Major US Airlines Respond to Zika Virus in Wake of Travel Advisories

— -- U.S. airlines are keeping a close eye on the Zika virus, with some offering waivers for cancellations or ticket changes for customers traveling to affected areas. One major Latin American airline and one U.S. cruise line are also offering waivers.

Until recently, the virus has been reported in Africa, South Asia and Polynesia, but now it's also being found in the Americas.

An alert by the Pan American Health Organization was prompted last May after an outbreak of the disease in Brazil. The U.S. Centers for Disease Control and Prevention have issued a travel alert for 24 countries and territories where the virus transmission is ongoing.

United Airlines tells ABC News it is offering customers traveling to the affected regions a full refund or opportunity to rebook to a later date.

With a doctor’s note, American Airlines, LAN Airlines and TAM Airlines will allow a pregnant passenger to re-book without fees or request a full refund, according to the airline.

Southwest Airlines said it will continue to follow the established CDC guidelines, and as always, customers can change their travel itineraries without a change fee.

It is not just airlines offering a helping hand to passengers. At least one American cruise line is helping passengers reschedule too.

Carnival and its sister companies will let pregnant women and their spouses either switch to a route that doesn’t include a CDC alerted area, or hold a credit and re-book for a later date. They’re requesting a passenger wishing to take advantage of this new policy to give them some kind of verification of pregnancy, like a doctor’s note.

Delta Air Lines told ABC News it is monitoring the situation and coordinating with in-house medical professionals, the CDC and World Health Organization.

ABC News' Becky Perlow and Erin Dooley contributed to this report.