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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
What is epidemic?
A disease acquired in short time in one place
What is Pandemics?
An epidemic that is spreading through human populations across a large region
What is a reservoir?
A primary host population that harbors or maintains the pathogens, but shows no ill effect
What is a carrier?
Someone who has the disease and is affected by it
What is a vector?
- Disease causing organisms
- Ex: arthropods, ticks, etc.
What is a fomite?
- Non-living object that can spread infection
- Ex: tissues, drinking cups, syringes, needles,etc.
What are the three reservoirs?
Human, animal, and non-living object
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
What is a symptomatic?
A human reservoir that show signs and symptoms of the disease
What is an asymptomatic carrier?
A carrier that do not show signs or symptoms of the disease
What is zoonoses?
diseases that occur primarily in wild or domestic animals and can be transmitted to human in many ways
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
What are the contaminated source of water?
- Contaminated by human/animal feces
- Contain pathogen
What is the name of person to person transmission?
What is direct transmission?
person to person or person to animal transmission
What is an Index Case?
First case of a disease
What is indirect contact?
Contact to a fomite or droplet transmission
What is the difference between droplet transmission and air transmission?
Droplet are produced by the reservoir that is about 1 meter away from host.
How does waterborne transmission occur?
- Water contaminated with untreated or poorly treated sewage.
- Ex: cholera
How does foodborne transmission occur?
- Food incompletely cooked, poorly refrigerated or unsanitarily prepped
- Ex: food poisoning, tapeworm
How do airborne transmission occur?
- Droplets from coughing or sneezing that travel more than 1 meter.
- Ex: Tuberculosis and measles
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
What is the incidence rate?
It conveys information about the risk of contracting the disease
How to calculate incidence rate?
number of new cases of a disease reported in a defined population during a specific period of time.
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
How do you calculate point prevalence?
Number of cases of a disease at a specific point in time in a defined population
What is ELISA?
Enzyme-linked immunosorbent Assay
What is an antigen?
- any foreign substance that cause antibody formation
- Elicit an immune resposne
What is an antibody?
- Proteins made in response to counteract an antigen
- Y shape, made from dna
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
What can immunoassays dectect?
Antigen( Ag) or antibodies (Ab)
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
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)
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.
What are some uses for Direct ELISA?
- Detect drugs in urine
- Home pregnancy test that detect hCG(human chorionic gonadotropin)
What is the use of Indirect ELISa?
Detection of HIV
What is the purpose of the indirect Elisa test in lab?
To detect Legiionellosis
What is Legionellosis?
- It is an acute respiratory infection caused by Legionella pneumophila.
- Has pneumonia symptom
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
How do you treat Legionaire's disease?
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
What is secondary response or Memory response?
- Peak at 2-7 days
- Last longer and is greater in magnitude
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
Titer greater than 128 mean?
Evidence of recent infection with Legionella
Titer greater than 256 mean?
provides presumptive evidence of infection at an undetermined time
Single titers of less than 256 mean?
not considered an infection
Why do we add horseradish peroxidase?
to link IgG antibodies
Why do we add enzyme specific substrate?
To produce the blue color for detection