A cruise ship which acts as a religious retreat for the Church of Scientology has been quarantined in the Caribbean after a person on board was diagnosed with measles.
The Freewinds, a 440ft vessel, was prevented from disembarking by authorities on the island of St.Lucia.
It was believed to have nearly 300 passengers on board, and the infected person was reportedly a female crew member.
Dr Merlene Fredericks-James, the island’s chief medical officer, said: "Because of the risk of potential infection, not just from the confirmed measles case, but from other persons who may be on the boat at the time, we thought it prudent to make a decision not to allow anyone to disembark.
"One infected person can easily infect others. We thought it prudent that we quarantine the ship."
She did not name the vessel but officials with St. Lucia’s Marine Police confirmed it was the Freewinds.
The development came as the United States is facing an outbreak that has led to the highest number of measles cases in 25 years.
More than 700 people have been infected in 22 US states this year.
Health officials have blamed the resurgence on misinformation being spread about vaccinations.
Amid the outbreak Los Angeles ordered quarantines on two university campuses last month after each reported at least one confirmed measles case.
The vast majority of US cases have occurred in children who have not received the three-way vaccines against measles, mumps and rubella (MMR), which confers immunity to the disease.
Measles is spread through casual contact with the virus, which can remain infectious in the air of an enclosed space for up to two hours after it is breathed out by someone carrying the disease.
The rate of transmission from an infected person to another person nearby who lacks immunity is about 90 per cent, and an infected person can be contagious for four days before showing signs.
Global measles immunisation rate
Alex Azar, the US health and human services secretary, has called the measles outbreak "completely avoidable".
He attacked the belief, debunked by scientific studies, that vaccine ingredients can cause autism, which has led to pockets of low vaccination rates in some communities.
US states including New York, New Jersey, Maine, Oregon, Vermont, Minnesota and Iowa are considering laws to ban parents from citing religious or personal beliefs to avoid vaccinating their children.
The Church of Scientology has never made any pronouncements discouraging its members from getting vaccinated.
A person answering the phone at the church’s media centre said no one was immediately available for comment.
According to Scientology’s website the Freewinds is home to its Flag Ship Service Organization (FSSO) and was bought in 1986.
It is described as a "religious retreat ministering the most advanced level of spiritual counseling in the Scientology religion."
What is Scientology?
In 2004 it was the scene of a surprise 42nd birthday party for Tom Cruise, Scientology’s best known member.
The website also describes it as the "pinnacle of a deeply spiritual journey," and described how it is used for "humanitarian missions" around the world.
"The Freewinds is a very special place," the website says. "It is the one place a Scientologist may go and be certain he will be able to devote himself entirely to his religious practice, and in the company of people who share his religious commitment and outlook on life in general."
It is normally docked in the Dutch Caribbean island of Curacao.
MarineTraffic.com, the vessel-monitoring website, showed the Panamanian-flagged ship docked in port near the St. Lucia capital of Castries, and indicated it had been heading next to the island of Dominica.