Human Diseases, 8th Edition - Chapter 3

Chapter 3: Infectious Diseases CHAPTER OVERVIEW Introductory terms related to the principles of infectious diseases are introduced. Infectious disease transmission routes are reviewed. Topics related to controlling infectious diseases are presented. Pathogenic microorganisms are listed and introduced. Treatments for infectious diseases are discussed. Vaccine-preventable infectious diseases are presented. TRANSITION GUIDE/NEW TO THE EIGHTH EDITION Chapter reviewed to ensure accuracy and to include any updates or changes in chapter content. Included content on infection control and nosocomial infections. Expanded the Diseases at a Glance section at the end of the chapter. Updated and reviewed the professional references at the end of the chapter. CHAPTER OUTLINE Introduction Principles of Infectious Disease Transmission of Infectious Diseases Nosocomial Infections Control of Infectious Diseases Bloodborne Pathogens Survey of Pathogenic Microorganisms Viruses Bacteria Protozoa Fungi Helminths Prions Treatment of Infectious Diseases Emerging and Reemerging Infectious Diseases Common Vaccine-Preventable Childhood Infectious Diseases CHAPTER OBJECTIVES Define infectious disease and its terminology Explain how infectious diseases are transmitted Describe and compare the characteristics of prions, viruses, bacteria, protozoa, fungi, and helminths Define nosocomial infections Explain treatment for bacterial, viral, fungal, and parasitic infectious diseases Understand the appropriate use of antibiotics and explain the problem of antibiotic resistance Describe examples and causes of emerging and reemerging infectious diseases Identify common childhood vaccine-preventable infectious diseases INSTRUCTIONAL GOALS Objective 1: Define infectious disease and its terminology. Utilize the PowerPoint presentations as a starting point for your lecture. Utilize one or more of the Classroom Activities to augment the chapter and student learning. (A list of the Classroom Activities and instructions can be found in the preface of the Instructor's Manual.) Choose a Classroom Activity using Table 3-1. Objective 2: Explain how infectious diseases are transmitted. Utilize the PowerPoint presentations as a starting point for your lecture. Review the feature Prevention PLUS!: Handwashing. Utilize one or more of the Classroom Activities to augment the chapter and student learning. (A list of the Classroom Activities and instructions can be found in the preface of the Instructor's Manual.) Choose a Classroom Activity using Table 3-2. Objective 3: Describe and compare the characteristics of prions, viruses, bacteria, protozoa, fungi, and helminths. Utilize the PowerPoint presentations as a starting point for your lecture. Review the feature Prevention PLUS!: Advice for Travelers. Objective 4: Define nosocomial infections. Utilize the PowerPoint presentations as a starting point for your lecture. Objective 5: Explain treatment for bacterial, viral, fungal, and parasitic infectious diseases. Utilize the PowerPoint presentations as a starting point for your lecture. Objective 6: Understand the appropriate use of antibiotics and explain the problem of antibiotic resistance. Utilize the PowerPoint presentations as a starting point for your lecture. Objective 7: Describe examples and causes of emerging and reemerging infectious diseases. Utilize the PowerPoint presentations as a starting point for your lecture. Utilize one or more of the Classroom Activities to augment the chapter and student learning. (A list of the Classroom Activities and instructions can be found in the preface of the Instructor's Manual.) Choose a Classroom Activity using Tables 3-3 and 3-4. Objective 8: Identify common childhood vaccine-preventable infectious diseases. Utilize the PowerPoint presentations as a starting point for your lecture. WORKSHEET 1: Define the Terms amoeboids antibiotic resistance antibiotics ascaris bacilli cell walls chitin cilia ciliates communicable contagious disinfection emerging infectious diseases endemic endotoxin epidemiology flagellates gram stain hookworms horizontal transmission incidence infectious diseases infestations latent infection microbiota mycelia mycoses normal flora nosocomial notifiable diseases nucleic acid analogues outbreak pandemic parenteral pathogen prevalence prion pseudopodia quarantine reemerging infectious diseases reservoir spirilla spirochetes spores sporozoans vertical transmission vibrios WORKSHEET 2: Testbank Questions and Answers 3.1 Multiple-Choice Questions 1) A pathogen is a _____. A) disease-causing microorganism B) disease always present within a population C) prion, composed only of proteins D) specialist in the study of disease Answer: A Objective 1 2) The word _____ is derived from Greek words that mean "to cause suffering." A) contagious B) disease C) infection D) pathogen Answer: D Objective 1 3) Infectious diseases transmitted directly by human contact are said to be _____. A) contagious or communicable B) endemic or epidemic C) horizontal or vertical D) incidence or prevalence Answer: A Objective 1 4) Tracking the _____ of a disease is tracking the number of new cases of a disease in a population. A) incidence B) outbreak C) pandemic D) prevalence Answer: A Objective 1 5) When a disease always occurs at low levels in a population, it is said to be _____. A) endemic B) epidemic C) pandemic D) pathodemic Answer: A Objective 1 6) People who harbor infectious disease but do not have signs or symptoms are known as _____. A) carriers B) fomites C) prions D) reservoir Answer: D Objective 2 7) _____ transmission describes transmission of an infectious disease from a reservoir to a susceptible human. A) Diagonal B) Horizontal C) Oblique D) Vertical Answer: B Objective 2 8) _____ transmission of an infectious disease occurs when an individual is infected by contact with the reservoir. A) Direct horizontal B) Direct vertical C) Indirect horizontal D) Indirect vertical Answer: A Objective 2 9) _____ transmission of an infectious disease occurs when a pathogen can withstand the environment outside of its host for a long period of time before infecting another individual. A) Direct horizontal B) Direct vertical C) Indirect horizontal D) Indirect vertical Answer: B Objective 2 10) Intravenous drug users who share needles can transmit infectious diseases like hepatitis B, hepatitis C, and HIV via _____ contact. direct horizontal indirect vertical Answer: A Objective 2 11) Diseases that are transmitted primarily by _____ contact include ringworm, HIV/AIDS, the common cold, and influenza. A) direct B) horizontal C) indirect D) vertical Answer: A Objective 2 12) The most common type of nosocomial infections are _____. A) bloodstream infections B) respiratory infections C) surgical site infections D) urinary tract infections Answer: D Objective 4 13) A weakened patient, such as one with a weakened immune system, is an ideal target for an _____ pathogen. A) emerging B) isolation C) opportunistic D) reemerging Answer: C Objective 2 14) The principle route of transmission of _____ are contact with healthcare staff, contact with contaminated instruments, and through the hospital’s ventilation system A) cilia B) endemic C) microbiota D) nosocomial Answer: D Objective 4 15) Normal flora _____. A) always cause disease and are highly contagious B) are used to develop drugs used to fight infections C) do not harm us and in some cases help us D) have diagnostic principles to help identify disease Answer: C Objective 4 16) _____ of infected persons in hospitals, such as a person with influenza remains home in bed, can be an effective way to control infectious diseases. A) Disinfection B) Isolation C) Infestation D) Quarantine Answer: B Objective 2 17) _____ is the separation of persons who may or may not be infected from healthy people until the period of infectious risk is passed. A) Disinfection B) Isolation C) Infestation D) Quarantine Answer: D Objective 2 18) _____ of potentially infectious materials, like surfaces in patient's rooms and linens, is necessary to prevent transmission. A) Disinfection B) Isolation C) Infestation D) Quarantine Answer: A Objective 2 19) _____ etiquette controls the spread of influenza, cold, tuberculosis, and other pulmonary disease. A) Cardiac D) Digestive C) Respiratory D) Urinary Answer: C Objective 2 20) Of all methods, _____ may be the most effective way to protect personal and public health from infectious diseases, such as the elimination of smallpox. A) antibiotics B) fomites C) nosocomials D) vaccinations Answer: D Objective 2 21) The _____ estimates that 5.6 million healthcare workers in the United States are at risk work-related exposure to bloodborne pathogens. A) Centers for Disease Control and Prevention B) Department of Health and Human Services C) Occupational Safety and Health Administration D) World Health Organization Answer: C Objective 2 22) Where bloodborne pathogens are likely to be encountered, a workplace must adopt the practice of _____. A) Isolation Techniques B) Quarantine Precautions C) Standard Precautions D) Sterilization Standards Answer: C Objective 2 23) A _____ is an infectious agent composed only of proteins. A) bacteria B) capsid C) prion D) virus Answer: C Objective 3 24) Viruses are infectious particles with a core of genetic material wrapped in a _____. A) bacteria B) capsid C) prion D) virus Answer: B Objective 3 25) _____ must carry out their life processes by entering cells and directing the cell's energy, materials, and organelles. A) Bacteria B) Capsid C) Prion D) Virus Answer: D Objective 3 26) Some viruses cause infected cells to _____, or rupture, as when HIV infects and reproduces within T cells. A) disinfect B) lyse C) reservoir D) spore Answer: B Objective 3 27) The human papillomavirus is linked to _____ cancer. A) brain B) cervical C) skin D) thyroid Answer: B Objective 5 28) Bacteria that have spherical (round) shapes are called _____. A) bacilli B) cocci C) spirochetes D) vibrios Answer: B Objective 3 29) During the gram stain process, _____. A) thick-walled cells turn orange and thin-walled cells become yellow B) thick-walled cells turn pink and thin-walled cells become purple C) thick-walled cells turn purple and thin-walled cells become pink D) thick-walled cells turn yellow and thin-walled cells become orange Answer: C Objective 3 30) Protozoa are _____. A) much larger than bacteria B) much larger than viruses C) much smaller than bacteria D) much smaller than viruses Answer: D Objective 3 31) One classification of protozoa move by means of numerous hairlike projections called _____. A) cilia B) flagellates C) mycelia D) spores Answer: A Objective 3 32) Some species of bacteria produce _____ that permit these bacteria to survive drying, lack of nutrients, and harsh conditions such as extreme heat. A) capsid B) cilia C) endospores D) prion Answer: C Objective 3 33) Fungal infections are known as _____. A) chitins B) mycoses C) pseudopodia D) spirochetes Answer: D Objective 3 34) Pneumocystis jirovecii causes an opportunistic form of pneumonia, one of the diagnostic indicator diseases for _____ A) AIDS B) HBV C) IgG D) SLE Answer: A Objective 3 35) Penicillin and related drugs act on _____. A) the cell nucleus and are especially useful in controlling gram-negative viruses B) the cell nucleus and are especially useful in controlling gram-positive viruses C) the cell wall and are especially useful in controlling gram-negative bacteria D) the cell wall and are especially useful in controlling gram-positive bacteria Answer: D Objective 5 36) Antibiotic resistance plays an important role in the increased incidence of _____ infections. A) bacterial B) fungual C) protozoan D) viral Answer: A Objective 5 37) Antifungal drugs target fungal _____. A) cell nuclei B) cell organelles C) DNA and RNA D) walls and membranes Answer: D Objective 6 38) _____ is a highly contagious disease caused by the rubeola virus. A) Measles B) Mumps C) Rubella D) Tetanus Answer: A Objective 8 39) _____ is caused by the paramyxovirus. A) Measles B) Mumps C) Rubella D) Tetanus Answer: B Objective 8 40) Rubella (German measles) is caused by the rubella _____. A) bacteria B) fungi C) protozoan D) virus Answer: A Objective 8 3.2 True/False Questions 1) The number of existing cases of a disease is known as its incidence. Answer: False Objective 1 2) If a disease occurs in unusually large numbers over a specific area, it is said to be epidemic. Answer: True Objective 1 3) The source of an infectious agent is known as a reservoir. Answer: True Objective 2 4) Vertical transmission of infectious diseases can occur either directly or indirectly. Answer: False Objective 2 5) Transmission by direct contact also occurs when infectious agents are expelled in droplets produced by sneezing or coughing. Answer: True Objective 2 6) Contaminated inanimate objects are called fomites, and these can also transmit infection. Answer: True Objective 2 7) Food and beverages can transmit infectious disease, such as through the fecal–oral route. Answer: True Objective 2 8) Punctures, injections, bites, and surgery that allow microorganisms to be deposited directly into the tissue below the skin is known as the parenteral route of infection. Answer: True Objective 2 9) Healthcare facilities are a major reservoir for opportunistic pathogens that can cause nosocomial infections. Answer: True Objective 4 10) Normal flora microorganisms may become harmful and become opportunistic pathogens. Answer: True Objective 2 11) Handwashing prevents foodborne illnesses as well as those transmitted by respiratory droplets. Answer: True Objective 2 12) Healthcare workers who have antibodies to HBV either from preexposure vaccination or prior infection are not at risk for contracting Hepatitis B. Answer: True Objective 2 13) The average risk of HIV infection after needlestick exposure or cut exposure to HIV-infected blood is 0.3%. Answer: True Objective 2 14) The World Health Organization Pathogens Standard is aimed at protecting healthcare workers from exposure to and infection by bloodborne pathogens. Answer: False Objective 2 15) Prion diseases usually progress rapidly and are currently untreatable and fatal. Answer: True Objective 3 16) Viruses are not considered living organisms because they do not independently grow, metabolize, or reproduce. Answer: True Objective 3 17) Bacteria are microscopic, single-celled organisms. Answer: True Objective 3 18) Bacteria that are comma-shaped are called vibrios. Answer: True Objective 3 19) Protozoa are single-celled eukaryotic microorganisms. Answer: True Objective 3 20) Fungi can be single-celled or multi-celled organisms. Answer: True Objective 3 21) Viral infections can be treated with a variety of antibiotics. Answer: False Objective 5 22) Antibiotic resistance arises when bacteria adapt to antibiotics. Answer: True Objective 6 23) Some antiviral drugs act as nucleic acid analogues, substances that mimic DNA or RNA bases. Answer: True Objective 6 24) Treatment for systemic fungual infections entail risky side effects. Answer: True Objective 6 25) There are certain antibiotics that may be used to treat protozoal infections. Answer: True Objective 6 3.3 Short-Answer Questions 1) Infectious diseases are caused by microorganisms called _____. Answer: pathogens Objective 1 2) _____ is the study of the transmission, occurrence, distribution, and control of disease. Answer: Epidemiology Objective 1 3) When an epidemic has spread to include several areas worldwide, it is said to be _____. Answer: pandemic Objective 1 4) When a disease suddenly occurs in unexpected numbers in a limited area and then subsides, this is described as an _____. Answer: outbreak Objective 1 5) _____ diseases are certain infectious diseases that physicians must report to the Centers for Disease Control and Prevention. Answer: Notifiable Objective 1 6) An example of a _____ transmission of an infectious disease is one that is transmitted to newborns from infected mothers. Answer: vertical Objective 2 7) The _____ tract is the most frequently used portal of entry for pathogens. Answer: respiratory Objective 2 8) _____ or hospital-acquired infections are infections acquired in a healthcare facility. Answer: Nosocomial Objective 4 9) The 100 trillion microorganisms that are commonly present in or on our bodies comprise our normal flora or _____. Answer: microbiota Objective 2 10) According to the Centers for Disease Control and Prevention, _____ is the single most important means of preventing the spread of nosocomial infections. Answer: handwashing Objective 2 11) Some viruses sustain a _____ infection, whereby they insert themselves into cells and later a trigger activates the virus. Answer: latent Objective 3 12) Bacteria have _____, a rigid layer or organic material surrounding their delicate cell membranes. Answer: cell walls Objective 3 13) Bacteria that have rod-shaped cells are called _____. Answer: bacilli Objective 3 14) Bacteria that have corkscrew-shaped cells are called _____. Answer: spirochetes Objective 3 15) Bacteria that have spiral-shaped cells are called _____. Answer: spirilla Objective 3 16) Thickness and chemical composition of the cell wall accounts for the way certain cells stain during the _____ stain procedure. Answer: gram Objective 3 17) Some bacteria have a particularly potent toxin, called an _____, that causes life-threatening shock. Answer: endotoxin Objective 3 18) Types of _____ are described as amoeboids, flagellates, ciliates, and sporozoans. Answer: protozoa Objective 3 19) Amoeboids move by a means of cell membrane extensions called _____ (from Greek words meaning "false feet"). Answer: pseudopodia Objective 3 20) Fungi use specialized filaments called _____ to absorb nutrients from their surroundings. Answer: mycelia Objective 3 21) _____ are parasitic worms and are complex multicellular motile organisms. Answer: Helminths Objective 3 22) Many helminths have evolved complex life cycles and strategies for infecting new hosts. Infections with helminths are often called _____. Answer: infestations Objective 3 23) The effective treatment of an infectious disease depends on the type of causative _____. Answer: pathogen Objective 6 24) _____ infectious diseases include outbreaks of previously unknown diseases or known diseases whose incidence in humans has significantly increased in the past two decades. Answer: Emerging Objective 7 25) _____ infectious diseases are known diseases that have reappeared after a significant decline in incidence. Answer: Reemerging Objective 7 WORKSHEET 3: Discussion Questions and Answers 3.4 Discussion Questions 1. Define and explain the differences between incidence and prevalence. Answer: The incidence of a disease is the number of new cases of a disease in a population. Tracking incidences, patterns are revealed, as when influenza incidences increase in winter. Prevalence is the number of existing cases of a disease, which tells how significant the disease is in a certain population. 2. Define and explain the differences between endemic, epidemic, and pandemic. Answer: When a disease always occurs at low levels in a population, that disease is said to be endemic. Sexually transmitted diseases are endemic diseases. If a disease occurs in unusually large numbers over a specific area, it is said to be epidemic. Influenza occurs as an epidemic. When an epidemic has spread to include several areas worldwide, it is said to be pandemic. HIV/AIDS is considered to be pandemic. 3. Define and explain the differences between horizontal transmission and vertical transmission. Answer: Horizontal transmission describes transmission of an infectious disease from a reservoir to a susceptible human. Examples include kissing, engaging in sexual contact, or being bitten by an infected animal or insect. Vertical transmission are infectious diseases that are transmitted from one generation to the next, as when syphilis, HIV/AIDS, or ophthalmia neonatorum are transmitted to newborns from infected mothers. 4. Explain why healthcare facilities are a major reservoir for pathogens. Answer: A weakened patient is an ideal target for an opportunistic pathogen. A patient's resistance to an infection can be reduced as a result of disease or compromised immunity. Burns, surgical wounds, injections, invasive diagnostic procedures, ventilators, intravenous therapy, and catheters increase the risk of infection. The principal routes of nosocomial infections are contact with healthcare staff, contaminated instruments, and through a hospital’s ventilation system. 5. Give a brief description of prions, viruses, and bacteria. Answer: Prions are infectious agents composed of only proteins. All known prion diseases affect the structure of the brain or other neural tissue. Viruses are infectious particles with a core of genetic material (either RNA or DNA) wrapped in a protein coat called a capsid. Viruses are not considered living organisms because they do not independently grow, metabolize, or reproduce. Bacteria are single-celled organisms with no nucleus or membranous organelles. There are many different forms of bacteria, such as bacilli, spirilla, spirochetes, or vibrios. 6. Give a brief description of protozoa, fungi, and helminths. Answer: Protozoa are single-celled, nucleus-containing microorganisms. Protozoa are much larger than bacteria and have complex internal structures. Types of protozoa include amoeboids, flagellates, ciliates, and sporozoans. Fungi can be single-celled or multi-celled organisms. They have a reproductive structure bearing spores, which are known allergens. Fungal infections are known as mycoses. Many mycoses are opportunistic infections. Helminths are parasitic worms and are complex, multicellular organisms. They often have well-developed reproductive systems capable of producing large numbers of offspring. Infections with helminths are often called infestations. 7. There are multiple, common childhood, vaccine-preventable infectious diseases. Of the 10, name three and describe how they are commonly spread. Answers: Measles, caused by rubeola virus, is spread by respiratory droplets or airborne transmission. Mumps is caused by the paramyxovirus and is spread with respiratory secretions or saliva through fomites. Rubella (German measles) is caused by the rubella virus. It is highly contagious and is spread by respiratory droplets, airborne transmission, or transmitted from a woman to her fetus. Whooping cough is a highly contagious bacterial infection caused by Bordetella pertussis. The bacteria are spread by contact with respiratory droplets. Diphtheria is a highly contagious bacterial disease caused by Corynebacterium diptheriae, which is primarily spread by respiratory droplets; transmission by fomites is rare. Tetanus is a bacterial infection caused by Clostridium tetani. The bacteria are found in contaminated soil and animal excrement and enter the body via wounds. Chickenpox is a contagious viral infection caused by the varicella zoster virus. The virus is spread by direct contact, droplet transmission, and airborne transmission. Haemophilus influenzae type b is a bacterium spread by respiratory droplets. Poliomyelitis is caused by the polio virus. Transmission occurs either by person-to-person or by contact with infectious saliva or feces or contaminated sewage or water. Streptococcus pneumoniae is a bacterium that is transmitted by respiratory droplets.