When sanitation systems are available and used, the odds of contracting one of a group of diseases, known as soil-transmitted helminths (STH), is cut in half, according to a systemic review and meta-analysis published this week in PLoS Medicine, Examiner.com reports (Herriman, 1/25). "One billion of the world's people experience a diminished ability to work, learn, and thrive as a result of infection by these parasites -- roundworm, whipworm, and hookworm. The resulting losses in quality of life and productivity can trap people in a cycle of poverty and stigma and diminish their ability to care for themselves and their families," the PLoS "Speaking of Medicine" blog writes.