Meet the new rage among HIVer gay men in Europe: lymphogranuloma venereum, or LGV, a rare STD caused by some strains of the common bacterial pest chlamydia. It arrives with an often-unnoticed, painless genital sore. Two to six weeks later, the real fun starts, when lymph nodes in the groin swell and smart. Antibiotics like doxycycline or erythromycin kick butt—but without ’em, your butt (rectum and colon) could also swell and suffer. LGV hasn’t hit the U.S. in large numbers, but docs are being warned so they’ll know it when they see it. And now you will, too.