Survivor creator Mark Burnett encountered some problems of the viral variety on the set of his upcoming USA Network series, Eco-challenge, according to Broadcasting & Cable. Some of the 312 contestants participating in the six-day Borneo adventure came down with leptospirosis, which suppresses the immune system and can cause high fevers. Turns out the infected contestants picked up the icky virus while swimming in a contaminated river. "Everyone is just fine now," assures an exec at Burnett's L.A. studio. Eco-challenge is set to debut in April.