When the outbreak of the Zika virus in Brazil came to international attention a few years ago, the outbreak was largely over by summer.

But a new outbreak of the disease that makes its victims bleed has created a surge of people leaving the country by plane and sea to settle in the United States and Europe, including some of the biggest financial titans in the world. A recent travel tip on social media has even been the subject of an open letter to Mark Zuckerberg, on why his young children should travel with their father to Africa instead of taking a flying taxi to the taxicab office.

Their destinations seem equally bewildering, though there is a good chance they will never encounter a mosquito. The rapidly spreading outbreak is raising concern over a potentially catastrophic exodus of people, especially retirees who would rather risk their health and retirement funds than go back to an environment they know as a horror show.

“This is a panic,” said Dr. Ailton Misiachi, a public health specialist in Bauru, Indonesia, who has a simple explanation for the surge in travelers who are quietly renouncing lives they thought would last for decades in Central and South America: Zika is nosing into their favorite places.

Zika is a mosquito-borne virus that can cause birth defects in women if a fetus is too small to survive.

It has gotten so bad in parts of Latin America that officials are scratching their heads. Zika, which was thought to be contained by last summer, has now spread to Africa and is close to southern Europe, as well as parts of Asia. Last week, the World Health Organization declared a global emergency over Zika’s spread.

“I don’t believe it’s gone anywhere else,” said Dr. David Beasley, the outgoing WHO director-general, as he announced the move.

The fervor that has gripped travel advisers and the public has the real threat of a mass exodus of people who have built their lives around a location and now, suddenly, have to look elsewhere.

“Everybody has plans to go there, and they will need to alter them and renegotiate some of those plans,” Dr. Anthony Fauci, a researcher at the National Institutes of Health who works closely with researchers in Latin America, said this week.

These plans may include an evacuation of their assets, real estate, stock portfolios and retirement savings in case the destination stops providing the promised financial support or other benefits.

For moneyed Germans, their second homes in Portugal and Italy are suddenly not so safe. The London Times reported that more than 1,000 Germans have left South America recently and headed to Britain.

They were buying second homes while still young, and they are now buying vacations, driving with a much lower consciousness, the paper reported. “The conversation is very much about Zika,” said James Traynor, a partner at the real estate company Venaria Soho, which sells vacation homes. “I’ve never seen anything like it.”

Sales at a Brazilian villa development west of Rio de Janeiro are “through the roof,” he added.

“A lot of them would have been buying second homes for 50 or 60 years, and it suddenly occurred to them that these places are not as safe as they thought,” Mr. Traynor said.

The money poured out of Brazil in 2016, sending the real estate market there plunging, said Ana Paula, a broker in Maribor, the Croatian capital. Now that the second-home sales are picking up again, “everything is off the charts,” she said.

Spanish Health Minister Carmen Calvo apologized to her countrymen for the scare, saying: “If a citizen feels that he has been evacuated from his country because he is allergic to the Zika virus or because he’s putting his health at risk because he’s pregnant, that’s unacceptable.”

The owners of these real estate investments are telling themselves there is no reason to fear re-entry to Brazil, Mr. Traynor added.

“These aren’t people selling fish at the market,” he said. “They are living the dream life. And nobody wants to give that up.”