As a class, we are going to act out the scenario below, with students taking the parts of the Narrator, Nancy, Dr. Ghee, and Elaine (Dr. Ghee’s nurse).
- Narrator:
- It is July, and it’s sweltering in St. Louis, Missouri. A young woman named Nancy waits nervously in the examining room of a local doctor. There’s air conditioning here, but the woman does not look very comfortable. She sighs repeatedly and rubs her neck from time to time. After a brief wait, Elaine, the nurse, enters and takes Nancy’s vital signs and updates her chart.
- Elaine:
- Well, your weight is down a few pounds from your last visit—124 pounds—and it was 128 in, let me see …, October. It’s nothing to worry about of course; 124 pounds is an excellent weight for a young woman your height. Let’s see, you’re what …, about 21 years old?
- Nancy:
- I’m 25.
- Elaine:
- Oh, right, of course. Your pulse is normal. Your blood pressure is a little low, but it’s within the normal range. You do have a fever though—101.5. How do you feel?
- Nancy:
- I feel awful. I have a headache, and I ache all over.
- Elaine:
- Any nausea?
- Nancy:
- No, not really. But I sure don’t feel like eating. I guess that’s why I’ve lost a few pounds. I just feel lousy. But I mean really lousy. It’s a couple of days now. I don’t get it—it’s not flu season, and I had a shot, anyway.
- Elaine:
- Let’s see what the doctor says. She’ll be right in.
- Narrator:
- After a short wait, the doctor arrives and the following conversation ensues.
- Dr. Ghee:
- Hi, Nancy. I haven’t seen you for a while. What seems to be the problem today?
- Nancy:
- Well, I got my flu shot last October. All of us got them. But it feels like I have the flu. I have no appetite. I have killer headaches and everything hurts, even my bones! If I stop taking acetaminophen, I get a fever. It’s been a few days now.
- Dr. Ghee:
- When you say “all of us,” who do you mean …?
- Nancy:
- All of the nurses on my unit got flu shots—it’s required.
- Dr. Ghee:
- Oh, right. You look so young I always think you’re still in college. It seems like you were shadowing in this office only last year. But that can’t be right. I guess you’re a nurse now, right? So, what do you think may be going on?
- Narrator:
- Nancy hesitates for a moment.
- Nancy:
- Dr. Ghee, I had a needlestick incident a week or so ago. It was minor, and the patient was HIV negative and she didn’t have hepatitis. I didn’t think much of it, just cleaned the wound and filled out a report.
- Narrator:
- Doctor Ghee looks grave.
- Dr. Ghee:
- Do you know what the patient was hospitalized for, Nancy?
- Nancy:
- She had picked up a case of dengue on vacation abroad. You can’t get dengue from a needlestick, can you?
- Dr. Ghee:
- Well, it’s possible, although I’ve never heard of it before. Let’s take a more thorough look at you and do some blood work.
Questions
How does this story highlight the importance of taking a thorough medical and personal history of a patient? What sorts of questions are important to ask someone who is ill?
Why does the doctor want to take a “closer look” at Nancy? What sort of things might she look for?
What exactly does “blood work” mean? What kind of tests is the doctor likely to order using the blood and why? What about the urine and/or sputum sample?
Now look over the Figure and Table from the article you read; be sure you understand them and try to interpret the results. The questions below are intended to guide your understanding of this material.
Further Questions
What is a leukocyte? Are leukocytes raised or depleted in Nancy’s blood? What is the usual significance of an elevated leukocyte count? What’s going on with the lymphocytes?
An EIA (enzyme-linked-immunosorbent assay, sometimes also called an ELISA) is a frequently used technique that allows medical personnel and researchers to identify and quantitate proteins such as antibodies, antigens, or other immune system chemicals that are present in biological fluids. Antibodies are proteins produced by white blood cells called B cells. They bind in a highly specific “lock and key” fashion to viruses, bacteria, fungi, and to pieces of viruses, bacteria, and fungi. The immune system uses these antibodies almost like handles that aid in clearance of the infecting organisms as well as to tag pathogens and identify them as foreign, which also facilitates clearance and healing. There are several different classes of antibody (or immunoglobulin, as the antibody protein is properly named), including IgM, IgG, IgD, IgA and IgE. IgM is always present on the surface of resting B cells, and is the first class of antibody secreted (released into the fluid portion of the blood) in response to infection. After the immune response matures a bit, with the help of T lymphocytes, the predominant antibody class present switches to IgG. In people who have been previously exposed to a pathogen, memory B cells exist, and these express IgG bound to their cell membranes. Upon stimulation by re-infection, they differentiate into plasma cells that secrete IgG that is directed against the pathogen. In the second set of results, EIA was used to quantify anti-dengue antibodies in Nancy’s blood. What do the results tell you? What new, complementary information is gained from the EIA report?
What is the significance of the RT-PCR results?
What actions will Dr. Ghee take in treating Nancy?
Note: You may have some trouble answering Question 4. It’s hard to give advice if you don’t have enough background information to make rational decisions. Please list some of the questions that you have about dengue and the related condition known as dengue hemorrhagic fever (DHF). Also list any questions you may have about the techniques or tests used in the journal article.
Homework Assignment
Dr. Ghee also did not know a lot about dengue because it is a disease not often encountered in American doctors’ offices. She went to the Centers for Disease Control (CDC) website and read about the history, immunology, treatment, etc., for dengue. You will also be using this site as a point of departure to prepare PowerPoint presentations answering some of the questions you have generated above.
We will divide up into groups. Each group will use information gained from the Resources in Part I to generate a short PowerPoint presentation on a chosen/assigned topic from the list of questions generated. These will be presented at the next class meeting, and eventually posted on the class website. Each group’s presentation will be graded according to the Presentation Grading Rubric.
In addition, in order to receive credit for this assignment, the group must prepare a one-page summary hand-out for the class and also post the PowerPoint presentation on the class website.
Originally published at http://www.sciencecases.org/dengue/dengue1.asp
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