LAS VEGAS (AP) -- After health officials investigated a stomach illness following last year's Las Vegas Rock `n' Roll Marathon and Half-Marathon, organizers are promising several changes to this year's races -- including strict sanitation rules and a contractor supplying water to runners.
The Southern Nevada Health District never conclusively identified the source of Sapovirus outbreak reported by more than 500 of the 44,000 race participants a year ago.
A health district investigation determined that people were probably exposed to the virus the morning before the race -- maybe at a runners' expo where race numbers were distributed.
Water distribution during the race had been suspected.
This year's race is Sunday evening on the Las Vegas Strip, and Competitor Group officials say this year's 30,000-plus participants will notice the changes that have been planned.