During the Naked and Afraid XL finale we learned that Trent Nielsen was suffering from an unknown illness that left him weakened to the point that his teeth were falling out. Concerned for his safety, a medical crew tested his blood and the results weren't so good.
Nielsen was informed by the medic that he tested positive for malaria. Malaria is a mosquito-borne parasitic disease that leaves its victims with severe headaches, fever, nausea, and diarrhea. In fact, hundreds of thousands of people die from malaria every year.
Since Nielsen was already weakened from the challenge, the disease hit him very hard. He was administered the antibiotic doxycycline in hopes of combating the disease, but he refuse to quit the challenge because he was so close the 40th day and extraction.
Nielsen said, "To go through this extraction in the condition that I'm in with the malaria it's going to make it much harder but I want to be with my team all the way to the end."
Despite being weakened by malaria, Nielsen managed to swim crocodile infested waters and hike five miles, earning much respect from his fellow contestants. Contestant Matt Wright said, "Trent is one of those that, he's not going to let a little malaria slow him down."
Nielsen completed the challenge and made a full recovery.