Microbiology Lab

Morbidity and Mortality Weekly Report (MMWR) Assignment

Taken from Leboffe and Pierce, Microbiology: Laboratory Theory and Application, 4^th Edition, 2015 Morton Publishing Company.

Epidemiology is the study of the causes, occurrence, and transmission, distribution and prevention of diseases in a population. The Centers for Disease Control and Prevention (CDC) in Atlanta, Georgia, is the national clearinghouse for epidemiological data. The CDC receives reports related to the occurrence of 30 notifiable diseases from the United States and its territories, and compiles the data into tabular form, available in the publication Morbidity and Mortality Weekly Report (MMWR).

Two important disease measures that epidemiologists collect are morbidity (sickness) and mortality (death). Morbidity relative to a specific disease is the number of susceptible people who have the disease within a defined population during a specific time period. It usually is expressed as a rate. Because population size fluctuates constantly, it is conventional to use the population size at the midpoint of the study period. Also, the units for the rate fraction are “cases per person” and usually are small decimal fractions. To make the calculated rate more “user-friendly,“ it is multiplied by some power of 10 (“K”)to achieve a value that is a whole number. Thus, a morbidity rate of 0.00002 is multiplied by 100,000 (10⁵) so it can be reported as 2 cases per 100,000 people rather than 0.00002 cases per person. Morbidity rate is calculated using the following equation:

Morbidity rate =

Mortality, also expressed as a rate, is the number of people who die from a specific disease out of the total population afflicted with that disease in a specified time period. It, too, is multiplied by a factor “K” so the rate can be reported as a whole number of cases. The equation is

Mortality rate =

Minimally, an epidemiological study evaluates morbidity or mortality data in terms of person (age, sex. Race, etc.), place, and time. Sophisticated analyses requires training in biostatistics, but the simple epidemiological calculation you will be doing can be performed with little mathematical background. You will calculate incidence rate, which is the occurrence of new cases of a disease within a defined population during a specific period of time. As before, “K” is some power of 10 so the rate can be reported as a whole number of cases.

Incidence Rate =

Because our focus is microbiology, we will deal only with infectious diseases = those caused by biological agents such as bacteria and viruses. Noninfectious diseases, such as stroke, heart disease, and emphysema, also are studied by epidemiologists but are not within the scope of microbiology.

An understanding of the causes and distribution of diseases in a population is useful to health-care providers in a couple of ways. First, awareness of what diseases are prevalent during a certain period of time aids in diagnosis. Second, an understanding of the disease, its causes and transmission can be useful in implementing strategies for preventing it.

PROCEDURE

You will need a computer with Internet access to retrieve the Morbidity and Mortality Weekly Reports.

1. Choose a disease from the table, and record its name on the data sheet
2. Go to CDC website (http://www.cdc.gov). Then follow these links
   1. Scroll to the lower third of the page. Click on Morbidity and Mortality Weekly Report under “Science at CDC”.
   2. Click on the “All Reports” square.
   3. On the menu bar on the left click on “Weekly Report”
   4. Click on “Past Volumes (1982-2019)”
   5. Click on the link to the volume with the most recent complete year (2019).
   6. The first paragraph on the top of the page reads:

Click on the link within the paragraph.

1. This link leads to a page where you will see this box. Click on “Weekly and annual tables”
2. On the next page, you will find three tabs:
   1. Click on Interpreting Data: save/bookmark Readers’ Guide: Understanding Weekly and Annual NNDSS WONDER Tablesand Notification requirements for National Notifiable Conditions. You will use the information when writing the report
   2. Click on CDC WONDER in the Weekly Tables tab. It opens up another page with links to a bunch of tables. On the right side, click on a box like this:
3. Change the year and week to 2019 Week 1.
4. You will see a list of a bunch of tables. Find the Table that has your chosen disease in it. They are organized alphabetically. See list of diseases in table 1 below.
5. Now start gathering your data.
6. You should see something like this

3. The diseases are listed alphabetically. The orange circles indicate the disease name. I put in the circles, so don’t expect them on your screen.
4. Write down the current week’s occurrences as well as the total number of cases in the United States in 2019 and 2018 (the number in columns Cum YTD 2019 and Cum YTD 2018)
5. Return to page with the links to all the tables from the last week (Hit back button once).
6. Hit the NEXT button on the right to advance to the next week in 2018, and collect your next set of data.
7. Record cumulative numbers for the United States in 2018 and 2019 in your data table. Because they are cumulative totals, they should be greater than or equal to the preceding week. Nevertheless, because the reported numbers are provisional and subject to change, this may not always be the case. Simply record the numbers from the CDC website as they are reported.
8. And repeat 6-9 for 52 weeks. (Yes, this will take you some time.)
9. As you are collecting the data scroll down and see if there are higher incidences of the disease associated with season of the year, population density and geographical region.
10. Answer the questions and complete the activities on the data sheet.
11. At some point before the assignment is due, go to the National Notifiable Diseases Surveillance System (NNDSS) page (http://wwwn.cdc.gov/nndss/) and read the information on the home page. Then, click the link to “Data Collection and Reporting” to see how the data you are using have been collected.

Table 1. Notifiable Diseases in the United States and its Territories Posted in Table II of MMWR of the CDC. Not all diseases have a high incidence, but similar number may not make the work any easier.

DATA TABLE

After you gather the data from the CDC website, you can enter it into an Excel spreadsheet and make your life oh-so easy. OR you can calculate by hand calculator and graph on graphing paper. (You will have to scan the pages and submit via TurnItIn.)

1. Calculate the number of new cases during each 4-week period (weeks 1-4, weeks 5-8, etc.) for both years by subtracting the total at the end of a 4-week period from the total at the end of the next 4-week period. This is, for the second 4 weeks subtract the total at the end of week 4 from the end of week 8. Record thesein the table (“4-week total”). Show sample calculations for the third 4-week totals of both years in the space below.

2. Calculate national incidence values of each 4-week period during the two years using the calculated 4-week totals in the numerator. Use the U.S. population size on July 1 in the denominator. This value can be obtained from the U.S. Census Bureau website at http://www.census.gov/popest/. Population estimates for the entire US on July 1, 2019was 328,239,523and on July 1 2018 was 327,167,434.

Calculate the incidence rate for each 4-week period.

Incidence Rate =

Show sample calculations for the third 4-week totals of both years in the space below.

3. Finally, write a report on the infectious disease and its rate of incidence in the United States over two years. The report should include:
   1. Title page – 2 points
      1. Short, but specific and informative. Your title should reflect the main objective of this assignment. Please do not call it “Lab Report 2”. Be creative, but be accurate.
   2. Introduction-12 points(Cite your referencesand list in a reference section at the end of the paper.In general, don’t use quotes.).
      1. Name of the disease
      2. Name of causative agent by scientific name

• Is it a bacterium, virus, protozoan or rickettsia?

1. The pathogen and it’s environment, its life cycle
2. Sources of infection and risk factors
3. Illness and symptoms

• Diagnosis and detection
• Treatment. Is there a vaccine available?

1. Prevention and control
2. Look up and using your own words define the following concepts for determining the level of the disease:
   1. Endemic
   2. Hyperendemic
   3. Sporadic
   4. Epidemic
   5. Outbreak
   6. Pandemic
3. Data collection and publication – 8 points
   1. Read the information in the Readers’ Guide: Understanding Weekly and Annual NNDSS WONDER Tables. In your own words explain how the CDC collects the information on the number of cases and surveils diseases.
   2. Look up in Notification requirements for National Notifiable Conditions your chosen disease and report what is its notification timeline and what does it mean (the description is at the top of the page). Also mention what type of cases require notification.
4. Results – 12 points
   1. Show sample calculations 1 (4 week totals) and 2 (incident rates)
   2. Present your chosen disease data table with the cumulative numbers and incidence values for the United States in 2018 and 2019. Table should be numbered (Table I) and have a title.

• Prepare a graph that illustrates the cumulative data for each week over the two years. Be sure to include a title, axis labels with appropriate units, and legend in your graph.

1. Graph the calculated national incidence values over the two years studied. Again, be sure to include a title, axis labels with units, and legend.

1. Discussion and conclusions – 12 points.Be clear and give your this section some thought!
   2019. What can you tell from your Table I data and your graphs? Compare 2018 and 2019.
   2020. Is the disease endemic, sporadic or were there outbreaks or epidemics? These guidelines may be useful: https://www.cdc.gov/csels/dsepd/ss1978/lesson1/section11.html

• Associate any increase in reported cases with season of the year, population density and geographical region (look up the regions of the US in the original CDC tables). For example, Lyme disease is very prevalent in New England and people contract it mostly during spring and summer, however it may take some time before they have a diagnosis.

1. References – 4 points
   1. List any literature that you cited in the report. List the references in alphabetical order by the last name of the primary author.
   2. Include in your references the CDC’s the weekly report tables:

Centers for Disease Control and Prevention. National Notifiable Diseases Surveillance System, Weekly Tables of Infectious Disease Data. Atlanta, GA. CDC Division of Health Informatics and Surveillance. Available at: https://www.cdc.gov/nndss/infectious-tables.html.

1. 4 pages max. excluding data tables, graphs, and list of references; 12 point Times Roman
2. Submit via TurnItInby April24, one minute before mid-night.

Grading Rubric:

aTitle page (2 points)

bIntroduction (12 points)

• Were these concepts included in the introduction?
  1. Name of the disease
  2. Name of causative agent by scientific name

• Is it a bacterium, virus, protozoan or rickettsia?

1. The pathogen and it’s environment, its life cycle
2. Sources of infection and risk factors
3. Illness and symptoms

• Diagnosis and detection
• Treatment. Is there a vaccine available?

1. Prevention and control
2. Look up and using your own words define the following concepts for determining the level of the disease:
   1. Endemic
   2. Hyperendemic
   3. Sporadic
   4. Epidemic
   5. Outbreak
   6. Pandemic

• Sources cited in references.
• Proper use of vocabulary, sentence structure and overall flow

c Data collection and publication (8 points)

• Shows understanding on how the CDC collects data and publishes it and what are the notification timelines.
• Uses own words to explain it
• Proper use of vocabulary, sentence structure and overall flow

d Results (12 points)

• Sample calculations are included
• Table has a title
• Graphs have a title, axis labels with units, and legend.

e Discussion and conclusions (12 points)

• Comparison between 2018 and 2019
• Were there years with outbreaks, is it an endemic disease?
• Associations of endemic conditions or outbreaks with seasons, geography and population density?
• Shows that spent time giving it thought
• Proper use of vocabulary, sentence structure and overall flow

f References (4 points)

• Any literature cited in the report is listed.
• References listed in alphabetical order by the last name of the primary author.
• CDC reference listed