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1.4.3 – Life of an epidemiologist

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1 1.4.3 – Life of an epidemiologist
Mrs. Stewart Medical Interventions

2 First Incident In March 1985, a nurse epidemiologist in a county health department noted, while reviewing surveillance data, three cases in a single month of hepatitis B of unusual origin. Hepatitis B, or serum hepatitis, is transmitted through sexual contact and by exposure to infected bodily fluids, but these three patients did not seem to have the usual risk factors. All three people did, however, indicate having received injections at the same health care facility. The nurse's immediate questions were: Is this a coincidence? Did these three cases occur by chance or is there a link? In this instance, the nurse decided to pursue an investigation.

3 Second Incident At 8:30 in the morning on August 2, 1976, Dr. Robert B. Craven of CDC's Viral Diseases Division received a call from a nurse at a Veterans' Hospital in Philadelphia, Pennsylvania. The nurse reported two cases of severe respiratory illness, one of which had been fatal. Both people had attended the annual American Legion Convention held July By the evening of August 2, 71 more of the people attending the convention had the same illness, with symptoms of acute onset of fever, chills, headache, malaise, dry cough, and myalgia. Further conversations with local and state public health officials revealed that between July 26 and August 2, 18 conventioneers had died. Deaths were due primarily to pneumonia.  An intense investigation began immediately. The incident became known as the first outbreak of Legionnaires' disease and led to the discovery of the gram-negative pathogen, Legionnella pneumophila.

4 Third Incident On October 30, 1989, a New Mexico physician notified the state's health department of three patients with marked peripheral eosinophilia and severe myalgia. All three patients had been taking oral preparations of L-tryptophan, a nonprescription drug sold as a dietary supplement in health food stores. Despite extensive clinical evaluation and testing, the illness could not be identified.  An investigation followed and resulted in the characterization of eosinophilia- myalgia syndrome, EMS. The investigation implicated a vehicle for exposure—L- tryptophan dietary supplements—before a suspected agent was identified, and the product was taken off the market. Eventually, the problem was traced to a contaminant that had been introduced by changes in the production process at a single manufacturing facility. These three examples illustrate some of the key reasons for needing applied, or field, epidemiology: They were unexpected. They demanded a response. The investigators had to go out into the field to solve the problem.

5 Epidemiologist Career Journal
Master’s degree required Average Salary ~ 63,000 / year or $30.30 / hour Assignment: list at least 10 duties for an epidemiologist Reflection: Would you become an epidemiologist? Why or why not?

6 1854 Outbreak 1831 – 1853 Cholera outbreaks all over Europe and London It was believed to be spread through the air 0ver 10,000 died Soho 1800’s – slaughter houses, cow sheds, animal droppings August 1854 – Broadstreet area Major Cholera outbreak By September 10th – 500+ people had died

7 John Snow Anesthesiologist in NY during 1854 outbreak
Realized the broad street pump was common factor among all sick with cholera Removed pump which severely decreased outbreak “Father of epidemiology”

8 Cholera Cause: Bacteria - Vibrio cholerae
Symptoms: acute intestinal infection causing profuse watery diarrhea, vomiting, circulatory collapse and shock. Left untreated – 25-50% cases are fatal Recent: countries, 589,854 cases and 7,816 deaths Transmission: Found in water contaminated by feces & on raw shellfish Prevention: Treated water (boiled or chlorine) and modern sewage systems

9 Mission: Assume the role of an epidemiologist
Approach and address the following outbreak scenario

10 Task #1 Working as an epidemiologist, you are called in to a small, rural middle school. Over fifty students have reported to the nurse in the last three hours, complaining of nausea and vomiting. What do you want/need to know? List 5 questions you want to ask List ways you will gather answers to your questions

11 New Information This all occurred from 12:30 – 3:30
Everyone who was sick had already eaten lunch Everyone who was sick ate the school lunch Now, what do you want to know? List 5 new questions.

12 Task #2 Given the severe gastrointestinal symptoms of the students, you suspect a food-borne pathogen. Something they ate is making these kids extremely sick Interview the students about foods eaten from cafeteria Assignment: Use info to calculate Attack Rates

13 Number of people who ate a certain food and became ill
45/69 = 65% 20/31 = 65% 10/58 = 17% 40/64 = 63% 43/53 = 81% 18/28 = 64% 36/59 = 61% Attack Rate = Number of people who ate a certain food and became ill _____________________________________________ Total number of people who ate that food

14 Assignment: Hypothesize:
Determine which food product you think is responsible for this outbreak Look up the most common food-borne pathogen (in the United States) for that food product Describe how to treat this pathogen Treat symptoms only? Other treatment required?

15 Complete the Task You have: You need to: Identified the source
Treated those infected You need to: Stop the outbreak from spreading List 3 ways to stop this from continuing to infect others Prevent it from happening again List 3 ways to prevent it

16 Choose a disease Tuberculosis Hantavirus pulmonary syndrome (HPS)
Mad cow disease Avian influenza (bird flu) Malaria Lyme disease Cervical cancer Legionnaire disease Plague Measles Ebola hemorrhagic fever AIDS Smallpox Polio Anthrax West Nile Virus SARS

17 Assignment Choose one of the following items to complete:
Write a short paragraph describing how you are working to prevent this disease. Make sure to mention your geographical location and to describe how the action or medication works to prevent this disease. Describe any barriers you encounter in delivering health care that are unique to your situation. Write a short paragraph describing your efforts in treating the disease or designing a new therapy. Make sure to mention how this treatment stops the symptoms of the disease or cures the patient. Describe any barriers you encounter in delivering health care that are unique to your situation.

18 1.4.3 Conclusion Questions Describe at least four ways an epidemiologist could have helped in handling and analyzing the outbreak of hemorrhagic fever in Africa. How do epidemiologists play a role in the diagnosis, treatment, and prevention of chronic illnesses, such as cancer or heart disease? Explain why statistics and math are important tools for an epidemiologist.

19 Task #3 – Other responsibilities
Epidemiologists organize formal studies to test the possible associations between risk factors and disease. Not all epidemiologists study infectious diseases or investigate outbreaks. Many epidemiologists study the factors that may contribute to the development of chronic diseases such as cancer and heart disease. The most common study designs utilized by epidemiologists to investigate both infectious and chronic diseases are the cohort study and the case-control study.

20 Cohort vs. Case-Control Study
In a cohort study (also called a prospective study), the investigator selects a group of exposed individuals (individuals who have been exposed to the potential risk factor) and a group of non-exposed individuals and follows both groups over time to determine the incidence of disease. In a case-control study (also called a retrospective study), a group of individuals with the disease are identified (called cases) and compared to a group of people without the disease (called controls). Cases and controls are carefully matched on all criteria other than the one being studied. For example, cases and controls should be matched for age, gender or for underlying medical conditions. These individuals can then be surveyed about their exposure to the given risk factor.

21 Assignment Describe how you would set up both a case-control and a cohort study looking at the link between smoking and elevated cholesterol levels. For each study design, include information about the participants in the study and describe how you might analyze study data. Answer Conclusion questions 2-6.


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