LAS VEGAS (AP) -- A year after hundreds of Las Vegas Rock 'n' Roll Marathon and Half-Marathon runners reported symptoms of stomach illness, organizers on Monday promised changes that include strict sanitation rules and the hiring of a contractor to supply water to runners.
Revisions for Sunday's event include the use of closed 125-gallon tanks with spigot hoses at water stations along the courses, officials said. Water will be trucked in, instead of drawn from fire hydrants.
"Water will not be exposed like it was previously. We're going to take the extra step," said Adam Zocks, event director for the San Diego-based Competitor Group Inc.
The water supply contractor, Rick Margiotta, of Austin, Texas, said he has supplied water using the tank system at Rock 'n' Roll marathons in New Orleans and Washington, D.C.
Last year, gloveless volunteers handed out cups to 44,000 runners at water stations along the course. The water and a sports drink were scooped from open-top barrels that had plastic sanitary liners.
The Southern Nevada Health District never conclusively identified the source of 528 cases of Sapovirus gastroenteritis. After a couple of days of discomfort, everyone recovered.
Those who reported diarrhea and vomiting common to the illness were most likely exposed at a health and fitness expo where race numbers were distributed the morning of the race, district epidemiologist Brian Labus concluded in a March report.
"Exposure during the race was not the cause," Labus said in the 19-page report.
Intestinal distress is also a common ailment for inexperienced marathoners, he noted.
The Sapovirus is named for Sapporo, Japan, where it was first discovered among children in an orphanage in 1977.
Last year's outbreak was the first in the Las Vegas area, according to the health district.
Other changes for this weekend's event include starting each of the races an hour earlier on the Las Vegas Strip and moving the finish line from near the Mandalay Bay resort to the block in front of The Mirage.
About 5,000 runners are registered for the marathon, which begins at 3 p.m. Another 25,000 are registered for the 13.1-mile half-marathon starting at 4:30 p.m.
Participants will come from every U.S. state and more than 30 countries. They'll gather in a runners' village area near the Luxor resort, instead of the Mandalay Bay, and start in stages according to their expected pace and course time to ease congestion.
Marathoners will pass performers on 19 stages -- about 40 music and entertainment groups have been booked for the event, Zocks said. And everyone will finish beneath the neon glow of the resort corridor.
"Every runner across the finish line, from the first one to the last one, should have the same great experience, highlighted by running on the Las Vegas Strip," Zocks said.