They're probably the most important diseases you've never heard of -- causing everything from greusome limb disfigurement and skin sores to bladder and liver cancers to neurological damage -- and they're practically ubiquitous among world's poorest people. Typically, such infections last for years or even decades, causing chronic and permanent disabilities such as stunted growth and intellectual developments in children; blindness, heart disease, and disfigurement of adults; and pregnancy complications that can result in severe disease in both newborns and their mothers.