Archive for year: 2023

Section 1: Definition of Epidemiology

https://www.cdc.gov/ophss/csels/dsepd/ss1978/lesson1/section1.html

Lesson 1: Introduction to Epidemiology

In fact, epidemiology is often described as the basic science of public health, and for good reason. First, epidemiology is a quantitative discipline that relies on a working knowledge of probability, statistics, and sound research methods. Second, epidemiology is a method of causal reasoning based on developing and testing hypotheses grounded in such scientific fields as biology, behavioral sciences, physics, and ergonomics to explain health-related behaviors, states, and events. However, epidemiology is not just a research activity but an integral component of public health, providing the foundation for directing practical and appropriate public health action based on this science and causal reasoning.(2)

A. Distribution

Epidemiology is concerned with the frequency and pattern of health events in a population:

a. Frequency refers not only to the number of health events such as the number of cases of meningitis or diabetes in a population, but also to the relationship of that number to the size of the population. The resulting rate allows epidemiologists to compare disease occurrence across different populations.

b. Pattern refers to the occurrence of health-related events by time, place, and person. Time patterns may be annual, seasonal, weekly, daily, hourly, weekday versus weekend, or any other breakdown of time that may influence disease or injury occurrence. Place patterns include geographic variation, urban/rural differences, and location of work sites or schools. Personal characteristics include demographic factors which may be related to risk of illness, injury, or disability such as age, sex, marital status, and socioeconomic status, as well as behaviors and environmental exposures.

Characterizing health events by time, place, and person are activities of descriptive epidemiology, discussed in more detail later in this lesson.

B. Determinants

Determinant: any factor, whether event, characteristic, or other definable entity, that brings about a change in a health condition or other defined characteristic.

Epidemiology is also used to search for determinants, which are the causes and other factors that influence the occurrence of disease and other health-related events. Epidemiologists assume that illness does not occur randomly in a population, but happens only when the right accumulation of risk factors or determinants exists in an individual. To search for these determinants, epidemiologists use analytic epidemiology or epidemiologic studies to provide the “Why” and “How” of such events. They assess whether groups with different rates of disease differ in their demographic characteristics, genetic or immunologic make-up, behaviors, environmental exposures, or other so-called potential risk factors. Ideally, the findings provide sufficient evidence to direct prompt and effective public health control and prevention measures.

C. Application

Epidemiology is not just “the study of” health in a population; it also involves applying the knowledge gained by the studies to community-based practice. Like the practice of medicine, the practice of epidemiology is both a science and an art. To make the proper diagnosis and prescribe appropriate treatment for a patient, the clinician combines medical (scientific) knowledge with experience, clinical judgment, and understanding of the patient. Similarly, the epidemiologist uses the scientific methods of descriptive and analytic epidemiology as well as experience, epidemiologic judgment, and understanding of local conditions in “diagnosing” the health of a community and proposing appropriate, practical, and acceptable public health interventions to control and prevent disease in the community.

Challenge 1: Below are three key terms taken from the definition of epidemiology, followed by a list of activities that an epidemiologist might perform. Match the term to the activity that best describes it. You should match only one term per activity.

Distribution

Determinants

Application

1. ____ Recommend that close contacts of a child recently reported with Hepatitis A receive a an injection of gamma-globulin.

2. Salmonella and those without.

____ Compare food histories between persons with a food poisoning caused by

3. ____ Graph the number of cases of congenital HIV infections by year for the country

4. ____ Compare frequency of brain cancer among anatomists with frequency in general population

5 ____ Tabulate the frequency of clinical signs, symptoms, and laboratory findings among children with chickenpox in Bridgeport, CT.

6. ____ Mark on a map the residences of all children suffering from with leukemia within 2 miles of a hospital incinerator.

Section 2: Historical Evolution of Epidemiology

https://www.cdc.gov/ophss/csels/dsepd/ss1978/lesson1/section2.html

Read the following passage and answer the questions below.

In the mid-1800s, an anesthesiologist named John Snow was conducting a series of investigations in London that warrant his being considered the “father of field epidemiology.” Twenty years before the development of the microscope, Snow conducted studies of cholera outbreaks both to discover the cause of disease and to prevent its recurrence. Because his work illustrates the classic sequence from descriptive epidemiology to hypothesis generation to hypothesis testing (analytic epidemiology) to application, two of his investigations will be described in detail.

Snow conducted one of his now famous studies in 1854 when an epidemic of cholera erupted in the Golden Square of London.(5) He began his investigation by determining where in this area persons with cholera lived and worked. He marked each residence on a map of the area, as shown in Figure 1.1. Today, this type of map, showing the geographic distribution of cases, is called a spot map.

Because Snow believed that water was a source of infection for cholera, he marked the location of water pumps on his spot map, then looked for a relationship between the distribution of households with cases of cholera and

Figure 1.1 Spot map of deaths from cholera in Golden Square area, London, 1854 (redrawn from original)

Source: Snow J. Snow on cholera. London: Humphrey Milford: Oxford University Press; 1936.

the location of pumps. He noticed that more case households clustered around Pump A, the Broad Street pump, than around Pump B or C. When he questioned residents who lived in the Golden Square area, he was told that they avoided Pump B because it was grossly contaminated, and that Pump C was located too inconveniently for most of them. From Figure 1.1 Spot map of deaths from cholera in Golden Square area, London, 1854 (redrawn from original) this information, Snow concluded that the Broad Street pump (Pump A) was the primary source of water and the most likely source of infection for most persons with cholera in the Golden Square area. He noted with curiosity, however, that no cases of cholera had occurred in a two-block area just to the east of the Broad Street pump. Upon investigating, Snow found a brewery located there with a deep well on the premises. Brewery workers got their water from this well, and also received a daily portion of malt liquor. Access to these uncontaminated rations could explain why none of the brewery’s employees contracted cholera.

To confirm that the Broad Street pump was the source of the epidemic, Snow gathered information on where persons with cholera had obtained their water. Consumption of water from the Broad Street pump was the one common factor among the cholera patients. After Snow presented his findings to municipal officials, the handle of the pump was removed and the outbreak ended. The site of the pump is now marked by a plaque mounted on the wall outside of the appropriately named John Snow Pub.

Briefly explain (in 2-3 sentences) how epidemiologist John Snow discovered the origin of the cholera outbreak in 1854, London.

Look at the map. From this information, Snow was able to deduce the primary source of contaminated water and the most likely source of infection for most persons with cholera in the Golden Square area. How did he make this determination?

He noted with curiosity, however, that no cases of cholera had occurred in one area in the Golden Square area. Upon investigating, Snow found a brewery located there with a deep well on the premises. Brewery workers got their water from this well, and also received a daily portion of malt liquor. Access to these uncontaminated rations could explain why none of the brewery’s employees contracted cholera. Where was the brewery?

Section 4: Core Epidemiologic Functions

https://www.cdc.gov/ophss/csels/dsepd/ss1978/lesson1/section4.html

The following are Core Functions used by epidemiologists to solve epidemics. An example of each is given below.

Public health surveillance

Field investigation

Analytic studies

Evaluation

E. Linkages

F. Policy development

A. Public health surveillance Reviewing reports of test results for Chlamydia trachomatis from public health clinics

B. Field investigation Interviewing persons infected with Chlamydia to identify their sex partners

C. Analytic studies Comparing persons with symptomatic versus asymptomatic Chlamydia infection to iden- tify predictors

D. Evaluation Conducting an analysis of patient flow at the public health clinic to determine waiting times for clinic patients

E. Linkages Meeting with directors of family planning clinics and college health clinics to discuss Chlamydia testing and reporting

F. Policy development

Developing guidelines/criteria about which patients coming to the clinic should be screened (tested) for Chlamydia infection

Challenge 3: Your goal is to go back to Section 2 above, read the description of John Snow’s research on the cholera epidemic. Now identify an example of each of these core epidemiological functions that Snow used in his study. Choose 3 of the 6 Core Functions.

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Worksheet for Light Spectrum and Plant Growth Lab

Page 1 of 2

Instructions:

· Go to the following Virtual Lab Website http://www.glencoe.com/sites/common_assets/science/virtual_labs/LS12/LS12.html

· The virtual lab runs under Flash. You may need to enable your browser to run it.

· Watch the short video clip about the white light spectrum and the pigments in plants.

· Using the controls to run the experiment, collect data to fill in the tables for radish and lettuce.

· Select a plant

· Select the color for each chamber

· Turn the light switch “On” to run the experiment

· Use your mouse to grab the ruler and measure the height of the tallest part of the plant to the nearest centimeter. The height of each plant counts as one observation.

· Record the data in the appropriate data table.

· Calculate the average height of the plant for each color.

Table for Spinach (already filled out)

TABLES TO FILL OUT

1. Table for Radish

2. Table for Lettuce

QUESTIONS TO ANSWER

3. Based on these observations, which color of light causes the greatest amount of plant growth?

4. Based on these observations, which color of light causes the least amount of plant growth?

5. In a short paragraph, explain how these observations are consistent with the information presented in the short video?

6. Given that white light contains all colors of the spectrum, what growth results would you expect under white light?

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Monhybrid and Dihybrid Crosses – Introduction

Mendel crossed true-breeding pea plants in order to develop and understanding of how traits are inherited. True-breeding means that if a plant was crossed with itself, it always generated offspring that looked like the parent. Although Mendel didn’t know this at the time, it meant that the parent plant was homozygous or had two copies of the same allele that controlled the appearance of the trait.

Mendel noticed that when he crossed two true-breeding plants exhibiting different versions of a trait (e.g., green and yellow); the offspring (F1) always looked like only one of the parent plants. We know now that the F1 individuals looked like the parent that carried the dominant trait. But what surprised Mendel, was that when he crossed the F1 individuals with each other, the F2 offspring exhibited BOTH traits! Based on this observation, he concluded that the F1 individuals were hybrids, meaning they carried both alleles for a given trait. Only the dominant trait was expressed in the F1 individuals and the recessive trait, although present, was masked.

A monohybrid cross is when you are interested in crossing individuals that vary in only a single trait (e.g., flower color, seed color, stem length). In a dihybrid cross, we are crossing individuals that differ at two traits (e.g., flower color and seed color, flower color and stem length). Obviously, the more traits that vary, the more complex the crosses become!

By examining the distribution of the various traits obtained following different types of crosses, Mendel was able to describe the general pattern of genetic inheritance. Be sure to review the online lecture this unit on Genetics and pp 146-153 in your book before starting these first two exercises.

We will be using the following website for the first exercise. Be sure that you can access it and use it before beginning:

Fly Lab JS (Links to an external site.)

You will need to complete the Tables and answer the questions in the Unit 6 Experiment Answer Sheet for Exercises 1 and 2.

Inheritance of Human Traits – Introduction

Some human traits are controlled by a single gene that has only two alternative alleles. If a characteristic is determined by the dominant allele, one or both parents express that trait and many of the children will as well. Dominant characteristics will most likely be present in every generation, since the expression of these traits requires only one of the dominant alleles in order to be expressed. If the characteristic is determined by the recessive allele, then neither parent may express the trait nor few of the children. This is because two copies of the recessive allele must be present in order for the recessive trait to be expressed. If a trait is X-linked recessive; meaning the gene for the trait is found on the X chromosome, it will be expressed primarily in males.

The application of human genotypes in medicine and genetic counseling is becoming more and more necessary as we discover more about the human genome. Despite our increasing ability to decipher the chromosomes and their genes, an accurate family history remains one of the best sources of information concerning the individual. In this exercise you will determine your genotype for certain characteristics that are controlled by a single gene with two alleles based on your phenotype. We will not be looking at any X-linked traits in this exercise.

Use the information about the traits of interest in the Unit 6 Experiment Answer Sheet to answer the questions found there.

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The Decline and fall of Enron

The merging of Enron of InterNorth Inc. in Ohama and Natural Gas Co. in Houston in 1985 formed the Enron Company. Following the merging, the company was rebranded to energy trader and supplier by the chief executive officer (CEO). Enron took advantage of the deregulation of energy which allowed companies to predict the future prices of oil. Consequently, Enron flourished and at the end of the 1990s its shares were its shares were worth $90.75. However, by December 2001, the company was declared bankrupt and the shares worth had declined to $0.26. Its fall affected thousands of employees and strongly shook the Wall Street.

Many economists believe that the exposed criminality in Enron that was admissible in the court of law was the cause of the decline and fall of the company. However, the true cause of the fall was selfishness by company management that applied some legally acceptable half-truths including equating value to shareholder value, the view of a man as economic man, the view of the society as a rising tide of prosperity and the view of leadership as heroic.

Worldwide, there has been a belief that every man is ‘economic man’. Through this belief, man has grown to be self-centered obsessed with increasing personal gains at the expense of others. The belief of economic man brings a wedge of distrust into society (Mintzberg, Robert and Kunal 67). Everyone can only do things for themselves and not for the society. This kind of individualism leads to failure since we are living as individuals but in a social setting. Companies must contribute to the development of the society to enhance their development. Disconnecting from the society will lead to their failure as they operate in a social space.

Establishment of the corporations was meant to benefit the society. However, the rhythm has changed to benefit the shareholders disregarding all other stakeholders (Mintzberg, Robert and Kunal 67). Employees bear the greatest pressure in creating the economic performance yet the large share of the profit is divided among the shareholders. Consequently, the employees feel demotivated to work and disconnected to the top management leading to poor productivity. This eventually results in company fall.

In many corporations, the shareholders are passively creating a need for heroic leaders. The chief executives are employed as the representatives of the shareholders, and in return, they are rewarded huge amount of money for the performance on behalf of the entire enterprise. Supporting this act is the assumption that equates the chief executive to the enterprise and deemed responsible for the entire performance (Mintzberg, Robert and Kunal 67). In an attempt to fit the heroic images, the chief executives promise grand results at the expense of the other employees. Heroic leadership leads to disconnection of the top leaders and every other employee. Lose of connection discourages teamwork and self-motivation leading to eventual fall of the corporation.

An effective organization is considered to be lean and mean. It has the meaning that the company should do more with less and should achieve a win-win situation. Simply, it means lower costs, increased productivity, happier customers, and flatter structures (Mintzberg, Robert and Kunal 67). Through the application of the lean and mean principle, many companies have laid off many employees in an attempt to minimize cost while optimizing profit. This has resulted in burned-out managers, disgruntled customers, angry workers, and quality loss. Reduced job security has resulted in a feeling of betrayal among the employees and hence reduced productivity in the long run.

There is a tendency of every individual wanting to prosper in the society. There has been rhetoric by those in high position that everyone prospers in a selfish economy. However, the saying is meant to fuel their selfish motives by the rich at the expense of the poor. Prosperity has to be both economically and socially and cannot be measured by an increase in economic values only (Mintzberg, Robert and Kunal 67). Economic progression coupled with social regression leads to failure of corporations.

The deregulation of energy market became the turning point of the Enron Company. Due to this the company flourished and by 1990 the company had reached its peak. However, this was followed by a drastic fall and by 2002 the company was declared bankruptcy. The fall of Enron caused havoc in the entire Wall Street. Many economists could not understand how such a big company could collapse overnight. However, the failure of the company started soon the company adopted policies that self-centered without considering their sustainability.

Works Cited

Mintzberg, Henry, Robert Simons, and Kunal Basu. “Beyond selfishness.” MIT Sloan Management Review 44.1 (2002): 67.

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