Officials said the risk to the public is low. The child did not have contacts with a school or daycare.
"The limited number of patients and families who were believed to have had contact with this patient during this patient's infectious period are being contacted and provided with instructions on steps to help prevent any spread," the Rhode Island Department of Health said in a statement late on Friday.
The health department is consulting with the Centers for Disease Control and Prevention on other measures, including treating any unvaccinated individuals with prophylaxis who might have been exposed.
Measles, a "highly contagious" respiratory infection caused by a virus, spreads to others through close contact and when an infected person coughs or sneezes. A room visited by someone with the illness can be infectious for up to two hours, health officials said, citing the CDC.
But officials added that the vaccine for measles, mumps, and rubella (MMR), typically given to children between the ages of 12 to 15 months and then at 4 to 6 years old, offers strong protection against the illness. About 97 percent of Rhode Island kindergartners have been vaccinated with the MMR doses, a "very good" rate, they said.
"Measles is almost entirely preventable through vaccination," Jerry Larkin, the director for the state's health department, said in a statement. "Any parent or guardian who has a child at home who is older than a year old and has not been vaccinated against measles should talk to their child's healthcare professional."
Measles was officially eradicated from the United States about 25 years ago through a vaccination campaign, according to the CDC. This means that the infection stopped spreading within the country, and new cases are among individuals who caught the infection after traveling abroad.
When more than 95 percent of people in a community have been vaccinated, they achieve what the CDC describes as herd immunity protection.
In recent years, however, national rates of vaccinations for measles have declined.
During the 2023-24 school year, only about 93 percent of American kindergartners had been given the full MMR doses, down from over 95 percent in 2019-2020, according to the CDC. This left about 280,000 children without the protection against measles that the MMR vaccination affords.
In addition to Rhode Island's 97 percent vaccination rate, other New England states also have higher rates of MMR vaccination compared to the national level. In Massachusetts, a little over 96 percent of kindergartners are vaccinated; in Connecticut, the rate is close to 98 percent, while Maine recorded a vaccination rate of 97.5 percent, data from the CDC shows.