Although nearly universally regarded as one of the greatest recent disasters in our hemisphere, the 2010 Haiti earthquake didn’t take long to fall out of the headlines. But a million people there are still homeless, and there’s a rampant cholera outbreak. Solving the latter problem is simply a matter of providing uncontaminated water, a task being tackled by Kentucky-based Christian charity Edge Outreach, the beneficiary of Bonnie “Prince” Billy & The Cairo Gang’s new single, Island Brothers / New Wonder. Continuing the textured folk sound of last year’s critically acclaimed Wonder Show Of The World, the two previously unreleased songs were culled from live sets and are packed with photos from Haiti taken by New York Times photographer Damon Winter. “Island Brothers” is unquestionably the main draw here: A blend of spirited guitar riffs, old-time piano, soulful vocal harmonies, Will Oldham’s airy warble, and a touch of reverb, the song lightly wanders from country-rock to a drowsy, horn-infused conclusion, with special guest Rob Mazurek adding a gently psychedelic, jazzy solo. “New Wonder” is a fragile, slow ballad, drifting with atmospheric piano-fluttering and the lullaby harmony of “Change, we will change.” Both songs make a subdued plea for attention, and there’s no doubt this cause deserves it.