Flu Tracking (Part 1/3)
Lesson 7 of 11
Objective: Students will analyze past and present influenza data to determine how epidemiologists evaluate a spread of the disease.
It is important to present students with real-world data for them to analyze. Many government organizations like the Centers for Disease Control and Prevention (CDC) make some of the data they collect available to the public free of charge. This lesson, day 2, and day 3 of the flu tracking lessons show several methods to help students analyze large data sets. Here is an overview of what students will learn today.
Have the students watch the following video clip from NDEP. (I use this video clip with my classes because it describes to the students from where the influenza data that they are about to explore came. Understanding the methods the scientists use to determine the strain of the flu gets students interested in the data and gives them the necessary background they need to understand how the data was collected.)
Ask the students if they have ever been tested for the flu before? If any have, ask them to describe what happened. Explain the procedure that doctors' offices, clinics, and emergency rooms follow for patients who might think they have the flu. (Note: A person who think they might have the flu goes to his or her doctor because they are showing classic flu symptoms which may include high fever, malaise, and achy joint and muscles. The doctor will do a nose swab which can be tested in the office for the particular flu strain. In my experience, I have found that most students know someone who has had the flu even if they haven't had the flu themselves. Also, many of them will know what occurs when a person is tested for influenza. They will not necessarily know what occurs to their sample after the doctors tests them.)
Remind students that the sample collected in the doctor's office will also be sent to a government lab where it is undergoes tests type of viral strain, molecular analysis, and tissue analysis as outlined in the NDEP video. Medical clinics report to county health agencies and the Health Department of their state. The State Health Department reports to the CDC. At the CDC, data is analyzed the determine the extent to the spread of the virus. The CDC shares this data will the public in a flu summary report. Because of the lag time in reporting and analyzing data, the data is always from the previous two weeks. (Note: I have found that it is this portion of where their sample goes that many students will have no knowledge. Most of them will also be unaware that the CDC uses this data to determine the strain in next year's flu vaccine.)
Show students the CDC flu website. Then explain that before they look at this year's data, they are going to look at the data from the previous flu season.
Working as individuals, students should read the narrative on the front page of the flu monitoring worksheet and highlight the main ideas using four different colors. For this assignment, four different highlighters are used to show the four key points of the reading. (I use this method whenever I assign a reading.) Students skim the reading first. Once they have completed the initial first read, they should decide on a main idea of each paragraph and list it in the right hand margin. Next, they should read through the section more carefully highlighting the thesis statement of each paragraph and the supporting details with a highlighter of their choosing. Here is an example of student work demonstrating this method.
Students should consider each graph and respond to the questions concerning the graph. Graph one shows data concerning deaths from the flu and complications due to the flu from years 2008 until 2012. The epidemic threshold and seasonal baseline are indicated. Graph two shows the number of deaths of infants and children from 2009 to 2013. Students should take special note of the 2012-2013 as it shows deaths reported from current week and reported from the previous week. It would also be important to explain to students that the CDC reports time data by year and week. For example, the last week of this year would be 2014-52. The final graph shows the weekly flu data disaggregated by flu strain. The y axis is a two-sided graph. You may need to explain to students how to read the graph. It is also important to have them understand how the right y-axis is calculated. The formula used would be % positive= (number of positive samples/total number of samples)*100%.
(Note: It is important to have students view and interpret sample graph before they use the interactive. Scaffolding in this way keeps the students from becoming overwhelmed by all of the tools of the interactive, the massive amount of data available, and the unique way some of the data is presented in the graphs. Today I just focus on how scientists present their data.)
Refer students to the final graph on the flu monitoring worksheet. Using the formula % positive= (number of positive samples/total number of samples)*100%, solve for the total number of samples for several weeks. Have students calculate the total number of samples submitted to the CDC for one or two weeks so they can appreciate how many samples the government labs process in a week. (Note: I like to have them calculate total number of samples for the height of flu season--201252 and the beginning of flu season--201240.)
Have students consider the following questions and discuss the importance of monitoring the spread of the flu within our country.
- Why is it important to know how much of each strain is infecting people?
- How will this help scientists in planning the vaccine for the next flu season?
Now have students consider the first graph and the difference between seasonal baseline and epidemic threshold. Ask student the following questions:
- What percent of all deaths due to pneumonia and influenza in the country is above the epidemic threshhold?
- What is the normal range of deaths due to pneumonia and influenza in any given week in the country?
- Why is this important to monitor this trend?
(Note: I find that it is very important to introduce students to the types of graphs that they could view before we manipulate the data using FluView Interactive. By choosing a sample of several graphs that student might see, I can guide them in focusing on what epidemiologists find important. To find out more about how I support my students in analyzing data, check out my reflection.)
Putting it All Together
Students should give an one sentence summary that explains the steps doctors and scientists take to control the spread of the flu. (I have students record their responses in their lab notebook which they leave in the room at the end of the hour.) Before the next class period, read the student responses to check for understanding.