The state is urging medical professionals to be on the look out after confirming a second measles case in Wahiawa.
"Unfortunately, we now have a secondary case and because of that secondary case more have been potentially exposed," said Dr. Sarah Park, state epidemiologist.
The latest victim is a two-year-old who came into contact the first measles patient at an undisclosed Oahu pediatrician's office.
Both children were treated at Wahiawa General Hospital.
"This is toddler ... subsequently developed classic signs of measles about a week an a half after the exposure," Park said.
The first victim -- who has since recovered -- recently traveled to the Philippines and Guam.
"The second one for now seems to be stable at home," Park said.
State officials are now notifying others who may have been exposed.
They're also asking medical professionals in the Wahiawa area to give a heads up when they refer suspected measles cases their way.
Measles are much more contagious that the flu and victims can develop complications such as pneumonia. In the U.S., about one in every 500 cases ends up in death.