An investigation continues into what has caused hundreds of visitors to a Tennessee zip line destination to suddenly develop a gastrointestinal illness. More than 500 people have reported symptoms including stomachache, nausea and vomiting after visiting the CLIMB Works Zipline Canopy Tour in Gatlinburg. The Tennessee Department of Health announced Thursday that officials are continuing to look for the cause of the illnesses. “At this time, we cannot point to one simple cause of this outbreak,” John Dunn, the department’s deputy state epidemiologist, said in the news release about the investigation. Since June, several visitors to the CLIMB Works facility tested positive...