Washington Post: It started with a slightly puffy eyelid in early summer, which I waved off as an inconsequential bug bite. The next morning, I couldn’t ignore my son’s symptoms when he appeared with two eyes swollen to slits, a bloated face and an itchy rash raging over his body. Ah, poison ivy. How it torments with weepy rashes and maddening itchiness — and may do so more and more. That is what the experts say, and I can offer supporting testimony, at least for this season’s crop. “It …