Half the world\'s adults -- 2.3 billion people -- will have urinary tract symptoms by 2018, an increase of 18 percent in 10 years, a U.S. researchers says. Lead author Dr. Debra E. Irwin of the University of North Carolina said nearly half of all adults age 20 and older will experience at least one lower urinary tract symptom by 2018. Issues such as incontinence will also increase as people age in South America, Asia and the developing regions of Africa. \"Our study suggests that urinary and bladder symptoms are already highly prevalent worldwide and that these rates will increase significantly as the population ages,\" Irwin said in a statement. \"These findings raise a number of important worldwide issues that will need to be tackled, as a matter of urgency, by clinicians and public health experts if we are to prevent, and manage, these conditions.\" The study, published in the urology journal BJUI, found at least one lower urinary track symptom will affect an estimated 2.3 billion people between 2008 and 2018 -- with the biggest increase in Africa at 30 percent, followed by South America at 20.5 percent, Asia at 20 percent, North America at 16 percent and Europe at 2.5 percent.