St. Lucia prevented passengers and crew members from getting off a cruise ship at its port this week after someone on the vessel was diagnosed with measles, according to a senior health official on the island.
"We thought it prudent that we quarantine the ship," Dr. Merlene Fredericks-James, the Caribbean nation's chief medical officer, announced this week, saying the decision was based on information from "two reputable sources that there was a confirmed case on board a cruise ship" that arrived at the island on Tuesday.
"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," a quarantine was deemed the best course of action, she said.
In January, St. Lucia said it has been free of local transmission of measles since 1990.
The quarantine affects nearly 300 passengers and crew members aboard a ship called Freewinds, reports NBC News, citing the St. Lucia Coast Guard.
Freewinds is a 440-foot Caribbean-based ship owned and operated by the Church of Scientology. On its website, the church describes the boat as "a religious retreat ministering the most advanced level of spiritual counseling in the Scientology religion," saying the vessel is used for religious conventions, seminars and other services.
The church did not respond to NPR's request for comment about the quarantine.
In an update on the case Thursday, St. Lucia's Ministry of Health and Wellness said it is providing the measles vaccine to people on the ship.
"Today, the ship's doctor requested 100 doses of the measles vaccine and this is currently being provided from our supplies, at no cost," the agency said.
NBC News reports that the infected person on the ship is a female member of the crew, who has been isolated and is reported to be in stable condition.
Highly contagious, though vaccine preventable, measles can spread when an infected person sneezes, coughs or even breathes. The Centers for Disease Control and Prevention says a person can catch it simply by being in the same room an infected person was in — even up to two hours after the infected person left.
Urging vigilance aboard the ship, St. Lucian health officials warned that "the incubation period for measles ranges from 10 to 12 days, before symptoms in exposed persons occur."
Fredericks-James says the decision to quarantine the cruise vessel was informed in part by news of the rapid spread of measles in parts of the United States.
The U.S. is battling its biggest measles outbreak since the disease was declared eliminated in 2000. The CDC says its latest tally shows that more than 700 cases have been confirmed in nearly two dozen states so far this year.
Most parents in the U.S. opt to vaccinate their children, the best method of protection, the CDC says, but misinformation about vaccine safety has spurred some to opt out.
The majority of cases in the U.S. have occurred in New York, mainly affecting Orthodox Jewish communities. Health officials say it began with an unvaccinated child picking up the disease on a trip to Israel, a country dealing with its own outbreak. Once unvaccinated communities are exposed, it becomes difficult to stem the spread of measles.
On Monday, New York City announced the closure of two additional Jewish schools for failing to comply with an order to keep unvaccinated students home and maintain medical records on-site, bringing the number of shuttered schools to seven.
Last month, officials in California rushed to tamp down measles' potential spread after a UCLA student came down with a case and another infected person visited a California State University library in Los Angeles. Quarantines were declared at the LA campuses of both schools, affecting hundreds of students and staff members, unless they could show proof of vaccination.
As for the fate of the quarantined ship, Marinetraffic.com said Freewinds was moored in St. Lucia on Thursday, but it's scheduled to arrive at the Caribbean island of Dominica on Friday.
"We have no jurisdiction over their next destination," Fredericks-James told NBC News.
On Thursday, St. Lucia's health agency said it has been discussing the measles case with regional organizations, including the Caribbean Public Health Agency.