The Epidemiologic Triangle Switch gears: really bring in society this time with epidemiology Contagion Trailer: http://www.rottentomatoes.com/m/contagion_2011/trailers/ After: What did they say about how often we touch our face? Why do you think this might be important? Why do they show images of cars, bridges, planes, etc.? Contagion

Epidemiology: What is it? Epi – means “on, upon, befall” (ex: epidermis) Demo – means “people” (ex: demographics, the study of populations) -ology – means “the study of”(ex: biology, geology) So, epidemiology literally translates to “the study of that which befalls people” Epidemiology – learning how diseases are distributed in a certain place and time

John Snow: The First Epidemiologist Read “Finding the Real Cause of Cholera” with your table. What did John Snow think was causing the cholera outbreak? How do you think John Snow proved his theory using the scientific method?

John Snow: The First Epidemiologist Read “John Snow’s Methods” How did John Snow prove that cholera was being spread by contaminated water?

Epidemiology The Center for Disease Control (CDC) uses a model called the Epidemiologic Triangle to pinpoint outbreaks of infectious diseases The triangle has three vertices: Agent, or microbe that causes the disease (the “What” of the triangle Host, or organism harboring the disease (the “who” of the triangle) Environment, or those external factors that cause or allow disease transmission (the “where”) HOST The center of the triangle is TIME – this is what epidemiologists are working against TIME Agent: The agent is the cause of the disease. When studying the epidemiology of most infectious diseases, the agent is a microbe—an organism too small to be seen with the naked eye. Disease-causing microbes are bacteria, virus, fungi, and protozoa (a type of parasite). They are what most people call “germs.” Bacteria, fungi, viruses, parasites Host: Hosts are organisms, usually humans or animals, which are exposed to and harbor a disease. The host can be the organism that gets sick, as well as any animal carrier (including insects and worms) that may or may not get sick. Although the host may or may not know it has the disease or have any outward signs of illness, the disease does take lodging from the host. The “host” heading also includes symptoms of the disease. Different people may have different reactions to the same agent. For example, adults infected with the virus varicella (chickenpox) are more likely than children to develop serious complications. Environment: The environment is the favorable surroundings and conditions external to the host that cause or allow the disease to be transmitted. Some diseases live best in dirty water. Others survive in human blood. Still others, like E. coli, thrive in warm temperatures but are killed by high heat. Other environment factors include the season of the year (in the U.S., the peak of the flu season is between November and March, for example). AGENT ENVIRONMENT

Outbreaks, Epidemic vs. Endemic An outbreak or epidemic exists when there are more cases of a particular disease than expected in a given area, or among a specific group of people, over a particular time. Example: Seasonal flu Endemic means a population has a high level of disease all the time. Example: Malaria is endemic in Africa How does an epidemic reinforce OR challenge the American ideal that “all men are created equal”?

Example Case Study: Varicella zoster (chickenpox) People under 15 most at risk Anyone who hasn’t had it is susceptible Can remain in the body and cause shingles (painful blisters) in adults HOST Transmitted from an infected person through coughs or sneezes, or from contact with the fluid from chickenpox blisters Most commonly transmitted in the early winter or spring, when temperatures are moderate Varicella zoster, a virus AGENT ENVIRONMENT

Mystery Disease Watch the following clip: Mystery Disease While watching, look for the following epidemiological clues: How might it be spreading? (Agent) Who/what is getting disease? (Host) Where is it happening? (Environment) Share out student observations as a class

Mystery Solved! Let’s see if you were right… Mystery Solved Review agent, host, environment with class

Public Service Announcement Skits Working in your table groups, use the information from the case study provided to create a Public Service Announcement skit about your disease. It can be a radio broadcast, TV commercial, talk show interview, etc… be creative! In your skit, include… The epidemiological triangle for how your disease is transmitted, including time -What people should do avoid getting disease TIME HOST ENVIRONMENT AGENT Resources: CDC, NIH Use Cardstock info Extensions/Alternative Activities: A news story, Eggs with agent/host/environment that students must identify each component; a radio broadcast;

Common Infectious Diseases (HW or Classroom Activity) I’ve Had Family Members Have Had Heard About Compare the diseases you’ve had, and diseases your family has had with your table. What diseases do you have in common? What diseases did your family have that you haven’t had? Why do you think this is? What are some diseases you’ve heard about, but don’t know anyone who has had that disease? Do activity with teachers