The Hawaii Department of Health said Wednesday that it is investigating two cases of Legionnaires’ disease in guests who stayed at The Grand Islander by Hilton Grand Vacations in Waikiki.

DOH said it is aware of two confirmed cases of Legionnaires’ disease — both visitors — who were diagnosed following a stay at The Grand Islander. The first case was diagnosed in June 2021, and the second case on March 6 or 7.

“While the risk to the general public is low, cases of Legionnaires’ disease are on the rise nationwide,” said State Epidemiologist Dr. Sarah Kemble in a news release. “Individuals who stayed at the Hilton Grand Islander in the last two weeks who develop symptoms or individuals who were diagnosed with Legionnaires’ disease after a stay at the Grand Islander are encouraged to seek medical attention and contact DOH.”

A statement from a Hilton Grands Vacation spokesperson, issued Thursday, said, “The Hawaii Department of Health informed Hilton Grand Vacations that an individual who recently visited Honolulu was diagnosed with Legionella upon returning home.

“This individual stayed at The Grand Islander, a Hilton Grand Vacations Club. Our team is following all guidance from the Hawaii Department of Health and Centers for Disease Control and Prevention as a thorough investigation is conducted. The health and safety of our owners, guests and team members is our top priority. While the investigation is ongoing and it is not yet known how or where this individual was infected, out of an abundance of caution, we are taking several steps to ensure everyone’s safety, including temperature treating of systems, which was completed March 23. This non-chemical process is not harmful and only involves increasing water temperatures to systems at The Grand Islander.”

Legionnaires’ disease is a serious type of pneumonia caused by exposure to Legionella bacteria, which are found in freshwater environments, according to DOH, and can spread via water systems such as showerheads, sink faucets, cooling towers, hot tubs, and large plumbing systems.

Symptoms include cough, shortness of breath, fever, muscle aches, and headache, and usually begin within two to 14 days of exposure.

Most healthy people exposed to Legionella bacteria do not develop Legionnaires’ disease, but those ages 50 and older, current or former smokers, and people with a chronic lung disease or weakened immune system are at increased risk.

The disease is treated with antibiotics, and in general, people do not spread it to others, according to the U.S. Centers for Disease Control and Prevention.

DOH said it is still investigating the exact source of the illness and extent of spread, and that it is working closely with the Grand Islander, which has been cooperative.

Public health agencies across the country have also been asked to report cases of Legionnaires’ disease with a travel history to Hawaii.

To report a case, call 808-586-4586 to reach DOH’s Disease Outbreak and Control Division Disease Reporting Line or visit health.hawaii.gov/docd contact-us to report it online.

This story was updated Thursday to include a statement from a Hilton Grands Vacation spokesperson.