The Question and Answer section for The Hot Zone is a great resource to ask questions, find answers, and discuss the novel.
I cannot promise the accuracy of my answer without knowing which chapter your question pertains to, but Jahrling takes samples of his own blood to run tests.
If you have a specific chapter number, please include it below.
I'm sorry, what point? What section of the novel are you referring to?
McCormick was hopelessly ill equipped to take blood samples when he entered a hut filled with Ebola victims. He was sure he would contract it.