Epidemiology Review

First to use a geographical display of diseased cases.

John Snow

An advantage of using hospital-based controls is that they are more likely to cooperate and are likely to remember past exposures with the same accuracy as the cases. T/F?

True

Epidemiology, as defined in this lesson, would include which of the following activities? A. Describing the demographic characteristics of persons with acute aflatoxin poisoning in District A B. Prescribing an antibiotic to treat a patient with community-acquired methicillin-resistantStaphylococcus aureus infection C. Comparing the family history, amount of exercise, and eating habits of those with and without newly diagnosed diabetes D. Recommending that a restaurant be closed after implicating it as the source of a hepatitis A outbreak

A, C, D. Epidemiology includes assessment of the distribution (including describing demographic characteristics of an affected population), determinants (including a study of possible risk factors), and the application to control health problems (such as closing a restaurant). It does not generally include the actual treatment of individuals, which is the responsibility of health-care providers.

In the definition of epidemiology, "distribution" refers to descriptive epidemiology, while "determinants" refers to analytic epidemiology. So "distribution" covers time (when), place (where), and person (who), whereas "determinants" covers causes, risk factors, modes of transmission (____ and ____).

why; how

Disease prevalence is measured using the following formula: A. Number of new cases of a disease occuring in the population during a certain period of time/number of person at risk of developing teh disease during that time period B. Number of person who die from disease/number of persons infected with the disease C. Number of cases of a disease during a particular period of time/number of existing cases of a disease during a particular period of time D. Total number of cases ( exisiting &new) in the population during a specific period of time/number of person in the population at that specific time period

D

In the definition of epidemiology, the terms "distribution" and "determinants" taken together refer to: A. public health services and resources B. knowledge, attitudes, and practices related to health C. dissemination of disease risk factor related information D. frequency, pattern, and factors related to the occurrence of health events

D

The selection of controls (i.e. the comparison group) in a case-control study is guided by which of the following principles? (Select all that apply.) A. If cases are selected from the general population then controls should always be selected from hospital based settings B. It is more time consuming, costly and logistically challenging to identify and recruit friends and family members as controls compared to controls from the general population C. Choosing controls from different setting than those the cases came from will not cause a bias D. To avoid selection bias, controls should be selected from the same population that gave rise to the cases

D

Which of the following statements correctly describes case-control studies? A. Both cohort studies and case-control studies allow one to compare incidence measures B. An odds ratio can be calculated only in case-control studies and not in cohort studies C. It is correct to interpret an odds ratio as if it were a rate ratio D. The odds ratio calculated in a case-control study yields a fairly good approximation to the relative risk provided the outcome is uncommon

D

Considered to be the first true epidemiologist who explained disease on a rational basis.

Hippocrates

Who evaluated the Bills of Mortality to understand trends in causes of death in London.

John Graunt. Graunt is widely credited as one of the first demographers who used the Bills of Mortality in London to identify variations in death according to sex, residence, season and age.

Conducted a famous study of a large outbreak of cholera in London in 1854. He is credited with creating a spot map that shows the households that experienced a cholera death clustered around the Broad Street Pump.

John Snow

______ is used by public health professionals as a measure for estimating the burden of a health condition or health-related behaviors in a given population

Prevalence

Founder of modern epidemiology who applied vital statistics to epidemiologic problems.

William Farr

In the definition of epidemiology, "determinants" generally includes the causes (including agents), risk factors (including exposure to sources), and modes of transmission, but does not include the resulting public health ______.

action

Which of the following are requirements for herd immunity to be achieved? (Check all that apply). A. Prior infections must induce solid immunity B. Disease agent restricted to a single host species within which transmission occurs C. Outbreaks occur only in randomly mixing populations D. Prevention of highly contagious diseases requires a small proportion (< 5%) of the population to be immunized against the disease

A, B, C. Disease agent restricted to a single host species within which transmission occurs: CORRECT; the disease has to be restricted to a single host species. So, if you're dealing with a disease where animal species can also act as hosts, then you will not be able to achieve herd immunity in humans. Prior infections must induce solid immunity: CORRECT; if the disease has been previously experienced, then that prior infection must confer full immunity. If it's just a partial immunity, then you will not be able to achieve a community level immunity. Outbreaks occur only in randomly mixing populations: CORRECT; in order for Herd immunity to work, you must assume that people in your population are randomly mixing. If that's not the case, then the probability of encountering a person who is not immunized would be significantly higher.

Which of the following are advantages to case-control studies? (Select all that apply). A. They tend to be less expensive and more efficient than prospective cohort studies B.They are more efficient for studying rare diseases C. They allow you to study multiple outcomes of a single risk factor D.They are more efficient for studying diseases that have a long latency period (i.e., a long time between exposure and manifestation of disease)

A, B, D

Select more than one: In the definition of epidemiology, "determinants" generally includes: A. Agents B. Causes C. Control measures D. Risk factors E. Sources

A, B, D, E

A number of passengers on a cruise ship from Puerto Rico to the Panama Canal have recently developed a gastrointestinal illness compatible with norovirus (formerly called Norwalk-like virus). Testing for norovirus is not readily available in any nearby island, and the test takes several days even where available. Assuming you are the epidemiologist called on to board the ship and investigate this possible outbreak, your case definition should include, at a minimum: (Choose one best answer) A. Clinical criteria, plus specification of time, place, and person B. Clinical features, plus the exposure(s) you most suspect C. Suspect cases D. The nationally agreed standard case definition for disease reporting

A. A case definition for a field investigation should include clinical criteria, plus specification of time, place, and person. The case definition should be independent of the exposure you wish to evaluate. Depending on the availability of laboratory confirmation, certainty of diagnosis, and other factors, a case definition may or may not be developed for suspect cases. The nationally agreed standard case definition for disease reporting is usually quite specific, and usually does not include suspect or possible cases

The hallmark feature of an analytic epidemiologic study is: (Choose one best answer) A. Use of an appropriate comparison group B. Laboratory confirmation of the diagnosis C. Publication in a peer-reviewed journal D. Statistical analysis using logistic regression

A. The hallmark feature of an analytic epidemiologic study is use of an appropriate comparison group.

This diagram illustrates a study launched in January 2010 to investigate hepatitis C virus (HCV) occurrence among health care workers in Troy, New York. Each line represents an individual that was enrolled in the study and shows when they were enrolled as well as the duration of time they remained in the study. Additionally, the lines show when and how long individuals experienced the virus. Remember that even after treatment and recovery, individuals are at risk for HCV again. What is the prevalence for HCV in January 2010? A. 3/13 (23.1%) B. 2/13 (15.4%) C. 2/12 (16.7%) D. 3/12 (25.0%)

C

In the definition of epidemiology, "distribution" refers to: A. Who B. When C. Where D. Why E. All the above

E