An unvaccinated French boy is suspected of bringing measles back to Costa Rica, a country which had been free of the disease for five years.

The 5-year-old boy arrived with his parents for vacation on Feb. 18, Costa Rica’s Ministry of Health said in a statement.

The child’s mother, who was also not vaccinated, consulted a private doctor about his rash and confirmed that other children in his school had contracted measles, the Costa Rica Star reported.

Measles is an extremely contagious illness caused by a virus that is spread through the air.

The boy was then quarantined at the hospital, the Ministry of Health said, and authorities began contacting people he may have exposed to the virus both in Costa Rica and in France.

Costa Rica has not had a domestic case of measles since 2006, and the last imported case occurred in 2014.

The measles two-dose vaccine is 97 percent effective against the virus, according to the CDC, but the number of children who aren’t being vaccinated by 24 months old has been gradually increasing.

People choosing not to vaccinate have become a global health threat in 2019, the World Health Organization reported.

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Contributing: Ashley May and Brett Molina, USA TODAY

Follow N'dea Yancey-Bragg on Twitter: @NdeaYanceyBragg