You know that disease that's been killing piglets and driving up pork prices? Well, it's been on a sort of summer vacation. But experts say it will roar back come autumn, so get ready to pay more for bacon. U.S. veterinarians say the disease -- Porcine Epidemic Diarrhea virus (PEDv) -- will likely kill another 2.5 million pigs over the next 12 months. PEDv thrives in cold, damp conditions and the spread has slowed, after peaking in February, as the temperature has warmed up. It has already killed about 8 million pigs, about 10 percent of the U.S. herd, and helped boost pork prices to $4.10 a pound, an all time high. Prices could reach $4.64 by December, said Ricky Volpe, an economist for the USDA. "There is still plenty of disease out there and it will be back with a vengeance in the fall," said Eric Neumann, a veterinarian studying the transmission of PEDv.