The Dengue Dilemma
Dengue provides an excellent opportunity to illustrate the interaction between humans and the environment, the impact those actions can have on the health of an entire community, as well as the medical mystery of dengue and the immune response to the different serotypes. Looking at translational research, there is much work devoted to developing a vaccine, with clinical trials underway evaluating the efficacy and safety of different formulations. Always trying to minimize harm, is it possible to vaccinate against dengue without then putting a vaccinated person at risk for subsequent infection and increased immune response?
In the introduction to The Dengue Dilemma you will find tips on using the curriculum, summaries of each lesson, a lesson sequencing guide, pertinent vocabulary, a standards alignment chart (Next Generation Sunshine State Standards), and general background information for the unit.
Students will use the first case report from the Key West 2009 dengue outbreak to complete an epidemiological report. This lesson begins with a patient’s initial symptoms and visit to her primary care physician. After a return trip and visit to the emergency room, initial testing for dengue will be conducted by the students in the next lesson.
Student match diagrams with text descriptions to understand the steps of an ELISA. A common test used to detect if a patient has been exposed to dengue virus is called an ELISA (enzyme linked immunosorbant assay). This test takes advantage of the interactions between antigens and antibodies. Often compared to a lock and key, an antigen/antibody interaction is very specific.
Using a commercial classroom-friendly ELISA kit, students will test the patient serum sample for the presence of dengue antibodies, and record their results on the epidemiological report. A simulated version is also presented.
Using simulated PCR products, students will perform gel electrophoresis to determine which serotype of dengue virus our patient is infected with. They will have positive controls for all four serotypes and compare them with the patient’s cerebral spinal fluid sample taken early in the course of her infection. The students will determine that our patient is positive for serotype 1 (DENV1) and record this information on their epidemiological report.
Different assays are used to test for and diagnose dengue virus. The two main tests utilized are the ELISA and RT-PCR. Students have now learned about each of these assays and should consider why each test was performed depending on the sample and date taken. Using the host response graph, students will answer questions to help clarify their thinking and then apply this knowledge to patient case #1.