A cruise ship carrying more than 4,000 passengers was denied entry to Mexico — and forced to return to the United States — after officials discovered that a woman on board is a health-care worker who handled fluids from a man dying of Ebola.

The lab tech, who worked at the Dallas hospital where Thomas Eric Duncan died, set sail from Galveston, Texas, on Sunday aboard the 1,000-foot Carnival Magic.

The woman — who has shown no symptoms of the deadly virus — waited until Thursday to quarantine herself and her husband in their room, the cruise line said in a statement.

“The individual remains in voluntary isolation,” Carnival said.

The rest of the passengers were permitted to disembark in Belize on Thursday, but the country would not allow her to go through its port to get a flight back to the United States.

On Friday, they arrived in Cozumel, Mexico, where Mexican officials refused to allow the ship to dock. The crew decided to go back to Texas, where they will arrive on Sunday.

The high-seas drama was one of several developments as the United States tries to stave off an Ebola outbreak:

The Centers for Disease Control and Prevention said New York City is now the focal point in preventing the virus’ spread, because of the high number of West Africans who enter the country through JFK Airport.

The CDC said 88 people arriving from Sierra Leone, Guinea and Liberia and suspected of having symptoms were screened in New York but cleared, despite delays caused by “hesitancy by health-care providers to examine patients or by laboratory workers to handle specimens.”

The World Health Organization admitted it botched the effort to stop the spreading Ebola outbreak in West Africa, blaming incompetent staff and a lack of information, according to an internal document.

Officials finally issued a travel ban to workers at Texas Health Presbyterian Hospital Dallas who came near Duncan.

They are barred from commercial planes, ships and trains for 21 days from their last contact with the victim. They also can’t go to bars, restaurants, grocery stores, theaters or any other locations where the public congregates. They must undergo twice-daily monitoring.

An Ebola vaccine by British pharmaceuticals company GlaxoSmithKline may not be ready for commercial use until late 2016 and should therefore not be seen as the “primary answer” to the current outbreak, the company said.

A bus full of Marines was quarantined at the Pentagon when a woman onboard who had recently visited West Africa fell ill and began vomiting in a parking lot.

She is a private contractor for the Pentagon who was headed to a Marine Corps ceremony in Washington, DC. She was later cleared of the virus.

None of the people who had contact with Ebola-stricken nurse Amber Vinson in Ohio are showing signs of illness.

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Of the 16 who have been identified, just one is under quarantine. They are being monitored daily.

Vinson traveled on a round-trip commercial flight from Dallas to Cleveland, prompting concerns over the authorities’ handling of the outbreak in the United States.

Another Dallas nurse diagnosed with Ebola, Nina Pham, 26, was in “fair condition” at a Maryland isolation unit, according to Dr. Anthony Fauci, head of the National Institute of Allergy and Infectious Diseases.

“We fully intend to have this patient walk out of this hospital,” he said.

The lab technician traveling on the Carnival Magic had boarded the ship when the CDC required employees only to self-monitor.

The CDC later notified the company that one of its passengers had been in the lab at the Dallas hospital where Duncan’s fluids were being tested.

She went into self-quarantine at the CDC’s request based on its change in monitoring protocols, Carnival spokeswoman Jennifer De La Cruz told The Post.

A doctor on the ship declared the woman symptom-free, and it has been 19 days since she handled the samples — two days shy of the 21-day incubation period for Ebola.

The woman did not have “direct contact” with the victim and has not had a fever, the US State Department said.

The two doctors and several nurses aboard the ship are monitoring the woman’s health, and all of the passengers have been told about the situation, De La Cruz said.

The cruise line offered an apology to passengers — but gave them only a $200 credit to their shipboard account and a 50 percent discount on a future cruise.

“We greatly regret that this situation and the resulting disappointment it has caused our guests,” Carnival said.

With Post Wire Services