You SHOULD worry. Despite the best medical treatment, I knew someone who died from malaria he got in Kenya.
I do, too. It was a guy who had just retired from the hardware business, and a father of a grade school and middle school classmate of my daughter. He came home, got sick, rebounded, crashed and died a few weeks later. The community was in shock. That's why I'm worried about her.
If I remember correctly, he was given an anti-maliarial drug that had been superceded by a newer, more effective medication. I hope she and the rest of the group are taking the most up-to-date drugs available. I'll worry until she gets back. And she's probably having the time of her life.