Infectious Diseases

1. Infectious Diseases General Principles

2. Slide Index Click on a Subject to Go Directly to That Topic • Overview of Microbes • Bacteria — Prions — Fungi • Viruses — Protozoa • Overview of Infectious Agents and Disease • Food Poisoning — Respiratory Disease • Liver Disease — STD’s • Break the Transmission Cycle • Kill the Infectious Agent • Increase Host Resistance • Active and Passive Immunization • Vaccines • Case Studies: More Information on Specific Diseases

3. What is a Microbe? • Microbes are microscopic organisms that can live almost anywhere. Different microbes have different habitat preferences, ranging from extreme heat to extreme cold. Some microbes need oxygen and some do not. • Most microbes can live in a large variety of habitats, but they can only thrive in a few habitats. • We even have microbes in our bodies--some help us out and some hurt us. You have to have a microscope to see microbes!

4. Where can microbes live? In plants In animals In the dirt All of these A B C D

5. Microbes and Disease • Most microbes belong to one of five categories: bacteria, viruses, prions, protozoa, or fungi. • Some microbes cause disease and some don’t. • Microbes that cause disease are called infectious agents, commonly called “germs” or “bugs.” Infectious agents are microbes that can cause disease.

6. Campylobacter jejuni E. coli Source: NASA Source: cfsan.fda.gov Hepatitis C Virus Source: Amgen, Inc; NIH.gov What Do They Look Like? Infectious agents look different, depending on what class of agent they are Dutch Elm Fungus Source: AGRIC.gov HIV Virus Ciliated Protozoa Source: NLM.gov Source: blm.gov; Wilhelm Foissner

7. Bacteria • Bacteria are prokaryotic, unicellular microbes. • They have their own metabolism. • There are countless numbers of bacteria on the Earth but less than 1% of them cause disease in humans. • Bacteria can live in a vast range of places, but need energy sources to thrive. • Some bacteria produce toxins that can harm us. Bacteria can look like balls, rods, or spirals. Source: NSF.gov

8. Viruses • A virus is a microbe that consists of a nucleic acid housed within a protective coat. • The virus reproduces by hijacking the host cell’s metabolic machinery to replicate its own DNA or RNA. • Most viruses cause disease and are specific as to which type of cell they will attack. Source: niaid.nih.gov

9. Prions • A prion is an infectious particle made from an abnormally folded protein found on the surfaces of neurons. • Prions are highly resistant to heat, UV radiation, and disinfectants. • The best known prion forms holes in brain tissue, making the brain look like Swiss cheese. The prion causes mad cow disease.

10. Protozoa • One celled microbes that can be parasites or predators. • Can live in a variety of places, but prefer moist habitats. • Usually cause disease in humans. • Protozoa are sometimes helpful to other animals. They are a food source for whales and help cows as well as termites digest their food! Protozoa found in human stool samples Source: CDC.gov

11. Fungi • A multi-cellular microbe that is much larger than the other microbes. • Only about 1/2 of all fungi causes disease in humans. • A fungal disease is called a mycose. • Yeast is a fungus that is used to make bread and cheese for us!

12. What Am I? Click on the Buttons to quiz yourself on the various microbes! Word Bank

13. How Can an Infectious Agent Attack Me? • Infectious agents can enter through air, food, water, sexual interactions, skin contact, blood transfusions, etc. • The body’s reaction to an infection can vary from a mild discomfort to death. Infectious Agent

14. Species Specificity I can transmit Brucellosis and Tapeworm • Some infectious diseases of animals can be transferred to humans. • These are called zoonotic diseases. • All mammals can transmit rabies but raccoons and skunks are the most common carriers. We can transmit lots of infectious agents including arenaviruses and hantavirus. I can transmit Ebola virus!

15. Where Else Are Infectious Agents? • Bacteria, protozoa, and fungi all reside in the soil. • Other infectious agents can live on surfaces for hours or even days, like the cold virus.

16. Life Cycle of Infectious Agents • Once a few microbes enter the body, it may take a few hours or days for the agent to reproduce enough to become infectious for others or to cause disease.

17. Can a person transmit an infectious agent before the disease affects him? Yes No

18. Infectious Agents are Deadly • Infectious diseases cause more deaths worldwide than any other single cause. • Infectious diseases account for over 56% of deaths in developing countries. • However, these diseases account for only 8% of deaths in rich countries.

19. Why do more people die from infectious diseases in undeveloped, poor countries than in developed, rich countries? A Poorer countries do not have good vaccination programs. Poorer countries are mostly located in the southern hemisphere where warm temperatures are perfect for infectious agents. B C None of these.

20. What are the Main Types of Infectious Disease? Food Poisoning Respiratory Diseases Liver Diseases Sexually Transmitted Diseases

21. Classical food poisoning is poisoning from foods contaminated with enterotoxins. Bacterial food poisoning is caused by the bacteria itself, not the toxin it produces. Both bacterial and classical food poisoning have similar symptoms. Food Poisoning is a Disease Caused by Infectious Agents

22. Why do you think there was a picture of a hamburger on the previous slide? A Because hamburgers are unhealthy and have lots of fat which poisons us. Because hamburgers are a common place for food poisoning to occur. Because we are talking about food safety so there is a picture of some food. B C

23. Food Poisoning • Classical food poisoning can be prevented by better food storage and handling techniques. • Outbreaks usually occur at picnics, school cafeterias, or anywhere where the food is not handled properly or stored unrefrigerated for a long period of time. Symptoms • nausea • vomiting • abdominal cramps • fever • diarrhea • Botulism-neurologic collapse, respiratory failure, and death. (Caused by improper canning methods)

24. Which Foods are Problem Foods? • Almost all foods can carry infectious agents. • Hamburgers, potato salad, cold cuts, hot dogs, soft cheeses, eggs, and any raw meat are favorite places where microbes can grow and become likely to infect.

25. Respiratory Diseases • Many infectious agents attack the respiratory tract. • The most common respiratory disease is the cold, but others include bronchitis, influenza, SARS, and pneumonia.

26. Liver Diseases • Most liver diseases are caused by a variety of viruses collectively known as hepacivirus. • These viruses cause hepatitis (inflammation of the liver) • You were probably vaccinated for Hepatitis A virus when you were young. Source: consensus.nih.gov A liver with varying stages of hepatitis. The cells on the left are normal liver cells.

27. In the previous slide you learned that many viruses cause hepatitis (aka: inflammation of the liver). What does the “itis” mean? Move your mouse around if an input box does not appear.

28. Microbe Disease Chlamydia Syphilis AIDS Herpes Chlamydia trachomatis Treponema pallidum HIV Herpes Simplex Virus Sexually Transmitted Diseases • STD’s are a result of various viral and bacterial infections that are transmitted through sexual interaction or blood/serum exchange. • There are more than 20 STD’s identified. • The most common are:

29. Acne is an Infectious Disease! • The pimples are dead white blood cells that were attacking bacteria in the skin’s pores. • The sebaceous glands in your skin make an oily substance called sebum. Too much sebum can clog up the hair follicle. This allows bacteria to grow and multiply. • White blood cells rush to the rescue to fight the infection. Acne is not contagious or transferable

30. Different infectious diseases require different approaches for prevention and control. Here are some ideas that apply to most infectious diseases.

31. Three Key Steps reak the cycle of transmission ill the infectious agent ncrease host resistance

32. reak the Cycle of Transmission • Control animals and other biological disease carriers (e.g. insects, rats). • Control air, dust, or dirt that may harbor infectious agents. • Use sanitary practices. • Good personal hygiene • Proper food-handling procedures • Use of protective clothing • Avoid water, foods, animals, and insects likely to transmit disease • Detect disease early and start treatment. • Isolate or limit exposure to infected people. • Use aseptic technique in the management of patients and their excretions and secretions.

33. Controlling Disease Carriers • Sterile males can be used to control insect populations. • Cleaning regularly and picking up trash can keep rodents away. • Sometimes the only way to stop a disease transmission is to kill the carriers. Source: www.lbl.gov Source: USDA

34. Why does introducing sterile males into a population of insects reduce the transmission of infectious agents? It prevents non-sterile males from surviving and reproducing. It indirectly reduces carrier population numbers. Sterile males cannot carry diseases. A B C

35. Infection occurs when you have the infectious agent in or on you and it is injuring you in some way. Contamination occurs when you have the infectious agent in or on you but it is not injuring you. However, it does have the potential to injure others. Contamination Infection versus

36. Are the natural bacteria in your large intestine contaminating you or infecting you? Contaminating Infecting Which is an example of a contaminated person that is not infected? A nauseated doctor (who had her flu vaccine) that had previously helped a man with the flu. A A healthy nurse (who had her flu vaccine) that had previously helped a man with the flu. B

37. Good Sanitary Practices Prevent the Spread of Infection • Wash your hands regularly! • Always keep your area clean and neat! • Be careful around people with infections

38. Why does keeping your area clean and neat help prevent the spread of infection? It helps keep potential disease carriers, like rodents and flies, away. A neat and clean environment is not the best habitat for germs. It helps keep germs from multiplying and creating large populations. All of the Above A B C D

39. Cleanliness = Healthiness • Scrubbing with soap and water eliminates dirt and kills most germs. • Using disinfectant provides an extra margin of safety. • The biggest place for germs to reside in your house is in the kitchen.

40. Click on a button to see the best places for infectious agents to reside! The cafeteria is a great place for germs to hide. The food that sits out for hours unheated or cooled is a perfect breeding ground for bacteria. The cafeteria is a great place for germs to hide. The food that sits out for hours unheated or cooled is a perfect breeding ground for bacteria. The cafeteria is a great place for germs to hide. The food that sits out for hours unheated or cooled is a perfect breeding ground for bacteria. Cafeteria Playground Teacher’s Desk Classroom Germs absolutely love the bathroom! Many diseases are spread through human feces. Always wash your hands!!! Germs absolutely love the bathroom! Many diseases are spread through human feces. Always wash your hands!!! Germs absolutely love the bathroom! Many diseases are spread through human feces. Always wash your hands!!! Bathrooms The playground isn’t just a fun place for you! Infectious agents can live in the soil and on the bars. Any germs on your hands will transfer to the bars and to the next person who plays on them. The playground isn’t just a fun place for you! Infectious agents can live in the soil and on the bars. Any germs on your hands will transfer to the bars and to the next person who plays on them.

41. What are the Best Disinfectants Disinfectant Strength Enveloped Non-Enveloped Bacteria FungiViruses Viruses Low Good Good Good Good Chlorox Bleach Iodine Alcohol Chlorhexidine QuaternaryAmmonia Low Good Fair Good Good Low Good Good Fair Good Low Poor Good Fair Good Low Poor Good Fair Fair All of these are low level in strength but anything higher is not necessary for everyday use.

42. Based upon the previous slide, which disinfectant is the best one to use? Chlorox Bleach Iodine Alcohol Chlorhexidine Quaternary Ammonia

43. Washing Your Hands Fun Statistics About Washing Your Hands: 1. A study of 305 Detroit students found that washing their hands 4 times a day reduced their sick days due to respiratory illnesses by 24% and stomach flues by 51%. 2. 1 out of every 3 people do not wash their hands after using the bathroom. • Washing your hands is the most important thing you can do to keep from getting sick! • You pick up germs and infect yourself by touching your nose, eyes, and mouth. • The spread of the cold, hepatitis A, meningitis, and diarrhea can all be prevented by washing your hands. Source: foodsafety.gov

44. How long should you scrub your hands when washing them? 0-10 seconds 15-30 seconds 1-2 minutes A B C

45. Why does touching your nose, eyes, and mouth get you sick if you haven’t washed your hands? Because your nose, eyes, and mouth have mucous membranes that easily transfer infectious agents from your hands to the rest of your body. Because your nose, eyes, and mouth have no resistance to infectious agents so infection is a sure thing. A B

46. Food Preparation • Many deadly infectious agents live in our food. • Always clean your area before and after cooking, especially when cooking raw meat. • Always cook food well and keep foods refrigerated.

47. The All Important Refrigerator • Keeping foods cold is even more important than cooking them. • Cold temperatures keep infectious agents from multiplying and growing. • Always refrigerate foods within two hours of cooking. • Keep foods at or below 40°F.

48. Why does cooking food help prevent infectious disease? A Cooking food prevents infectious agents from growing and multiplying Cooking food kills infectious agents B

49. Isolate the Disease • The key to blocking the transmission of infection is to isolate the disease. • Volunteer isolation and quarantine are the best ways to prevent the spread of disease. • Public authorities must act quickly to prevent outbreaks from becoming epidemics. This card was posted outside the house of a person who had scarlet fever. The authorities quarantined him to prevent the spread of infection. Source: National Library of Medicine

50. Problems with Isolation • Most people do not want to voluntarily quarantine themselves. • Mass transit allows an easy route for an infectious disease to spread.