Travelers afflicted with HIV
Travelers to the United States who are HIV-positive are not eligible, under current United States visa law, to travel visa free under the Visa Waiver Program. They are required to apply for a visa (http://www.usembassy.org.uk/cons_new/visa/niv/add_hiv.html) and a waiver of the ineligibility before traveling.
Hope that helps! :)
Patrick