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What is epidemiology?
Science that deals with when diseases occur, where it occurs, and how they are transmitted, caused and prevention
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What is epidemic?
A disease acquired in short time in one place
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What is Pandemics?
An epidemic that is spreading through human populations across a large region
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What is a reservoir?
A primary host population that harbors or maintains the pathogens, but shows no ill effect
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What is a carrier?
Someone who has the disease and is affected by it
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What is a vector?
- Disease causing organisms
- Ex: arthropods, ticks, etc.
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What is a fomite?
- Non-living object that can spread infection
- Ex: tissues, drinking cups, syringes, needles,etc.
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What are the three reservoirs?
Human, animal, and non-living object
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What are the three type of transmission?
- Contact transmission: Direct or indirect (droplets) contact.
- Vehicle Transmission: By water, food or air.
- Vector Transmission: animals that carry pathogens from one host to another
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What is a symptomatic?
A human reservoir that show signs and symptoms of the disease
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What is an asymptomatic carrier?
A carrier that do not show signs or symptoms of the disease
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What is zoonoses?
diseases that occur primarily in wild or domestic animals and can be transmitted to human in many ways
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What are some common pathogen in soil? common cause of contamination in soil
- Clostridium botulinum that cause botulism.
- Clostridium tetanii that cause tetanus.
- Normal intestinal microbiota of farm animal
- Feces in fertilizer contaminate soil
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What are the contaminated source of water?
- Contaminated by human/animal feces
- Contain pathogen
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What is the name of person to person transmission?
Propagated transmission
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What is direct transmission?
person to person or person to animal transmission
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What is an Index Case?
First case of a disease
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What is indirect contact?
Contact to a fomite or droplet transmission
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What is the difference between droplet transmission and air transmission?
Droplet are produced by the reservoir that is about 1 meter away from host.
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How does waterborne transmission occur?
- Water contaminated with untreated or poorly treated sewage.
- Ex: cholera
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How does foodborne transmission occur?
- Food incompletely cooked, poorly refrigerated or unsanitarily prepped
- Ex: food poisoning, tapeworm
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How do airborne transmission occur?
- Droplets from coughing or sneezing that travel more than 1 meter.
- Ex: Tuberculosis and measles
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What are the two type of vector transmission?
- Mechanical transmission: passive transport of pathogen on insects body parts
- Biological transmission: arthropod bites an infected person and the pathogen reproduces in the vector via the feces or vomit or salivary of the arthropod
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What is the incidence rate?
It conveys information about the risk of contracting the disease
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How to calculate incidence rate?
number of new cases of a disease reported in a defined population during a specific period of time.
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What is the point prevalance?
tell you how widespread a disease is in a population but does not tell you about the risk of contracting the disease
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How do you calculate point prevalence?
Number of cases of a disease at a specific point in time in a defined population
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What is ELISA?
Enzyme-linked immunosorbent Assay
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What is an antigen?
- any foreign substance that cause antibody formation
- Elicit an immune resposne
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What is an antibody?
- Proteins made in response to counteract an antigen
- Y shape, made from dna
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What is a titer?
- A way of expressing concentration.
- Uses serial dilution to obtain approximate quantitative value
- Corresponds to the highest dilution factor that is positive
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What can immunoassays dectect?
Antigen( Ag) or antibodies (Ab)
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What are the steps in ELISA?
- 1. For indirect Elisa, first introduce known antigen. For a direct Elisa, first introduce known antibody.
- 2. Introduce the unknown(antigen or antibody) into the wells
- 3. Introduce a second antibody( bind against the human antibody) and produce a detectable change
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What is ELISA use for?
- Measure antibody levels(allergies, vaccines)
- Detect viruses (hepatitis, HIV, venereal disease)
- Detect hormonal changes (pregnancy) direct
- Detect circulatory inflammatory markers( cytokines)
- Detect antigen-indicator of infection(sufficient amount would show a positive test)
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What is the differences between direct and indirect Elisa?
- Direct Elisa use antibody to measure antigen and the second antibody bind to the antigen, not the antibody.
- Indirect Elisa use antigen to measure antibody and the second antibody bind to the human antibody.
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What are some uses for Direct ELISA?
- Detect drugs in urine
- Home pregnancy test that detect hCG(human chorionic gonadotropin)
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What is the use of Indirect ELISa?
Detection of HIV
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What is the purpose of the indirect Elisa test in lab?
To detect Legiionellosis
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What is Legionellosis?
- It is an acute respiratory infection caused by Legionella pneumophila.
- Has pneumonia symptom
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Where do we find Legionella pneumophila? What is it resistant to in water?
- Isolated from water sources such as himidifiers, showers, spas.
- It is resistance to chlorine
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How do you treat Legionaire's disease?
Erythromycin treatment
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What is the primary response to antigen?
- no detectable antibody for 4-7 days.
- Slow rise in antibody titer
- Peak at 10-17 days and decline after
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What is secondary response or Memory response?
- Peak at 2-7 days
- Last longer and is greater in magnitude
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List the concentration of antibody of a person if that person is
a) never been infected
b) carrier or active infection
c)Recovering from an infection
- A: person should not have any antibodies
- B: Has antibodies at any state or increasing Abs
- C: Decreasing antibodies
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Titer greater than 128 mean?
Evidence of recent infection with Legionella
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Titer greater than 256 mean?
provides presumptive evidence of infection at an undetermined time
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Single titers of less than 256 mean?
not considered an infection
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Why do we add horseradish peroxidase?
to link IgG antibodies
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Why do we add enzyme specific substrate?
To produce the blue color for detection
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