Officials confirmed that of the 32 RNC organizers staying at the Kalahari resort in Ohio, at least 10 have symptoms of norovirus.
According to the U.S. Centers for Disease Control and Prevention (CDC), norovirus causes inflammation of the stomach, intestines or both. The virus is known for spreading rapidly through a large group of people.
Symptoms of norovirus include vomiting, diarrhea, and nausea. Some people may have low-grade fever or headaches.
"If you have norovirus illness, you can feel extremely ill and throw up or have diarrhea many times a day," the CDC website states. "This can lead to dehydration, especially in young children, older adults, and people with other illnesses."
Two pregnant women who exhibited symptoms went to a local hospital for care. Others who are infected have been told to remain in their hospital rooms.
Samples have been sent to a lab to confirm the illness is norovirus. Health officials told ABC News they believe that the people were infected in California before they arrived in Ohio.
Five of six people who originally had symptoms were on the same flight and the roommates of the first six people infected were the next to show symptoms.
The virus can be hard to stop since it can stay on objects and surfaces for weeks. Every year an estimated 19 to 21 million people are infected with norovirus in the U.S. every year, according to the CDC.