Question

On a sunny, lazy July afternoon at the family lakeside cabin, 10 year old Ethan is tossing a slobbery tennis ball to Daisy, the family’s dog. The dog bounds into the underbrush to retrieve an arrant throw. When the game is over, Ethan wraps his arms around Daisy and hugs her. A week later, Ethan wakes up his mother, Maureen, complaining that he itches. The right side of his face is red and covered with small bumps. Convinced that Ethan is just suffering from bug bites, Maureen gives him an antihistamine to relieve the itching. By morning, though, Ethan is worse- the red angry rash has spread to his neck and arms, his face is swollen, and blisters appear. Maureen applies an over the counter anti- itch cream and tells Ethan not to touch the blisters, but he can’t help scratching them. Three days after that, Ethan still feels and looks miserable, and Maureen is really getting worried. Then she notices pus oozing from his blisters. Panicking, she immediately drives Ethan to the doctor’s office. As soon as the doctor sees Ethan, she says, “ Looks like you had a run in with poison ivy. She prescribes a glucocorticoid ointment for applying to the skin rash and recommends continuing the antihistamine to control the agonizing itch.


Q1. What is wrong with Ethan? Did bitting bug cause Ethan’s discomfort?






Q2. Daisy went into the woods not Ethan, then why Ethan showed allergic symptoms of poison ivy? Explain in detail?









Q3. Do you think if there is role of T- cells n Ethan’s condition? Why?






Q4.Why is the inflammatory response to poison ivy( Urushiol/ poison ivy sap) delayed for at least 12 to 48 hours after exposure?













Q5. What precautions should Ethan would take to avoid inflammatory response?

Answer 1

1. Ethan is infected with poison ivy. Bug bite didn’t cause this. It is transmitted from his pet dog which was exposed to the poison from the Bush.
2. The rash is caused by direct or indirect contact. Indirect contact is from plant oil that has contaminated pet fur, tools, clothing or other surfaces. Since his pet went into the woods it got contaminated with the plant oil and when Ethan wrapped his arms around Daisy it got transmitted to him.
3. Poison ivy causes allergic contact dermatitis. It is a T cell mediated immune response. It is also called as delayed hypersensitivity.
4. The T lymphocytes recognise the poison as foreign substance after the antigens are eaten and degraded into pieces. The lymphocytes signals for the inflammatory substances called cytokines. This activates the macrophages and attack causing severe tissue damage.
5. The precautions to be taken are cover skin while playing, avoid exposure to pets, don't allow pets into the woods, bath the pets often, use protective devices if exposed to the plants.