U.S. researchers found norovirus -- stomach flu -- RNA detectable in groundwater for more than 18 months.

To better understand the risks of waterborne norovirus transmission, researchers at Emory University's Center for Global Safe Water examined how long norovirus remains infectious in water.

Common symptoms of norovirus gastroenteritis include diarrhea, vomiting and stomach cramping.

Noroviruses are highly contagious and easily spread through several different ways such as eating foods or drinking liquid contaminated with a norovirus. Treatment for norovirus gastroenteritis consists of managing the symptoms while the body fights off the infection.

Outbreaks of norovirus are associated with contaminated groundwater, surface water and recreational water and causes serious morbidity and economic losses.

The researchers presented the finding at the American Public Health Association's annual meeting in Philadelphia.