Name____________________________________________ Ms. Sameroff Objective: Class__________ Date______________ SWBAT describe what causes infectious disease. SWBAT explain how infectious diseases are spread. DO DONOW NOW VOCABULARY ACTIVITY #1 Activity #2 Exit DO NOW 1. How do diseases spread? 2. Name as many diseases as you can think of, star the ones that you would consider to be *infectious*. Vocabulary- Use your worksheet to define the words below. Germ theory of Disease Koch’s Postulates Zoonosis Infectious Disease Changes to body physiology that disrupt normal body functions and are caused by microorganisms. Examples: NonInfectious Disease Examples: ACTIVITY #1 Causes of Infectious Disease Changes to body physiology that disrupt normal body functions and are caused by microorganisms are called infectious diseases. Non-infectious diseases are not caused by pathogens and therefor cannot spread from one person to another. Microorganisms were commonly called “germs,” so this conclusion was called the germ theory of disease. Infectious diseases are caused by viruses, bacteria, fungi, protists, and parasitic worms. Disease-causing microorganisms are also called pathogens. Examples of infectious disease are common cold, influenza, ringworm, anthrax, malaria 1 Koch also developed a series of rules that help scientists identify which organism causes a specific disease. These rules are called Koch’s postulates. Many microorganisms are symbionts that are either harmless or beneficial. Pathogens cause disease by destroying cells, disrupting body functions, or releasing toxins that kill cells or interfere with their normal functions. How Diseases Spread I Infectious diseases can be thought of as organisms that cause adverse or unfavorable reactions in their host organisms. The host is the organism in which they live, such as an animal or plant. These organisms get into new host organisms by some kind of host-to- host contact. These diseases can be a type of fungus, virus, bacteria, protist, or macroparasitic (like insects). When an uninfected individual comes into contact with the infectious agent, the individual is said to be exposed to the disease. If, as a result of that exposure, the disease infects a susceptible individual (an individual capable of becoming infected with the disease), then we say the disease has been transmitted. Infectious diseases can be spread in several ways. Some infectious diseases are spread from person to person through coughing, sneezing, physical contact, or exchange of body fluids. Most infectious diseases are spread through indirect contact, such as pathogens that are carried through the air. These pathogens can be inhaled, or they can be picked up from surfaces. Some pathogens are spread by specific kinds of direct contact, such as sexual contact or drug use that involves shared syringes. Other infectious diseases are spread through contaminated water or food. Some infectious diseases spread from animals to humans. Such a disease is called a zoonosis. Often, the spread of zoonoses involves vectors, which are disease carriers that usually do not get sick from the pathogen. This invasion of a new individual – by one of these modes of transmission - resulting in the disease having a new host relies on a susceptible individual being exposed to the disease. THINK, PAIR, SHARE Explain how diseases are spread. __________________________________________________________________________________________________ __________________________________________________________________________________________________ __________________________________________________________________________________________________ __________________________________________________________________________________________________ Question: Answer in complete sentences. 1. What are infectious diseases, and what causes them? (Use this sentence starter! Infectious diseases are…) __________________________________________________________________________________________________ __________________________________________________________________________________________________ __________________________________________________________________________________________________ 2. How did the germ theory of disease get its name? __________________________________________________________________________________________________ __________________________________________________________________________________________________ __________________________________________________________________________________________________ 3. What is another name that scientists use for a disease-causing agent? ______________________________________________________________________________ ______________________________________________________________________________ __________________________________________________________________________________________________ 4. What are Koch’s postulates used for? __________________________________________________________________________________________________ __________________________________________________________________________________________________ __________________________________________________________________________________________________ 6. List two ways that bacteria can produce illness. __________________________________________________________________________________________________ __________________________________________________________________________________________________ 2 ACTIVITY #2 Not only do infectious diseases have different causes and different modes of transmission, they also have different effects in the body of the host. Diseases can cause symptoms in the host, and this is called being “symptomatic.” If the infected host does not show symptoms, it is called “asymptomatic.” The same disease can cause symptoms in some hosts but still not cause any symptoms in others. Frequently, people studying the disease will measure the rates of symptomatic disease rather than the overall rate of disease occurrence. This is because it is difficult to diagnose diseases that cause no symptoms. The easiest of these effects (and frequently the easiest to measure) is mortality risk — how likely the disease is to kill the host. In some cases treatments, such as taking an antibiotic, can affect mortality risks associated with particular diseases. This unit does not discuss the effects of treatment, but it can be interesting to consider the implications. Disease Categories Food and Water borne - pathogen is in a food or water source Blood Borne - carried in blood or other bodily fluids Sexually Transmitted - transmitted by sexual contact Zoonotic - carried by animals Airborne - carried by the air, often affect respiratory tract Common-Source - disease that infect populations from a contaminated source, such as water Host-to-Host - diseases that are transferred directly from infected people (or animals) Organizations Dealing with Health - Centers for Disease Control (CDC), World Health Organization (WHO), US Department of Health and Human Services (HHS), U.S. Army Medical Research Institute of Infectious Diseases Steps in Pathogenesis To cause disease, a pathogen must: Contact the host - be transmissible Colonize the host - adhere to and grow or multiply on host surfaces Infect the host - proliferate in host cells or tissues Evade the host defense system - by avoiding contact that will damage it Damage host tissues - by physical (mechanical) or chemical means 1. How can a pathogen cause disease? __________________________________________________________________________________________________ __________________________________________________________________________________________________ __________________________________________________________________________________________________ __________________________________________________________________________________________________ 2. Explain the difference between asymptomatic and symptomatic. __________________________________________________________________________________________________ __________________________________________________________________________________________________ __________________________________________________________________________________________________ 3. Explain three disease categories in detail. __________________________________________________________________________________________________ __________________________________________________________________________________________________ __________________________________________________________________________________________________ __________________________________________________________________________________________________ __________________________________________________________________________________________________ 3 Directions: Place the diseases below in the correct column. Common Cold Allergies Ear Infection Ulcer Appendicitis Migraines Flu Cancer Chicken Pox Arthritis Infectious or Communicable Diseases Heart Disease Lung Cancer Diabetes Athlete’s Foot Non-Infectious or Non-Communicable Diseases REGENTS QUESTIONS EXIT TICKET After the lesson, now I understand… Something I still need help with… 4 5 EXIT TICKET After the lesson, now I understand… ___________________________________________________________________________________________ ___________________________________________________________________________________________ Something I still need help with… ___________________________________________________________________________________________ 6 7
