Science Olympiad Disease Detectives

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Terms in this set (...)

Vector
A tsetse fly is a ________________ for trypanosoma.
Cluster
An aggregation of cases over a particular
period of time.
Morbidity
The rate of incidence of a disease.
Bias
Surveillance is an example of this.
Agent
Lactobacillus is an example of this.
Incubation period
The time that lapses between infection and
the first appearances of the symptoms of
the disease.
Mortality
The measure of the frequency of death.
Virulence
Severity of disease in a host.
Epidemiology
The study of patterns, causes, effects, and
disease conditions in a population.
Infectivity
The capacity to cause infection in a host.
Parasite
An organism that depends on another
organism.
Risk
The probability that one will become infected by an illness or injury within a specific period of time.
Pathogenicity
Capacity of a host to cause disease.
Surveillance
The systematic collection, analysis, and
interpretation of data.
Pandemic
Occurrence of a phenomenon over several
countries and geographic locale with a
large population affected.
Prevalence
Proportion of the host population infected
at a given time.
Pathogenicity
Capacity to cause disease in a host.
Incidence
The rate at which new cases of infection
arise in a population.
Outbreak
More cases of a particular disease than
expected in a given area, at a given time.
Zoonosis
Rabies in an example of this.
Fomite
A hairbrush carrying lice would be an
example of this.
Reservoir
Soil is an example of this.
1. Prepare for field work, 2. Establish the existence of an outbreak, 3. Verify the diagnosis, 4. Define and identify the cases, 5. Describe in terms of time, place and person, 6. Develop a hypothesis, 7. Evaluate the hypothesis, 8. Refine hypothesis, 9. Implement control and prevention measures, 10. Communicate findings
Name the ten steps to an outbreak investigation.
Environment, Host, Agent or Time, Person, Place
What are the three components of the
epidemiological triad?
Biological - bacteria, viruses
Nutritional - lack of nutrition, excess nutrition (obesity)
Chemical - poison, alcohol
Physical - radiation, trauma
Provide two examples of the following
agents: (ANSWERS MAY VARY)
Biological -
Nutritional -
Chemical -
Physical -
Epicurve
What do epidemiologists call a graph like the one below?
1. Point
2. Common continuous
3. Propagated
Name the three types of this graph that one can potentially visualize. Write them next to
the graphs below.
1. Strength of association, 2. Consistency, 3. Specificity, 4. Alternative explanations, 4. Temporality, 5. Dose-response relationship, 6. Biological plausibility, 7. Experimental evidence, 8. Coherence
List all of Hill's Criteria of Causation.
agent, reservoir, portal of exit, mode of transmission, portal of entry, susceptible host.
Present a the Chain of Infection.
•Influenza: VIRAL
•Aspergillus: FUNGAL
•Gonorrhea: BACTERIAL
•Ascaris: PARASITIC
•Tuberculosis: BACTERIAL
•Toxic Shock Syndrome: BACTERIAL
•Genital Warts: VIRAL
•Strongyloides: PARASITIC
•Chagas disease: PARASITIC
•Cholera: BACTERIAL
Understanding the biological underpinnings of diseases is important. Determine
whether the following diseases are bacterial, viral, fungal, or parasitic in origin. Write the
origin next to each disease.
•Influenza:
•Aspergillus:
•Gonorrhea:
•Ascaris:
•Tuberculosis:
•Toxic Shock Syndrome:
•Genital Warts:
•Strongyloides:
•Chagas disease:
•Cholera:
In 2009, a community survey of people who went on the Zipper at the Syosset Carnival for blood pressure was conducted in which residents were asked how many times they had their blood pressure tested in the past year. The answers from the first 20 participants
are listed below. In 2014, they did the same thing.

2009: 0, 2, 0, 0, 24, 1, 2, 0, 2, 2, 1, 1, 0, 0, 5, 1, 360, 10, 2, 3
2014: 2, 1, 0, 0, 2, 1, 4, 3, 2, 1, 0, 4, 2, 52, 1, 9, 2, 7, 4, 5

Organize the data into a table of frequency distribution. Find the mean, median, and mode of the data set. You must set the columns for the distribution yourself.
a.) Systematic deviation of results or inferences
b.) Surveillance, Selection
c.) Widen the study base by contacting people at other
locations, including (but not limited to) hospitals,
preschools, elementary schools, and middle schools,
various businesses and workplaces, and senior homes.
An epidemiologist decides to investigate the effects of a severe heat wave that occurred at Chicago from July 10, 2011 to July 20, 2011, during which temperatures
often exceeded 40°C. To do this, he visits 10 public and private high schools located in Chicago and 20 others scattered around the state of Illinois. Each student fills out a survey asking them about their living conditions and experiences during those 10 days, any preexisting health conditions, and any changes in health during or following the heat wave.
a.) Define bias
b.) What is one type of bias identified in this study?
c.) How can this study be altered to change its bias?
Selection bias: occurs when study subjects are selected for the study as a result of a third unmeasured variable which is association with both the exposure and the
outcome.
Explain what study the epidemiologists are utilizing:
1. Epidemiologists identify a population that is exposed to a suspected carcinogen and a non-exposed population and track them to determine who develops leukemia.
Recall bias: In a case control study, patients do not remember exposures that they do not believe caused the disease as well as those they believe did cause it (cases) and they don't recall some exposures as clearly as cases (controls)
Explain what study the epidemiologists are utilizing: Switzerland is determine to have a higher breast cancer incidence and a higher consumption of dietary fat when compared with other countries.
Information bias: Occurs from systematic error in the assessment of a variable
Explain what study the epidemiologists are utilizing: Epidemiologists are interested in the possible relationship involving increased serum cholesterol level (exposure) to electrocardiographic (ECG) evidence of CHD (the disease). They survey a population; for each participant they determine the serum cholesterol level and perform an ECG subsequently for evidence of CHD.
True
Infectious disease are more likely to be distributed to others in a larger population: (2 pts.)
True or False
d. The exposed and non-exposed groups under study be as similar as possible with regard to possible confounding factors
In cohort studies of the role of a suspected factor in the etiology of a disease, it is essential that:
a. There be an equal number of persons in both study groups
b. At the beginning of the study, those with the disease and those without the disease have equal risks of having the factor
c. The study group with the factor and the study group without the factor be representative of the general population
d. The exposed and non-exposed groups under study be as similar as possible with regard to possible confounding factors
e. Both b and c
a. It usually costs less than a case control
Which of the following is not an advantage of having a prospective cohort study
a. It usually costs less than a case control
b. Precise measurements of exposure is possible
c. Incidence rates can be calculated
d. Recall bias is minimized compared to a case control study
e. Many disease outcomes can be studied simultaneously
a. The possibility that a factor that led to the exposure, rather than the exposure itself might have caused the disease
A major problem resulting from the lack of randomization in a cohort study is:
a. The possibility that a factor that led to the exposure, rather than the exposure itself might have caused the disease
b. The possibility that a greater proportion of the people in the study may have been exposed
c. The possibility that a smaller proportion of people in the study may have been exposed
d. That, without randomization, the study may take longer to carry out
e. Planned crossover is more likely
c. Incidence rates may be computed directly
A case control study is characterized by all of the following except:
a. It is relatively inexpensive compared with most other epidemiologic study designs
b. Patients with the disease (cases) are compared with persons without the disease (controls)
c. Incidence rates may be computed directly
d. Assessment of past exposure may be biased
e. Definition of cases may be difficult
e. a, c, and d
In a case-control study, which of the following is true?
a. The proportion of cases with the exposure is compared with the proportion of controls with the exposure
b. Disease rates are compared for people with the factor of interest and for the people without the factor of interest
c. The investigator may choose to have multiple comparison groups d. Recall bias is a potential problem
e. a, c, and d
d. Case-crossover study
In which of the following types of study designs does a subject serve as his own control
a. Prospective cohort study
b. Retrospective cohort study
c. Case-control study
d. Case-crossover study
e. Case-cohort study
c. Ascribing the characteristics of a group to every individual in that group
Ecological fallacy refers to:
a. Assessing exposure in large groups rather than in many groups
b. Assessing outcome in large groups rather than in small groups
c. Ascribing the characteristics of a group to every individual in that group
d. Examining correlations of exposure and outcomes rather than time periods
e. Failure to examine temporal relationships between exposures and outcomes
1. Use an approved insect repellent every time you go outside. Approved repellents are those that contain DEET, picaridin or oil of lemon eucalyptus. Follow the
instructions on the label.
2. Regularly drain standing water, including water that collects in empty cans, tires, buckets, clogged rain gutters and saucers under potted plants. Mosquitoes breed in stagnant water.
3. Wear long sleeves and pants at dawn and dusk when mosquitoes are most active.
4. Use air conditioning (instead of open windows) or make sure there are screens on all doors and windows to keep mosquitoes from entering the home.
5. anything else that is reasonable that would indeed reduce the exposure of skin to mosquitos or reduce the amount of mosquitos that could carry West Nile. Grader give leniency equally to all teams.
What are some preventive measures you can take to lessen the chance of being infected with West Nile Virus: worth 3 points, 1pt per correct response. can give up to four answers for 4 pts.
The term "outbreak" simply refers to the presence of more cases than expected of a certain disease in a group of people. An epidemic is a larger outbreak, it is spread across a wide geographical area and larger numbers of people are affected. A pandemic is a larger epidemic in which people across the entire world can be affected. If you were to rank them by "size" from smallest to largest, it would be: outbreak, epidemic,
pandemic.
What is the difference between an outbreak, an epidemic and a pandemic?
Vectors differ from vehicles and fomites because they are living (Vector = Living; Fomite and Vehicle: Non-living).
A fomite serves to transmit an infectious agent from person to person, while a vehicle is an object (food, water, blood, etc) that may indirectly transmit an infectious agent from a reservoir to a host
All fomites are vehicles, but not all vehicles are fomites.
What is the difference between a vector, fomite and vehicle?
Symptoms are felt by patient, they are subjective. Example of a symptom- headache, nausea, excessive hunger or thirst
Signs are observable by others. Example of a sign- welts on skin, discoloration of skin, rashes, runny nose
What is the difference between a symptom and a sign?
If people who are well, but suspected to have been exposed, are separated, it is referred to as quarantine
If people who are confirmed to be infected are separated, it is referred to as isolation
What is the difference between quarantine and isolation?
Relative risk is a calculation used to estimate the extent of the association between an exposure and a
disease. It estimates the likelihood of developing the disease in the exposed group compared to the
unexposed group.
What is the purpose of calculating relative risk, in general?
A positive association or an increased risk; This risk increases in strength as the magnitude of the
relative risk increases.


A RR of less than one indicates that the incidence rates of disease in the exposed group is equal to the
incidence rate in unexposed group. Therefore the data does not provide evidence for an association.
What does a relative risk of greater than one indicate?

What does a relative risk equal to one indicate?
Prevalence- for one point in time, take the number of people with the disease and divide it by the total population. Then, multiply by 1,000; 10,000; or 100,000 (whichever is most fitting for the population size that you're dealing with)

Incidence- number of new cases over period of time divided by size of population at risk during period of time, multiplied by 1,000; 10,000; or 100,000 (depending on population size).

Incidence is the measure of a number of NEW cases of a disease, while prevalence is for one
point in time.
How is prevalence calculated? Incidence?

15. What is the difference between prevalence and incidence?
Analytical studies tell why people have the disease and how it spreads; Descriptive studies tell who has
the disease, what the disease is, when the disease was discovered/first identified (etc) , and where the
outbreak of the disease is occurring
What type of data is generally provided by analytic studies? Descriptive studies?
A retrospective study looks backwards and examines exposures to suspected risk or protection factors in relation to an outcome that is established at the start of the study.
A prospective study watches for outcomes, such as the development of a disease, during the study period and relates this to other factors such as suspected risk or protection factor(s).
What is the difference between a retrospective study and a prospective study?
Pros
Good Measure of Exposure;
You can tell causality:
Able to study multiple diseases at once
Cons
Time Consuming;
Expensive;
Not good for diseases that are rare or take a
long time to develop;
Loss of follow-up;
Pros and Cons of Study Designs - Cohort
Pros
Fast and Cheap;
Use information that is readily available
Cons
Cannot control for effects of confounding
factors;
No information on level of exposure;
Ecological Fallacy
Pros and Cons of Study Designs - Ecological
Pros
Fastest;
Least Expensive;
Useful for generating hypotheses;
Useful for public health planning;
Data on all variables is only collected once;
Able to measure prevalence for all factors under investigation;
Multiple outcomes and exposures can be studied;
Cons
Possible Time-Order Confusion;
Least Confidence in Findings;
Provides no info about causality;
Prevalence- incidence Bias;
Unable to measure incidence;
Difficult to determine whether the outcome followed exposure in Time or exposure resulted from the outcome;
Not suitable for studying rare diseases or diseases with a short duration.
Pros and Cons of Study Designs - Cross-Sectional
Pros
Can Study Rare diseases;
Relatively Less Expensive;
Relatively Fast;
Lots of different exposures;
Don't need huge sample size;
Cons
Possible Time-Order Confusion
Possible Error in Recalling Past Exposures
(Recall bias);
Only can deal with one disease at Time;
Hard to tell causality
Pros and Cons of Study Designs - Case-Control
A set of uniformly applied criteria for determining whether a person should be identified as having a particular disease, injury, or other health condition. In epidemiology, particularly for an outbreak investigation, a case definition specifies clinical criteria and details of Time, place, and person.
What is a case definition?
Cover mouth when coughing and sneezing; Wash hands; Use Kleenex; Disinfect commonly touched surfaces frequently
Disease Prevention & Modes of Transmission - Droplet Spread
Use bug spray; Stay away from areas heavily populated by mosquitoes; Cover as much skin as possible with clothes; Frequently take breaks indoors
Disease Prevention & Modes of Transmission - Mosquito-Borne
Cook all food thoroughly; Wash surfaces used to prepare food; Wash hands regularly; Keep your fridge and freezer at the correct temperature;
Disease Prevention & Modes of Transmission - Food-Borne
Clean surfaces touched by small children frequently; Make sure children are wearing fresh diapers; Disinfect bathroom surfaces regularly;
Disease Prevention & Modes of Transmission - Fecal-Oral
a. Anthrax = Direct contact, Contact with a contaminated surface
b. Brucellosis = contact with infected tissues, blood, urine, vaginal discharges
c. Mumps = Droplet
d. Ebola = Direct contact, through droplets
e. Smallpox = Droplet
f. Measles = Droplet or direct contact
g. Chicken Pox = Droplet (coughing or sneezing)
Indicate the mode of transmission for each disease:
a. Anthrax =
b. Brucellosis =
c. Mumps =
d. Ebola =
e. Smallpox =
f. Measles =
g. Chicken Pox =
Null Hypothesis- a general statement or default position that there is no relationship between two measured phenomena
Define a Null hypothesis.
Epidemiology
study of distribution & determinants of health states in specified populations & this app. of this study to control health problems.
Etiology
study of causation of a disease; the cause, set of causes, or manner of causation of a disease or condition
Epidemiological Triad
traditional model of disease causation. External agent, a susceptible host, an environment that brings the two together
Chain of Transmission Triad
external agent, a vector or fomite that transmits disease, a susceptible host; defines major points of a disease case
Cluster
an aggregation of cases over a particular period closely grouped in time and space. Doesn't matter the number of cases.
Surveillance
the systematic collection, analysis, interpretation, and dissemination of health data. Used to prevent or control.
Risk
the probability that person will be affected by, or die from, an illness or injury within a stated time or age span
Incubation Period
time between person comes into contact with pathogen and when symptoms are first shown.
Virus
a disease-causing particle with no nucleus, a protein coat, and RNA or DNA core
Morbidity
the proportion of sickness or of a specific disease in a geographical locality
Mortality
the relative frequency of deaths in a specific population; death rate (Natality is birth rate)
Virulence
the relative ability of a microorganism to cause disease; degree of pathogenicity; the capability of a microorganism to cause disease
Case Definition
should include person, place, time, and clinical information, sequence of disease development
Contact Transmission
(direct contact- person-to-person, indirect- fomite, droplet- cough sneeze spit) Direct occurs through touching, kissing, sexual intercourse. To prevent, use gloves, masks, condoms. Indirect contact occurs through inanimate objects (fomites: a physical object that serves to transmit an agent). Exceptions are food, air, and liquids. Droplet contact occurs by mucous droplets travelling up to one meter out of the mouth.
Vehicle Transmission
transmitted via a medium, which is taken into the body. (airbourne- via droplets that remain airborne, foodborne- via pathogens in improperly handled food, water-borne- fecal contaminated water) Airbourne occurs through suspended droplets or organisms that find their way into the air. Foodborne occurs through pathogens not killed during processes and can be transmitted when eaten. Water-borne occurs by sewage-contaminated water.
Vector Transmission
pathogens transmitted through animals to person.
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