Answer: A synonym for virulent is toxic, poisonous, harmful, etc.
For the personal story, you could say…
My family decided to take me on a road trip to the desert as a way of spending more time together as a family. Due to the heat, we brought many items, including water, sunglasses, an umbrella, etc. My mom also brought some board games that we could play to kill time. We had been playing for hours and hours when I suddenly felt a sharp, throbbing, and burning pain in my leg. I yelled out in pain, and my parents came running over to me to see what was wrong. My leg had bite marks and was a bit swollen. In the end, it turns out I was bitten by a snake, but it wasn't anything too serious, and I should be fine in a couple of days.
Explanation: I hope that this helped you in any way! Also, if it didn't, please don't hate me!!!!!!