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The Health Science Module of the Science & Technology Curriculum Learning and Teaching Resources Theme: Diseases and Community Health Topic: Infectious Diseases & Causes and Prevention of Infectious Diseases The purpose of this set of teaching resources is to provide teachers with some teaching ideas and updated information on individual themes. The content of the topics is built on those in the S1-3 Science Curriculum. It is not expected that every detail in this set of materials is to be covered in class teaching, as some of the materials only serve as references/enrichment for teachers. To enhance the effectiveness of learning and teaching, teachers may need to modify the resources to suit the needs, abilities and interests of their students. Teachers also have to note that the materials included are by no means exhaustive, and should feel free to employ other resources if appropriate. Table of Contents Page Introduction 1 Learning Objectives 1 Scheme of Work 2-6 Lesson Plans 7-13 Teacher/Student Notes Period 1 Period 2 Period 3 Period 4 What are infectious diseases Common diseases transmission routes their 14-15 Why antibiotics should not be used in viral infection 16 Photos of pathogens Microorganisms industry Pasteurization 19 Ultrahigh temperature treatment 19 Lab session 20 Food poisoning and preservation 21 Control infectious diseases 21 Food poisoning 22 The principles of food preservation 22 Entry and defense of infectious agents 23 Transmission of infectious agents 23 Non-specific mechanism of defense against infectious agents 23 Physical barriers and and 14 17-18 the food 19 23-24 Period 5 Period 6 Period 7 Chemical barriers Microbial antagonism The immune system and immunity 26 Steps of immune responses 27 How is immunity developed 28 Vaccines and Vaccination 29 What are vaccines 29 Why do we need vaccines 30 How vaccines work 30 Why multiple vaccine doses 31 Examples of how a vaccine works Control of infectious diseases 33 International Organization 33 Local Organization 34 Roles of health and community workers 34 Implementation of the vaccination program 35 What are advantages and risks of vaccination programs 36 Suggested Activities Lab Safety Precautions Culturing Bacteria Alternative Method of Culturing Bacteria Bacterial Count between Washed and Unwashed Hands Review Questions/quizzes/food for thought Supplementary Resources 24 24-25 31-32 37-40 41 42-43 44 45-46 47 References for Teachers 48 References for Students 48 Causes and Prevention of Infectious Disease Introduction Although our treatment of disease has made much progress in the past decade, our battles against infectious diseases are a never-ending one. New viruses or bacterial outbreaks occur each year. Many of these pathogens are emerging from our technological advanced society. Recent outbreak of West Nile flu in the U.S. is an example of bringing a microbe from one part of the globe to another with the convenience of air traffic. Learning Objectives: After these series of classes, the students will be able to 1. State the difference between bacteria and virus 2. Describe the pasteurization process and identify some food items required microbes for production 3. Recognize the importance of maintaining personal and environmental hygiene 1 Scheme of work for Causes and Prevention of Infectious Diseases Scheme of work for Infectious Diseases (Diseases and Community Health theme ~ Health Science Module) Topic Time I. Infectious Diseases Period 1 Learning Objectives Suggested Activities 1 State the difference between bacteria 1. Video Session . and viruses. Watch the videotape “Louis Resources Teaching Materials 1. Laboratory manual & safety precaution Pasteur’s legacy of hope” from the distributor Barr Media Group, Irwindale, CA, USA 2 Describe some common infectious . diseases and the causative agent. 2. Laboratory Session will be prepared and provided by Biochemistry Department, CUHK 2. Carry out a feasible lab experiment from the suggested topics 3. Discussion Questions How does Dengue fever spread? What is “mad cow” disease? The organization of epidemiological services in Hong Kong. How does Hong 2 (40 mins) Electron microscopic images of bacteria, virus, and fungi will be supplied by Biology Department of CUHK 3. Freeze-fried bacterial culture and other supply can be ordered from commercial source Scheme of work for Causes and Prevention of Infectious Diseases Kong deal with disease outbreak? 4. Homework (beginning at the end of second period and bring completed to third period) Examine the food, environmental, and personal hygiene at home, and try to point out the possible improvements. 3 Scheme of work for Causes and Prevention of Infectious Diseases Scheme of work for Infectious Diseases (Diseases and Community Health theme ~ Health Science Module) Topic I. Infectious Diseases Time Learning Objectives Suggested Activities (40 mins) Resources Period 2 . 1. Explain the process of pasteurization of UHT 2. Identify the use of microorganisms in food manufacturing Scheme of work for Infectious Diseases (Diseases and Community Health theme ~ Health Science Module) Topic Time Learning Objectives Suggested Activities I. Infectious Diseases Period 3 . 1. Understand the importance of personal and environmental hygiene 2. Know the way to avoid food poisoning 3. Know the principles of food preservation 4 (40 mins) Resources Scheme of work for Causes and Prevention of Infectious Diseases Scheme of work for Infectious Diseases (Diseases and Community Health theme ~ Health Science Module) Topic Time II. Infectious Period 4 Diseases Learning Objectives Suggested Activities (40 mins) Resources 1. Explain the mode of entry of infectious agents 2. State the non-specific mechanisms of defense against infectious agents. Scheme of work for Infectious Diseases (Diseases and Community Health theme ~ Health Science Module) Topic Time II. Infectious Period 5 Diseases Learning Objectives Suggested Activities 1. State the function and components of the immune system 2. State what is an immune system 3. Explain what immunity is and how it is developed 5 (40 mins) Resources Scheme of work for Causes and Prevention of Infectious Diseases Scheme of work for Infectious Diseases (Diseases and Community Health theme ~ Health Science Module) Topic Time II. Infectious Period 6 Diseases Learning Objectives Suggested Activities (40 mins) Resources 1. State what vaccines are 2. Describe how vaccines work 3. Explain why booster shots may be necessary for some vaccines Scheme of work for Infectious Diseases (Diseases and Community Health theme ~ Health Science Module) Topic Time II. Infectious Period 7 Diseases Learning Objectives Suggested Activities 1. Identify the international and local organizations involved in the control of infectious diseases 2. Describe how the local immunization is implemented. 3. State the advantages and risks of vaccination programs 6 (40 mins) Resources Lesson Plan for Causes and Prevention of Infectious Diseases Lesson Plans for Infectious Diseases (Diseases and Community Health theme - Health Science Module) Suggestions for teaching and activity sequence with time allocation Lesson 1: What are infectious diseases? Sequence (40 mins) Content and Activity Resources Time Motivation Start by questioning the difference between viral and bacterial infection Teaching notes. <5’ Theme Teaching Illustrate the morphological differences among virus, bacteria, and fungi. Discuss their features according to the following questions below. PowerPoint slides. 15’ What are the common diseases caused by these three microorganisms? Why antibiotics should not be used in viral infection? Why “mad cow” (Bovine Spongiform Encephalopathy, or BSE) disease is different from illness caused by the other microbes? Homework assignment Examine food, environmental, and personal hygiene at home, and try to point out possible improvements. Teaching notes. 5’ Consolidation Discuss the causes of “chicken flu” (H5N1 virus or Avian Influenza) Review 10’ and measures to control its spread. Q&A 7 Lesson Plan for Causes and Prevention of Infectious Diseases Lesson Plans for Infectious Diseases (Diseases and Community Health theme - Health Science Module) Suggestions for teaching and activity sequence with time allocation Lesson 2: Microorganisms and Food – Video and Lab session (40 mins) Sequence Content and Activity Resources Time Motivation Start with providing a yogurt drink (e.g. Yakult) to every student, and Teaching notes. discuss: Yogurt drink What are the microorganisms used in the food industry (e.g. soy sauce, cheese, wine, fermented tofu, etc.)? How the food industry applies pasteurization with the example of fresh milk processing? <10’ Video watching Watch the videotape “Louis Pasteur’s legacy of hope” from the Video tape, Video Player 20’ distributor Barr Media Group, Irwindale, CA, U.S.A. and TV Explain the laboratory safety precautions in the lab and the sequence of the experiment that will be performed Lab manual. Lab session preparation 8 10’ Lesson Plan for Causes and Prevention of Infectious Diseases Lesson Plans for Infectious Diseases (Diseases and Community Health theme - Health Science Module) Suggestions for teaching and activity sequence with time allocation Lesson 3: Food poisoning and preservation Sequence (40 mins) Content and Activity Resources Time 10’ Follow-up Homework and lab discussion (extra time after class is needed for the students to interpret the experiment results under the technician’s supervision) Motivation Ask the students about their experiences of food poisoning Teaching notes. <5’ Theme Teaching Discuss various techniques for food preservation Introduce the principles of food preservation against microorganism growth PowerPoint slides, newspaper 20’ Review and internet 10’ Consolidation How does food poisoning happen? Discuss the food and water supply of HK, and critique its safety monitoring system. Q&A 9 Lesson Plan for Causes and Prevention of Infectious Diseases Lesson Plans for Infectious Diseases (Diseases and Community Health theme - Health Science Module) Suggestions for teaching and activity sequence with time allocation Lesson 4: Pathogens and Defense Against Pathogens Sequence Motivation Theme Teaching (40 mins) Content and Activity Resources 5’ Ask students questions: What infectious diseases you have you had? What infectious diseases do you know? What are the modes of transmission of infectious diseases? What are the physical barriers our body uses to defend against infection? What are the chemical barriers our body uses to defend Time PowerPoint lecture 30’ against infection? Consolidation 5’ Summary Q&A 10 Lesson Plan for Causes and Prevention of Infectious Diseases Lesson Plans for Infectious Diseases (Diseases and Community Health theme - Health Science Module) Suggestions for teaching and activity sequence with time allocation Lesson 5: Immune System and Immunity (40 mins) Sequence Motivation Theme Teaching Consolidation Content and Activity Resources 3’ Ask students question: Do you think physical and chemical defense of our body sufficient to protect us from infectious diseases? Why? What is the immune system? What are the components of the immune system? What are immune response? How is immunity against a disease developed? CD Rom video of immune system and immune response Q&A 11 Time PowerPoint lecture 22’ About Immune System, Corel Medical Series, 1997 15’ Lesson Plan for Causes and Prevention of Infectious Diseases Lesson Plans for Infectious Diseases (Diseases and Community Health theme - Health Science Module) Suggestions for teaching and activity sequence with time allocation Lesson 6: Vaccines and Vaccination Sequence Motivation Theme Teaching Consolidation (40 mins) Content and Activity Resources 5’ Ask students question: What do you remember about your vaccine shots? What are vaccines? How vaccines produced? How do vaccines work? Why are multiple doses of vaccines sometimes needed? Tell the story of Jenner or Salk in the development of vaccination Q&A 12 Time PowerPoint lecture 25’ Printed materials 10’ Lesson Plan for Causes and Prevention of Infectious Diseases Lesson Plans for Infectious Diseases (Diseases and Community Health theme - Health Science Module) Suggestions for teaching and activity sequence with time allocation Lesson 7: Control of Infectious Diseases Sequence Motivation Theme Teaching Content and Activity Resources What are the major international organizations in the control of infectious diseases What are the major local organizations in the control of infectious diseases? What is the value of vaccination in disease control? What are the risks of vaccination? Discussion: Pros and Cons of Vaccination-the lesson from the Whooping cough vaccine 13 Time 5’ Ask students question: Name some of the recent outbreaks of infectious diseases Consolidation (40 mins) PowerPoint lecture 20’ Printed materials Internet 15’ Teacher/Student Notes for Infectious Diseases PERIOD ONE What Are Infectious Diseases? Infectious diseases can be described as a parasitic relationship between microbes and human. The pathogens find the suitable places and conditions in human body to grow, reproduce, and cause damages to the host. Reservoirs of infection are sites where pathogens can reproduce or stay alive until transferring to hosts. The reservoirs can be humans, animals, insects, or arachnids. Humans may contract infection diseases by direct contact, inhalation, ingestion, or injection of the pathogen. Some common diseases in the U.S. are anthrax, rabies, ringworm, salmonellosis, etc. People contract an infectious disease and are capable to transmit the disease to other humans. These people are carriers of the disease, and they may or may not show any symptoms at all. Inanimate reservoirs of infection can be air, soil, food, water, fomites, etc. Common diseases and their transmission routes Transmission Routes Examples Remarks Skin Air Respiratory tract Chickenpox, measles Skin Skin Syphilis, Warts Respiratory tract Respiratory Colds. Influenza tract Shaking hands with a carrier right after his handling of a nose discharge may also contract the pathogen Mouth Gastroenteritis, Hepatitis 14 Consuming food or water contaminated with fecal or soil matters would contract the diseases, and is common in areas hit with natural disasters like flooding. Genital Contact AIDS, Gonorrhea Blood Transfusion AIDS, Hepatitis B Vectors (insects, animal bites) Dengue fever, Rabies Some common infectious diseases in Hong Kong are listed in Table 1. Teacher/Student Notes for Infectious Diseases 15 Teacher/Student Notes for Infectious Diseases Why antibiotics should not be used in viral infection? Antibiotics are designed to control bacteria, but it cannot deter the growth of virus. Antibiotics are designed to attack or inhibit the bacterial structure or enzymes that are absence in viruses. Prescribing antibiotics to viral infection would encourage the growth of antibiotic-resistant bacteria. This resistant strain may be disease causing, and will be hard to contain. Over-prescription of antibiotics has been a major concern lately, because antibiotic-resistant strain of bacteria emerges and antibiotics can no longer contain these bacteria. 16 Teacher/Student Notes for Infectious Diseases ADDITIONAL NOTES FOR TEACHERS Photos of Pathogens Disease causing: Symptoms: Disease causing: Food Poisoning Diarrhea Stomach Ulcer Disease causing: 17 Hepatitis B 18 Teacher/Student Notes for Infectious Diseases Disease causing: Disease causing: Symptoms: Sinusitis Amebiasis Chronic, mild diarrhea with blood and mucus Disease causing: 19 Ascariasis 20 PERIOD TWO Microorganisms And The Food Industry Microbes being used in food production Microorganisms are also used for food production. Lactobacillus is used for sour milk production (e.g. Yakult). The bacteria can partially digest the protein and sugar in milk, so some lactose intolerant individuals may take the pre-treated milk. Bacteria or fungi are also used for cheese flavoring. Yeasts are fungi, and some are being used in food production, such as fermented bean curds, bread, alcohol, etc. Pasteurization Pasteurization is a process that controls the microbe growth by raising the temperature at 71oC for 15 seconds or 62 oC for 30 min followed by dropping the temperature to 4oC in a short period of time. Pasteurization destroys all yeasts, molds, disease-producing bacteria, and over 95% of the less harmful strains of bacteria. The process can preserve the flavor of fresh milk and safe to consume within 2 weeks. Ultrahigh temperature treatment (UHT) Ultrahigh temperature-treated milk is heated to 138 oC for 2 seconds, and it can be stored for a much longer period of time because it is essentially free of microbes. 21 Teacher Notes for Infectious Diseases Lab Session Possible laboratory topics (Please choose the most feasible one, and the topics can be rotated each year) 1. Conducting an experiment on pasteurization using simple equipment in laboratory. A lab technician inoculates bacteria in a culture flask and let it grow overnight. The bacterial count is taken for every 10 oC increase by streaking plates. 2. Performing an experiment on the bacterial count on the hand surface after an outing, before and after hand washing with soap. Thumbs are dipped into a soften agar (beware of the temperature), and incubation until bacterial colonies appear (at least one day). 22 PERIOD THREE Teacher Notes for Infectious Diseases Food Poisoning And Preservation Control infectious diseases Personal hygiene Airborne contamination can be prevented by: covering the mouth and nose when coughing or sneezing, dusting the floor and furniture with a damp cloth, opening the room to fresh air (diluting the pathogen concentration in the air) and sunlight (uv light – killing germs) when somebody has gotten infectious disease. Food hygiene 1. Keeping a clean kitchen (using detergent to clean utensils and kitchen countertops), 2. Avoiding cross-contamination (keeping raw meat or any utensils used for raw meat and cooked food in separate vicinities), 3. Keeping hot foods hot (cooked food always be kept at high temperature), and cold foods cold (avoiding temperature abuse in transport), 4. Washing hands before preparing or eating food. 5. Tap water coming from a contaminated source should be boiled to rid the bacterial spores. The mishandling of food by a caterer may cause food poisoning to a number of people. Thousands of people were affected by food poisoning outbreaks as shown in figure reported by the Department of Health in the years between 1996-2000. Mishandling food in the caterers’ kitchen or in the delivery route may cause these outbreaks. Raw food contamination may 23 also be a factor, such as salmonellosis (caused by salmonella, a disease-causing bacteria, commonly found in eggs). This mishandling may occur in a family setting as well, but the effect is not as noticeable. Environment hygiene Flies and mosquitoes are reservoirs of many common infectious diseases. Keeping the environment clean would eradicate these vectors of disease. 24 Teacher Notes for Infectious Diseases Food poisoning Food poisoning is the diseases caused by the ingestion of contaminants, mostly coming from microbes. The causative agents can be algae (ciguar poison in fish), bacteria, fungi and protozoa. The symptoms can be vomiting and diarrhea, and the incubation period (time from ingestion to the diseased symptom occurred) can be ranged from 1 hour to 4 weeks depending on the type of organism ingested. The principles of food preservation Food preservation uses physical or chemical means to control the growth of microorganisms. Brines are salt solutions with high osmotic pressure that tie up the water availability (example: salted fish). Sugar can be used instead of salt, but the amount required is much greater for a comparable solute concentration in molarity (example: condensed milk). Freezing can preserve some perishable food items; however, it cannot kill the bacterial spores. Acidity (low pH) can be used to control microbe growth (example: pickles). Some chemicals are added for preservation (example: nitrite in ham, bacon, and lunch meat). Other techniques like canning – a process that puts heat sterilized food item in an airtight compartment. Irradiation is a new sterilizing technique that controls the growth of microbes by radiation. 25