Passengers vaccinated against measles aboard a Scientology cruise ship

WILLEMSTAD, CURACAO (AP) – Curaçao authorities boarded a quarantined ship on Saturday to begin vaccinating the population to prevent a measles outbreak.

Health officials said that only people already vaccinated or having already had measles would be free to leave the ship Freewinds (134 meters), which belongs to the Church of Scientology.

Dr. Izzy Gerstenbluth, an epidemiologist in Curacao, told the Associated Press that a small team was evaluating more than 300 people aboard the ship and that the process could last more than one day.

"We will do our job," he said, adding that the authorities have an international obligation to prevent the spread of the disease. "If we allow this to happen, measles spreads to places where the risk of serious complications is much greater, especially when we are talking about poor countries where people have a lower level of resistance."

Authorities fear that people on board the ship have been exposed as a result of the measles diagnosis to a female crew member after her return from Europe. Gerstenbluth said he arrived on the Caribbean island of Curaçao on April 17 and visited a doctor on April 22 for cold symptoms. A blood sample was taken and sent to Aruba, where authorities confirmed that it was a measles outbreak on April 29, a day after the ship's departure for St. Lucia. Curaçao's health officials then alerted the authorities in St. Lucia.

The Freewinds was quarantined in St. Lucia earlier this week before returning to its home port of Curacao on Saturday morning.

Gerstenbluth said it would be easy to spread the disease as it was a small ship.

"That's what happens when we do not vaccinate," he said.

Symptoms include runny nose, fever and a rash with red spots. Most people get better, but measles can cause pneumonia, swelling of the brain and even death in some cases.

Measles has sickened more than 700 people in 22 US states this year, federal officials say the resurgence of the disease is caused by misinformation about vaccines.

Church officials did not respond to calls for comment. According to the church's website, the ship is the home of a "religious retreat providing the most advanced level of spiritual counseling". It indicates that religious conventions and seminars also take place on board.