The Hawaii Department of Health today said laboratory results confirmed norovirus to be the cause of multiple illnesses reported by campers at Kalalau Valley on Kauai.

The Hawaii Department of Land and Natural Resources closed Kalalau Valley at the Napali Coast State Wilderness Park on Kauai on Wednesday upon DOH’s recommendation due to an outbreak of suspected norovirus.

The trail and campgrounds are expected to remain closed for seven days.

Since Aug. 14, DOH has received 24 reports of acute gastrointestinal illness, with symptoms such as nausea, vomiting and diarrhea from people who have hiked the Kalalau Trail.

Over the weekend, Kauai County firefighters responded to multiple calls for rescue at Kalalau from hikers who became ill on the trail, and airlifted one out of the area via helicopter.

The 32-year-old womaon reported becoming sick after drinking water from the area, according to the Kauai Fire Department, and was taken by medics to Kauai Veterans Memorial Hospital in stable condition.

The state Health Department said four patients were tested, and all tested positive for norovirus and have been notified of the results.

The department is working with DLNR to conduct environmental sampling at the campgrounds and surrounding areas.

Norovirus is a very contagious virus that causes vomiting and diarrhea, according to U.S. Centers for Disease Control and Prevention.

People can become infected with a norovirus through direct contact with someone with the virus, by eating or drinking contaminated food or water or by touching contaminated surfaces and then their mouths.

Norovirus can also be found in shellfish, particularly oysters and clams.

Symptoms, which usually begin about 24 to 48 hours after exposure, include nausea, vomiting, diarrhea and stomach cramps — and sometimes fever, headache, and body aches.

Most people with norovirus illness get better within one to three days, according to CDC, but can still spread the virus a few days after.

DLNR said individuals who recently hiked the trail should monitor themselves for symptoms. If symptoms are severe, or do not resolve within one to two days, people should seek medical care promptly.

Permit holders for the closed dates at Kalalau can request a refund or rebook to a later date by emailing DLNR.DSP.Permits@hawaii.gov.

To report an illness, contact the DOH Disease Investigation Branch on Oahu at 808-586-4586.