• To Kill A Mockingbird Study Guide Questions

Outbreak Investigations Outbreak Investigations Introduction An outbreak is essentially the same thing as an epidemic, i.e., an increased frequency of a disease above the usual rate (endemic rate) in a given population or geographic area. Pandemic refers to simultaneous epidemics occurring in multiple locations across the globe. Traditionally, these terms referred to infectious diseases, but they can also be used to describe non-infectious diseases and chronic conditions, such as lung cancer and obesity. In addition, the principles of investigation are similar for all of these. This module provides a practical introduction to the steps involved in outbreak investigations, and it provides some useful tools. Learning Objectives After successfully completing this section, the student will be able to:.

Define the terms outbreak, epidemic, endemic, and pandemic. List the steps in the investigation of an outbreak. Given the initial information of a possible disease outbreak, describe how to determine whether an epidemic exists. Describe the importance of having a case definition and the factors to consider in developing a case definition.

Explain how to gather, record, and analyze descriptive data related to characteristics of person, place, and time that will generate hypotheses about the source of an outbreak. Define the primary difference between descriptive studies and analytical studies. Create a 'line listing' using an Excel spreadsheet. Define and calculate prevalence and incidence.

Define and calculate a) mortality rate, b) morbidity rate, c) attack rate, d) case-fatality rate. Perform basic functions in Excel, including: - Labeling columns and rows & entering text and numeric data.

Sorting data. Using Excel functions to tabulate data using the COUNT and SUM functions to tabulate data. Identify the following types of epidemic curves: a) point source epidemic, b) continuous source epidemic, and c) propagated source epidemic. Distinguish between cohort studies and case-control studies, be able to describe their key features, and be able to give an example of each. Calculate and interpret a risk ratio for a cohort study. Calculate and interpret an odds ratio for a case-control study.

Demonstrate how to use the provided Excel worksheets to perform a statistical analysis for either a cohort study or a case-control study, including calculation and interpretation of p-values and 95% confidence intervals. A Salmonella Outbreak after a School Luncheon – A Cohort Study. Use the Excel skills outlined above to analyze the line listing data to identify the food that was responsible. Calculate and interpret relative risks, p-values, and 95% confidence intervals. Interpret your analysis of the outbreak and discuss how your analysis relates to the official report of the study conducted by the Massachusetts Department of Public Health.

Discuss how you would explain these results to concerned citizens who had no knowledge of epidemiology. The Hepatitis A Outbreak in Marshfield, MA – A Case-Control Study. Create and interpret the epidemic curve for the hepatitis A outbreak.

Use the Excel skills outlined above to analyze the line listing data from the hepatitis A outbreak, including odds ratios, p-values, and 95% confidence intervals. Interpret your analysis of the hepatitis outbreak and discuss how your analysis relates to the official report of the study conducted by the Massachusetts Department of Public Health. Discuss how you would explain these results to concerned citizens who had no knowledge of epidemiology. Identifying Outbreaks Outbreaks generally come to the attention of state or local health departments in one of two ways:. Astute individuals (citizens, physicians, nurses, laboratory workers) will sometimes notice cases of disease occurring close together with respect to time and/or location or they will notice several individuals with unusual features of disease and report them to health authorities. Public health surveillance systems collect data on 'reportable diseases'. Requirements for reporting infectious diseases in Massachusetts are described in 105 CMR 300.000 (Reportable Diseases, Surveillance, and Isolation and Quarantine Requirements).

The Massachusetts Virtual Epidemiologic Network (MAVEN) is a new web-based disease surveillance and case management system that enables MDPH and local health departments to capture and transfer appropriate public health, laboratory, and clinical data efficiently and securely over the Internet in real-time. In addition, disease registries, such as the Massachusetts Cancer Registry, are also important components of the public health surveillance system. For more information, see the online learning module on Surveillance.

Why Investigate Outbreaks? The primary reason for conducting outbreak investigations is to identify the source in order to establish control and to institute measures that will prevent future episodes of disease. They are also sometimes undertaken to train new personnel or to learn more about the disease and its mechanisms for transmission. Whether an outbreak investigation will be conducted may also be influenced by the severity of the disease, the potential for spread, the availability of resources, and sometimes by political considerations or the level of concern among the general public. Steps in the Investigation of a Disease Outbreak Most outbreak investigations involve the following steps:. Preparation for the investigation. Verifying the diagnosis and establishing the existence of an outbreak.

To Kill A Mockingbird Study Guide Questions

Establishing a case definition and finding cases. Conducting descriptive epidemiology to determine the personal characteristics of the cases, changes in disease frequency over time, and differences in disease frequency based on location. Developing hypotheses about the cause or source. Evaluating the hypotheses & refining the hypotheses and conducting additional studies if necessary. Implementing control and prevention measures.

Communicating the findings Some of the steps may be conducted simultaneously, and the order may vary depending on the circumstances. For example, if new cases are continuing to occur and there are steps that can be taken to control the outbreak and prevent more cases, then certainly control and prevention measures would take top priority. Step 1: Prepare for the Investigation Before embarking on an outbreak investigation, consider necessary preparations:. If the disease is known, research it paying particular attention to symptoms, case definitions, modes of transmission, diagnostic tests, control measures, etc.

Quickly make yourself knowledgeable about the disease. There are many excellent online resources:. The Massachusetts Guide to Surveillance, Reporting and Control. The MDPH communicable disease Factsheets. The CDC's Case Definitions for Infectious Conditions Under Public Health Surveillance. The CDC's Case Definitions for Chemical Poisoning. The CDC index to Diseases and Conditions and.

The CDC's index of Parasitic Diseases. You should also make a list of necessary supplies and equipment and make sure you have everything you will need. Since outbreak investigations frequently involve multiple agencies and jurisdictions, coordinate with them to clarify your role in the investigation and establish contacts. Step 2: Verify the Diagnosis & Presence of an Outbreak We noted that an outbreak is an increase in the frequency of a disease above what is expected in a given population.

However, an apparent outbreak can result from either incorrect diagnoses, multiple diseases with similar symptoms, or even changes in record keeping or surveillance practices. It is important to establish that the outbreak is real by examining how the cases were diagnosed and by determining what the baseline rate of disease was previously. For reportable diseases, baseline rates of disease (i.e., the usual or expected rate) can be determined from surveillance data, and you can compare rates during the previous month or weeks with the current rates of disease. For non-reportable diseases or conditions you may be able to find baseline data from state or national vital statistics, from disease registries, or from hospital discharge records, such as the Massachusetts Health Data Consortium. If you have detailed data on the number of cases of disease over time, an epidemic curve is an informative way to display this data graphically, and an epidemic curve can also provide clues about the source of infectious disease outbreaks, as we will see later.

Be aware that apparent changes in disease frequency can result from:. Changes in case definitions or changes in local reporting procedures. Increased interest in a disease because of local or national awareness might result in greater scrutiny by health care workers or more frequent requests from patients for exams and diagnostic procedures. Improvements or changes in diagnostic or screening procedures (e.g. Introduction of the prostate-specific antigen test for prostate cancer resulted in an apparent increase in the frequency of prostate cancer). Sudden changes in the size or composition of the population (e.g., students returning to school in the fall or an influx of migrant workers) Laboratory testing can be important for several reasons:. It can provide verification of the diagnosis.

It is not necessary or feasible to confirm the diagnosis all cases, but verification in at least a subset is important. It is also important to verify that lab results are consistent with the signs and symptoms that were reported. For bacterial diseases DNA fingerprinting through Pulsed Gel Field Electrophoresis (PGFE) can be extremely helpful in establishing that cases were exposed to the same strain of bacterium and, presumably, from the same source. PGFE can be particularly useful as a way on connecting cases that are geographically far apart, for example, during multi-state outbreaks. Once PGFE is conducted, the data are entered into PulseNet, an electronic database created through a collaboration between CDC and the Association of Public Health Laboratories (APHL). Serological tests can also be valuable.

For example, with hepatitis A infection (a virus) there is a well characterized pattern of changes in serological tests that not only establish that an individual has been infected with hepatitis A virus, but can also distinguish between recent (or pre clinical) infections and infections that occurred in the past. This is illustrated in the figure below, which illustrates changes in anti-HAV (hepatitis A virus) antibodies over time after an acute infection. Anti-HAV antibodies of the IgM class rise very promptly after infection with the virus, even before symptoms occur. Over time IgM anti-HAV antibodies decline and are progressively replaced by the anti-HAV IgG antibodies that confer long-lasting immunity to HAV. Therefore, high titers of IgM anti-HAV indicate recent infection, while high titers of IgG anti-HAV indicate that the individual was infected in the past and is now immune.

For more detailed instruction on the use of serological tests for hepatitis, please see CDC's Online Serology Training. For more information on laboratory testing see the following from the Focus on Epidemiology series:.

Laboratory Diagnosis: An Overview. Laboratory Diagnosis in Outbreak Investigations. Collecting Specimens in Outbreak Investigations. Laboratory Diagnosis: Molecular Techniques Step 3: Establish a Case Definition; Identify Cases Case Definitions By a case definition we mean the standard criteria for categorizing an individual as a case. Establishing a case definition (the criteria that need to be met in order to be considered 'a case') can be tricky, particularly in the initial phases of the investigation.

You want your definition to specific enough to identify true cases of disease, but you also want it to be broad enough and sensitive enough that it will identify most, if not all of the cases. As a result, the case definition may change during the investigation. In the earliest stages, it might be broader and less specific in order to make sure you identify all of the potential cases ('possible' cases), but later on, it might include more specific clinical or laboratory criteria that enable you to categorize individuals as 'probable' or 'confirmed' cases. Case definitions may include four types of information:. clinical information such as symptoms or lab results, e.g.

. What should the Mubanda health minister do? The options mentioned in the case are listed below:. Divert what resources she could from HIV/AIDS programs to buy supplies of Holizan at the current global price of $450 per regiment. Ask Rosendahl to make supplies of Holizan available free or at production cost. Arrange with a generic drug firm in South Africa to produce a Holizan equivalent without permission form or payment to Rosendahl. Wait and see how the crisis develops.

What should Rosendahl's CEO Elliott do, knowing that he has no control over the production of generic Holizan in Africa?. Pharma and Stakeholders: What obligations do pharmaceutical companies have to their stock holders and development financers?

What responsibilities, if any, does the pharmaceutical industry have to both the local and global communities?. What is a 'fair' price for Holizan? In answering this question, consider what is fair to Rosendahl, Rosendahl's stock holders, and the people of Mubanda. Should Rosendahl provide Holizan for free? At production cost? At a price that will cover development costs to break even?

At a price that will turn a profit. When should countries be able to violate patent rights?.

What do you think of the WTO rules?. What do you think of Celine Charvariet of OXFAM's statement that 'poverty alone in the third world ought to justify violating patent rights on a very broad set of drugs'?. How will WTO patent rules affect new R&D on pharmaceuticals for the third world? July 2010 Jul 1, 2010.