Chapter 4 Preventing Disease Transmission KNOWLEDGE OBJECTIVES 1. Describe how the immune system works. 2. Identify four ways in which diseases are transmitted, and give an example of how each can occur. 3. Describe the four conditions that must be present for disease transmission. 4. Identify how each of the following infectious diseases is transmitted: Hepatitis A+ Hepatitis B (HBV) Herpes Meningitis 5. Identify at least six basic universal precautions for protecting yourself against infectious diseases. 6. Describe the procedure a first responder would use to disinfect equipment and work surfaces, clothing, and leather goods. 7. Explain the importance of documenting an exposure to an infectious disease and postexposure follow-up care. 8. Discuss how the guidelines for bloodborne pathogens influence your actions as a first responder. 9. Define the key terms for this chapter. Tuberculosis Human immunodeficiency virus (HIV) 31
OUTLINE Introduction 53 How Infections Occur 53 Disease-Causing Agents 53 The Body's Natural Defences 54 How Diseases Spread 55 Diseases That Cause Concern 56 Herpes 56 Meningitis 58 Tuberculosis 58 Hepatitis 58 HIV 53 Other Diseases and Immunization 60 Protecting Yourself From Disease Transmission 60 Precautions 60 The Exposure Control Plan 65 If an Exposure Occurs 66 KEY POINTS Diseases HIV. Tuberculosis. Herpes. Meningitis. Conditions Necessary for Disease Transmission Pathogen. Quantity. Susceptibility. Entry Site. How Pathogens Enter the Body Direct contact. Indirect contact. Airborne. Vector-borne. Exposure Control Plan Exposure determination. Identification of who will receive training, protective equipment, and vaccination. Procedures for evaluating exposures. Precautions and Guidelines to Prevent Disease Transmission Protective equipment. Personal hygiene practice. Engineering controls. Work practice controls. 32
LEARNING ACTIVITIES Matching Match each term with its definition. Write its letter on the line in front of the definition. Terms a. Antibody b. Immunization c. Hepatitis d. Pathogen e. Virus Definitions 1. A substance introduced into the body to build resistance to a specific infection 2. A disease-causing agent, also called a germ 3. A disease-causing agent that requires another organism to live and reproduce 4. An infection-fighting protein released by white blood cells 5. A viral infection of the liver Short Answer Read each statement or question and write the correct answer or answers in the space provided. 1. List the four conditions that must be present for a disease to be transmitted from one person to another. 1. 2. 3. 4. 2. If your equipment became contaminated with blood or other body fluids, what type of solution would you use to disinfect it? 3. List six precautions you can take to prevent disease transmission. 1. 2. 3. 4. 5. 6. 33
CASE STUDY Read the case study and answer the questions that follow. Case 4.1 You are called to a scene where a young boy has been bitten by a stray dog. The boy has two bleeding puncture wounds on the posterior side of his left leg, distal to the knee. The bleeding is easily controlled by applying pressure to the wound. 1. The transmission of any infection that might result from the dog bite is best described as a. Direct contact transmission. b. Indirect contact transmission. c. Airborne transmission. d. Vector-borne transmission. 2. T F In caring for this casualty and being exposed to his blood, you are at significant risk of infection for any diseases that might have been transmitted to the boy through the dog bite. 3. What disease might this dog transmit to the boy? 4. Which of the following protective items should you wear as you control the bleeding? a. Disposable gloves b. Protective eye wear c. Disposable mask d. All of the above 34
SELF-ASSESSMENT Circle the letter of the best answer. 1. Pathogens that depend on another living organism to live and reproduce are a. Bacteria. b. Protozoa. c. Viruses. d. Fungi. 2. Disease transmission from a casualty to a first responder requires four conditions. Which of the following is one of these four? a. The casualty requiring care must be infected with the disease. b. The first responder providing care must be exposed to the infected casualty's body fluids. c. There must be enough body fluid that contains the pathogen to cause infection. d. All of the above. 3. Basic components of the immune system are a. Red blood cells. b. White blood cells. 4. Through which route is the herpes pathogen transmitted? a. Direct contact b. Indirect contact c. Airborne transmission d. All of the above 5. Which of the following protective equipment should a first responder wear to prevent transmission of disease when handling and cleaning equipment contaminated with blood? a. Protective eye wear b. Disposable mask c. Disposable gloves d. a and c 6. Approximately how much household chlorine bleach is needed in 4 litres of water to produce an effective solution for disinfecting emergency care equipment such as splints and stethoscopes? a. 65 ml b. 125 ml c. 250 ml d. 500 ml c. Platelets. d. Serum. 35
7. You think you have been exposed to an infectious disease while providing care. You would first a. Try to find out which disease it was. b. Notify your superior and any involved medical personnel. c. Go to be tested at a hospital. d. All of the above. 8. In which of the following ways can a pathogen enter the body? a. Direct contact transmission b. Indirect contact transmission c. Airborne transmission d. All of the above 9. Jaundice is a condition caused by illness affecting the a. Liver. b. Heart. c. Brain. d. Spleen. 10. The infectious disease most likely to be transmitted by contaminated shellfish is a. Tuberculosis. b. Meningitis. c. Hepatitis A. 11. Which of the following infectious diseases might be transmitted to a first responder during unprotected rescue breathing or suctioning? a. Lyme disease. b. Bacterial meningitis. c. Rocky Mountain spotted fever. d. All of the above. 12. HIV is known to be transmitted through exposure to all of the following infected products EXCEPT: a. Blood. b. Saliva. c. Semen. d. Breast milk. 13. If you suspect you have been exposed to infected blood or other body fluids during emergency care, the first step you should take is to: a. Document the situation in which the exposure occurred. b. Clean and disinfect all your contaminated equipment. c. Wash the area of contact with soap and water. d. Contact your medical director or physician for advice. d. Chlamydia. 36
14. Characteristic signs of an active herpes infection are a. Hives. b. Yellowish skin colour. c. Blisterlike sores. d. Reddened, watering eyes. 15. The body system most commonly affected by tuberculosis is the a. Circulatory system. b. Integumentary system. c. Nervous system. d. Respiratory system. 16. Which of the following diseases can be transmitted by individuals who show no apparent sign of the disease? a. Hepatitis B. b. HIV/AIDS. c. Tuberculosis. d. All of the above. 37
Answers to Exercises Unit 4-Preventing Disease Transmission Matching: 1. b 2. d 3. e 4. a 5. c. Short Answer: 1. A pathogen the pathogen is in sufficient quantity to cause disease; a person is susceptible to the pathogen; the pathogen is transmitted through the correct entry site. 2. A solution of 1/4 cup of common household chlorine bleach in a gallon of water. 3. Wear disposable gloves; wash hands thoroughly after providing care; use resuscitation devices; clean and disinfect all equipment and work surfaces possibly contaminated by blood or other body fluids; wear protective coverings, such as a mask, eyewear, and gown; place sharp items in punctureresistant containers; discard gloves that are peeling, discoloured, torn, or punctured; change gloves between contacts, and avoid handling items; cover any cuts, scrapes, or skin irritations you may have by wearing protective body clothing and/or bandages; avoid eating, drinking, and touching your mouth, nose, or eyes while providing care or before washing hands; avoid needle stick injuries by not attempting to bend or recap any needles; place all contaminated clothing in wellmarked plastic bags for disposal or washing. Case Study 4.1: 1. d 2. F 3. Rabies 4. a. Self-Assessment: 1. c (Pg. 54) 2. d (Pg. 55) 3. b (Pg. 54) 4. a (Pg. 57) 5. c (Pg. 62) 6. a (Pg. 64) 7. b (Pg. 66) 8. d (Pg. 56) 9. a (Pg. 58) 10. c (Pg. 58) 11. b (Pg. 57) 12. b (Pg. 57) 13. c (Pg. 66) 14. c (Pg.??) 15. d (Pg.??) 16. d (Pg.??) 38