represent 16 percent of the global population and one-third of incident HIV infections. In the United States in 2019, 1.2 million people were living with HIV. © McGraw Hill LLC 29  HIV and AIDS 2 HIV infection is a chronic viral infection that progressively damages the body’s immune system. HIV attacks and invades CD4 T-cells, macrophages, and other essential elements of the immune system. It enters a human cell and converts its own genetic material, RNA, into DNA. Viral DNA produces new copies of HIV and reduces immune function: Signaled by the loss of CD4 T cells © McGraw Hill LLC 30  HIV and AIDS 3 AIDS is diagnosed when the number of CD4 cells drops below a certain level: Opportunistic (secondary) infections take hold. Primary infection phase: flu-like symptoms; highly infectious Chronic asymptomatic stage (latency phase): Can last 2–20 years in untreated adults. Virus progressively infects and destroys cells of the immune system. Even if people are symptom-free, people infected with HIV can transmit the disease to others if untreated. © McGraw Hill LLC 31  HIV: Transmitting the Virus HIV lives only within cells and blood and blood products, semen, vaginal and cervical secretions, and breast milk: Cannot live in air, water, or on objects or surfaces. Three primary means of transmission: Specific kinds of sexual contact Direct exposure to infected blood Contact between a woman with HIV and her child during pregnancy, childbirth, breastfeeding, or premastication © McGraw Hill LLC 32  HIV: Key Populations Affected by HIV In 2020, 20 percent of all new HIV diagnoses in the United States were among young people. Young African American and Latino gay and other men who have sex with men were especially affected. Most common means of exposure is sexual activity between men. In the United States, high rates of HIV infection occur in males, certain racial and ethnic groups, and people affected by poverty, discrimination, and substance use disorder. Complex social, economic, and behavioral factors © McGraw Hill LLC 33  Figure 14.3 Routes of HIV transmission among Americans newly diagnosed with HIV infection in 2020. Access the text alternative for slide images. © McGraw Hill LLC SOURCE: Centers for Disease Control and Prevention. 2021. HIV Surveillance Report, vol. 33 (https://www.cdc.gov/hiv/library/reports/hiv-surveillance/vol-33/index.html.) 34  Figure 14.4 What’s risky and what’s not: the approximate relative risk of HIV transmission in various sexual activities. Access the text alternative for slide images. © McGraw Hill LLC 35  HIV: Symptoms Primary HIV infection: flu-like symptoms within a few days or weeks: After these initial symptoms, asymptomatic for the first months or years New symptoms develop as the immune system weakens. Opportunistic infections occur: Pneumocystis pneumonia, a fungal infection. Kaposi’s sarcoma. Frequent and difficult-to-treat vaginal yeast infections in women. Tuberculosis (TB) is increasingly reported. © McGraw Hill LLC 36  HIV: Diagnosis Three general types of diagnostic tests: HIV antibody tests Combination HIV antigen/antibody tests Nucleic acid tests (NATs) If HIV-positive, the next step is to determine the disease’s severity and the viral load is monitored. Certain infections or a severely damaged immune system leads to an AIDS diagnosis. All diagnosed cases of HIV or AIDS must be reported to public health authorities. © McGraw Hill LLC 37  HIV: Treatment Medications can significantly alter the course of the disease and extend life. Antiviral drugs either block HIV from replicating itself or prevent it from infecting other cells: Reverse transcriptase inhibitors, protease inhibitors, integrase inhibitors, and entry inhibitors Drug combinations Antibiotics help prevent opportunistic infections. Postexposure prophylaxis (PEP). Taking the combination drugs is complicated, and side effects may cause people to stop taking them. A person who takes medications as prescribed and achieves HIV suppression to undetectable blood levels has effectively no risk of transmitting HIV to an uninfected partner. © McGraw Hill LLC 38  HIV: Prevention Research into the development of a safe, effective, and inexpensive vaccine is ongoing. How can you protect yourself? Make careful choices about sexual activity. Do not share drug needles. If you have ongoing risk for HIV exposure, consider preexposure prophylaxis (PrEP). Participate in an HIV/STI risk reduction education program. © McGraw Hill LLC 39  Chlamydia Chlamydia is the most prevalent bacterial STI in the United States: Chlamydia trachomatis Infants of women with chlamydia can acquire the infection in the birth canal during delivery: Untreated, can lead to PID and increases the risk of infertility and ectopic (tubal) pregnancy Chlamydia is diagnosed through laboratory tests: Antibiotics are the usual treatment. Testing and treatment for both partners, often using expedited partner therapy. © McGraw Hill LLC 40  Gonorrhea Gonorrhea flourishes in mucous membranes: Neisseria gonorrhoeae Transmitted by sexual contact with the penis, vagina, mouth, or anus of a partner with gonorrhea Often has no symptoms, especially in women Women: pain with urination, increased vaginal discharge, pain or bleeding with intercourse, and lower abdominal pain, and can cause urethritis, cervicitis, and pelvic inflammatory disease (PID) Men: urinary discomfort and discharge from the penis. Infants: gonococcal conjunctivitis Treatment: The current recommended treatment for gonorrhea is ceftriaxone. © McGraw Hill LLC 41  Pelvic Inflammatory Disease Pelvic inflammatory disease (PID) is a major complication of untreated chlamydia or gonorrhea. Initial infection travels beyond the cervix into the uterus, oviducts, ovaries, and pelvic cavity. Leading cause of infertility in young women Symptoms vary: Some are asymptomatic; others have abdominal pain, fever, chills, nausea, vomiting, and abnormal vaginal bleeding. Treatment with antibiotics must be started immediately: Laparoscopy may be used to confirm the diagnosis. Partners must also be treated. © McGraw Hill LLC 42  Human Papillomavirus Human papillomavirus (HPV) can cause several disease, including common warts, genital warts, and genital cancers (virtually all cervical cancers). Most common STI in the United States. More than 80 percent of sexually active people will have been infected by age of 50. Vaccines recommended for girls and boys. Most people have no symptoms and are not aware they are contagious. Treatment: reduction of warts: Regular Pap tests for all women recommended © McGraw Hill LLC 43  Genital Herpes Up to one in eight adults aged 14–49 in the United States has genital herpes. HSV 1 and HSV 2 Symptoms: up to 90 percent have none: Primary outbreak 2–20 days after sex with a partner with HSV: flu-like symptoms, genital lesions. Outbreaks can be triggered by a number of events, including stress, illness, fatigue, sun exposure, sexual intercourse, and menstruation. Antiviral drugs can shorten duration and severity of symptoms. © McGraw Hill LLC 44  Hepatitis A, B, and C 1 Hepatitis is an inflammation of the liver. One type is caused by hepatitis B virus (HBV): Transmission: blood, semen, saliva, urine, and vaginal secretions. Sexual exposure, injection drug use, and nonsexual close contact; and much more contagious than HIV infection. Vaccine is available. Hepatitis A (HAV) is of particular concern for people who engage in anal sex: Vaccine is available. Hepatitis C (HCV) is associated with high-risk sexual encounters. © McGraw Hill LLC 45  Hepatitis A, B, and C 2 Symptoms: Mild cases of hepatitis cause flu-like symptoms such as fever, body aches, chills, and loss of appetite. As the illness progresses, there may be nausea, vomiting, dark-colored urine, abdominal pain, and jaundice. Acute HBV can sometimes be severe, resulting in prolonged illness or death: About 5 percent of adults become chronic carriers, and chronic hepatitis can cause cirrhosis, liver failure, and liver cancer. Diagnosis and treatment: Hepatitis is diagnosed by blood tests used to analyze liver function, detect the infecting organism, and detect antibodies to the virus. There is no cure for HBV and no specific treatment for acute infections. © McGraw Hill LLC 46  Syphilis Syphilis, caused by Treponema pallidum, can now be treated effectively with antibiotics. Usually acquired through sexual contact: Pathogen breaks through openings in the skin or mucous membranes, and syphilis can also pass through the placenta to a developing fetus during pregnancy. Symptoms: Primary syphilis: chancres, 10–90 days post exposure. Secondary syphilis: 3–6 weeks after chancre, body rash. Late or tertiary syphilis: damage to organs, dementia, cardiovascular damage, blindness, and death Treatment: All stages can be treated by antibiotics, but damage from late syphilis can be permanent. © McGraw Hill LLC 47  Other Sexually Transmitted Infections 1 Trichomoniasis, often called trich, is the most prevalent nonviral STI in the United States: Highly transmissible during penile–vaginal sex, while nonsexual transmission is rare. Prompt treatment is important because it may increase the risk of HIV transmission and, in pregnant people, premature delivery. © McGraw Hill LLC 48  Other Sexually Transmitted Infections 2 Bacterial vaginosis (BV): Abnormal vaginal discharge caused by unhealthy vaginal bacteria Pubic lice (crabs) and scabies: Contagious parasitic infections © McGraw Hill LLC 49  What You Can Do about Sexually Transmitted Infections Education Diagnosis and treatment: Be alert for symptoms. Get vaccinated. Get tested. Inform your partners. Get treatment. Prevention: Think and talk about responsible sexual behavior. © McGraw Hill LLC 50  Review 1 Explain the body’s physical and chemical defenses against infection. Describe the step-by-step process by which infectious diseases are transmitted. Identify the major types of pathogens, the diseases they cause, and possible treatments for them. Discuss steps you can take to support your immune system. © McGraw Hill LLC 51  Review 2 Discuss the symptoms, risks, and treatments for the major sexually transmitted infections. List strategies for protecting yourself from sexually transmitted infections. © McGraw Hill LLC 52  Because learning changes everything. ® www.mheducation.com © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC.