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Infectious Diseases

Infectious Diseases. Presented by: M. Alvarez Adapted from:M. Arias, C. Goedhart, and M.Burke. What is an Infection?. A harmful invasion and spread of foreign species, or pathogen, in a host. VIRUS Small pox, measles, influenza, Ebola PRIONS Cow’s disease BACTERIA

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Infectious Diseases

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  1. Infectious Diseases Presented by: M. Alvarez Adapted from:M. Arias, C. Goedhart, and M.Burke

  2. What is an Infection? A harmful invasion and spread of foreign species, or pathogen, in a host. • VIRUS • Small pox, measles, influenza, Ebola • PRIONS • Cow’s disease • BACTERIA • Tuberculosis, pneumonia, salmonella, anthrax • FUNGUS • Athlete’s foot, ring worm • PROTISTS • Malaria, toxoplasmosis, Algae

  3. Infectious Agents

  4. Worldwide mortality due to infectious diseases

  5. Estimated number of people in the world living with HIV/AIDS in 2008

  6. T S P Susceptible S Immune S T Sub-clinical Clinical Spread of Disease & Transmission • Infection in one person can be transmitted to others • Cases • Patient “Zero” – the first case identified • Primary – the case that brings the infection into a population • Secondary – infected by a primary case • Tertiary – infected by a secondary case

  7. Transmission of Pathogens • Direct contact • Indirect contacts • Air • Objects • Vectors

  8. Routes of transmission • Direct • Skin-skin • Herpes type 1 • Mucous-mucous • STI • Across placenta • toxoplasmosis • Through breast milk • HIV • Sneeze-cough • Influenza • Indirect • Food-borne • Salmonella • Water-borne • Hepatitis A • Air-borne • Chickenpox • Vector • A carrier of an infectious agent • Ex. Malaria Parasite carried by Mosquito

  9. Factors Influencing Disease Transmission Agent Environment • Weather • Housing • Geography • Occupational setting • Air quality • Food • Infectivity • Pathogenicity • Virulence • Antigenic stability • Survival • Age • Sex • Genetics • Behaviour • Nutritional status • Health status Host

  10. What is Epidemiology? • Epidemiology is the science of discovering causes of illness and injury in populations. • Epidemiology studies are used to control and prevent health problems.

  11. Number of Cases of a Disease Epidemic Endemic Time Disease Patterns • Endemic • Transmission occur, but the number of cases remains constant • Epidemic • The number of cases increases • Pandemic • When epidemics occur at several continents – global epidemic

  12. Outbreak Investigation • Basic steps in an outbreak investigation: • Gather information and confirm existence of outbreak • Confirm diagnosis • 3) Establish a case definition – a standard set of criteria for identifying who has the disease • 4) Perform descriptive studies • 5) Develop and test hypotheses • 6) Implement control and prevention • 7) Report findings

  13. The Spread of Infectious Diseasean epidemiological simulation • Objective: This activity will simulate the spread of an infectious disease. Our simulation will show how an infectious disease can spread from one infected person to other people, who in turn infect others. • Hypotheses • 1. How many people will be infected after two rounds of interactions? _______ • 2. How many people will be infected after three rounds of interactions?_______

  14. Procedure • Obtain a cup labeled A filled with a clear solution (body fluid). Only one person in the class will have a cup that has been “infected”. Do not drink from the cup. • In this part of the activity, you will interact with two other students. To interact with another student, pour all of your solution into your partner’s cup, then have your partner pour half of the mixed solution into your cup. Then move to another part of the classroom and interact with a second student. • Repeat step 2 with cup B, this time interacting with four students. 4. Your teacher or I will come around and put an “infection indicator” in your cups. If you have exchanged solutions an infected person, you are now infected and your solution will turn pink.

  15. Data Cup A Your vial # _______ Your results______

  16. Data Cup B Your vial # _______ Your results______ Same from cup A

  17. Analysis Questions Who was patient zero?______________________ How many students in the class were infected after two rounds of interactions?_____ How many students in the class were infected after four rounds of interactions?_____ Was your hypothesis correct?_________________ How many people do you think would be infected if you had ten interactions? Explain. What kind of mathematical model best explains your data (i.e. is the pattern random, linear, etc.)? List three infectious diseases you have heard of and how they are transmitted. What are some ways you can prevent the spread of an infectious disease?

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