At one point during the French Chateau chapter, Nate & Sully come across a body of one of Talbot's men that is heavily decayed. Sully questions how it was possible for the body to be so decayed as Talbot and his men "just got there".
While I was hoping this would be explained as the game went on, no references were ever made back to it.
Best Answer
According to the Uncharted Wiki, Talbot's man was killed by the spiders. As there is no direct reference to the cause of death in the game, I think you're just supposed to infer it.