According to the medical journals, the symptoms of Swayback disease include weakened arteries, internal bleeding and the laying of abnormally shaped eggs. Coincidentally, these are also three symptoms of being exposed to Denver power trio The Swayback. The group, playing Tuesday, July 15, at the Bluebird, with the Raveonettes and the Warlocks, makes music as infectious as biological warfare. Guitarist Bill Murphy and singer/bassist Eric Halborg inject a thick serum of sludgy punk into your bloodstream, mixing up a dark yet catchy plasma that sounds like the Misfits with a heavy transfusion of Cream. Drummer Forrest Bartosh -- a veteran rock practitioner who has played with Pinhead Circus, the Gamits and the Ladonnas -- then swabs your ass with alcohol and yanks your pants back up. Through it all, Halborg wrings his lungs out into a hacking croon that makes SARS seem about as lethal as the boogie-woogie flu. The Swayback was one of 26 bands chosen from hundreds to appear on Underground Screams, a compilation of unsigned punk bands recently released on the California indie imprint Asian Man Records. In April, the group went to Chicago to record at the eminent Gravity Studio with producer Doug McBride, who has worked with everyone from U.S. Maple to the Jesus Lizard. Still shopping for a label to release the recording, the Swayback continues to be best experienced live; unless you're under quarantine, come down to this show for an inoculation of contagious, platelet-shattering energy and noise. The prognosis is rock.