A new study published in The Lancet Infectious Diseases, shows a need for a vaccine to prevent the often violent attacks of vomiting and diarrhea associated with Norovirus, researchers said.

“Our findings show that norovirus infection contributes substantially to the global burden of acute gastroenteritis, causing both severe and mild cases and across all age groups,” said study author Dr. Benjamin Lopman, from the U.S. Centers for Disease Control and Prevention.

“The virus is so contagious that as few as 18 viral particles may be enough to infect a healthy person, while more than a billion viruses can be found in a single gram of an infected person’s stool,” Lopman said.

Currently, there is no treatment for norovirus.

For the study, researchers analyzed data from more than 187,000 cases of acute gastroenteritis in 48 countries between 1990 and 2014. They found that norovirus was responsible for 18 percent of those cases.

Norovirus was more likely to cause gastroenteritis in the community (24 percent) and among people receiving outpatient care (20 percent) than among emergency department and hospital patients (17 percent).

The researchers also found that rates of gastroenteritis caused by norovirus were similar in developed (20 percent) and developing countries (14 to 19 percent). This suggests that unlike harmful bacteria and parasites, norovirus can’t be controlled just by improving water quality and sanitation, the study authors said.