Infectious Diseases Presented by: M. Alvarez Adapted from:M. Arias, C. Goedhart, and M.Burke.
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Transcript of Infectious Diseases Presented by: M. Alvarez Adapted from:M. Arias, C. Goedhart, and M.Burke.
Infectious DiseasesInfectious Diseases
Presented by: M. AlvarezAdapted from:M. Arias, C. Goedhart, and M.Burke
What is an Infection?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 diseaseBACTERIA
Tuberculosis, pneumonia, salmonella, anthrax FUNGUS
Athlete’s foot, ring wormPROTISTS
Malaria, toxoplasmosis, Algae
A harmful invasion and spread of foreign species, or pathogen, in a host. VIRUS
Small pox, measles, influenza, Ebola PRIONS
Cow’s diseaseBACTERIA
Tuberculosis, pneumonia, salmonella, anthrax FUNGUS
Athlete’s foot, ring wormPROTISTS
Malaria, toxoplasmosis, Algae
Estimated number of people in the world living with
HIV/AIDS in 2008
Estimated number of people in the world living with
HIV/AIDS in 2008
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
P
S
S
T
Susceptible
Immune
Sub-clinical
Clinical
ST
Spread of Disease & Transmission
Infection in one person can be transmitted to others
Routes of transmissionRoutes 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
Agent
Host
Environment
• Age
• Sex
• Genetics
• Behaviour
• Nutritional status
• Health status
• Infectivity
• Pathogenicity
• Virulence
• Antigenic stability
• Survival
• Weather
• Housing
• Geography
• Occupational setting
• Air quality
• Food
Factors Influencing Disease Transmission
What is Epidemiology?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.
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
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
Endemic Epidemic
Nu
mb
er o
f C
ases
of
a D
isea
se
Time
Disease Patterns
Outbreak InvestigationOutbreak Investigation
Basic steps in an outbreak investigation:Basic steps in an outbreak investigation:
1)1) Gather information and confirm Gather information and confirm existence of outbreakexistence of outbreak
2)2) Confirm diagnosisConfirm diagnosis
3) Establish a case definition – a 3) Establish a case definition – a standard set of criteria for standard set of criteria for identifying who has the diseaseidentifying who has the disease
4) Perform descriptive studies4) Perform descriptive studies
5) Develop and test hypotheses5) Develop and test hypotheses
6) Implement control and prevention6) Implement control and prevention
7) Report findings7) Report findings
The Spread of Infectious Diseasean epidemiological simulation
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?_______
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?_______
ProcedureProcedure1. 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.
2. 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.
3. 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.
1. 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.
2. 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.
3. 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.
Data Cup AData Cup AData Cup AData Cup AYour vial # _______ Your Your vial # _______ Your results______results______
Your vial # _______ Your Your vial # _______ Your results______results______
NameName Vial #Vial # DinnerDinner ResultResultss
11stst partnepartnerr
22ndnd partnepartnerr
Data Cup BData Cup BData Cup BData Cup BYour vial # _______ Your Your vial # _______ Your results______results______
Your vial # _______ Your Your vial # _______ Your results______results______
NameName Vial #Vial # DinnerDinner ResultResultss
11stst partnepartnerr
22ndnd partnepartnerr
Same from cup A
33rdrd partnepartnerr
44thth partnepartnerr
Same from cup A
Analysis QuestionsAnalysis Questions
1. Who was patient zero?______________________
2. How many students in the class were infected after two rounds of interactions?_____
3. How many students in the class were infected after four rounds of interactions?_____
4. Was your hypothesis correct?_________________
5. How many people do you think would be infected if you had ten interactions? Explain.
6. What kind of mathematical model best explains your data (i.e. is the pattern random, linear, etc.)?
7. List three infectious diseases you have heard of and how they are transmitted.
8. What are some ways you can prevent the spread of an infectious disease?