The state Health Department today says it has confirmed five cases of whooping cough, or pertussis, among members of one household visiting Hawaii from the U.S. mainland.

One child from the household was hospitalized, and all five cases were unvaccinated, according to the Hawaii Department of Health.

The family stayed at a hotel on Oahu.

“DOH is coordinating with the Centers for Disease Control and Prevention and other states to notify travelers who were exposed,” said the department in a news release. “DOH investigation has identified no close contacts after the family’s arrival in Hawaii.”

Pertussis is a highly contagious respiratory illness caused by bacteria, according to the CDC, which can spread easily from person to person through the air.

In its early stages, pertussis may begin like a common cold, but can cause severe coughing fits in later stages that last up to 10 weeks or more.

The coughing fits can cause a high-pitched “whoop” sound when breathing in.

Whooping cough can lead to serious complications, especially in infants — but infants may not cough at all, DOH said. Instead, they may turn blue or struggle to breathe.

From 2019 to 2023, DOH said, there have been 89 confirmed and probable pertussis cases reported in Hawaii, including 28 that were linked to three outbreaks.

The last confirmed case of pertussis in the state occurred last March.

“The best way to protect you and your loved ones is to stay up to date with recommended whooping cough vaccines,” said DOH in the release. “Two vaccines used in the U.S. help prevent whooping cough: DTaP and Tdap.”

Children younger than 7 years old get DTaP, while older children, teens, and adults get Tdap, DOH said, and those who are pregnant should get a Tdap vaccine during the third trimester to help protect their baby early in life.

The department advises seeing a doctor as soon as possible if you or your child are experiencing symptoms such as runny nose, fever and violent and rapid coughs, struggle breathing, or turning blue or purple.