An ancient virus that is a cousin of HIV is infecting a large portion of indigenous people in Australia, and doctors are unsure how it got to be so prevalent. HTLV-1, or Human T-lymphotropic virus 1, is a human retrovirus that can cause harmful diseases such as bronchitis, leukemia, and lymphoma. Researchers have found traces of the virus in 1500-year-old Andean mummies. A recent preliminary study from the Baker Institute for Heart and Diabetes in Alice Springs found that 40 percent of adults living in a remote region in Australia are infected with HTLV-1. Less than 14 percent of the...