Mexico is the top international destination for U.S. travelers; nearly 30 million Americans visited the country last year alone.

People come to Mexico for the beautiful beaches and just unwind and let loose. But one Wisconsin family of four who visited in January to do just that lost their 20-year-old daughter. She was found face down in a swimming pool after drinking.

The U.S. State Department is now warning Americans to consume alcohol in moderation while visiting Mexico, and to get medical help if they feel sick while drinking in the country.

"It's not a new concern in Mexico," says CBS News travel editor Peter Greenberg, "but what you have here is a perfect storm of more than one incident happening to people who don't know each other in different resorts. That is definitely a reason for concern."

In January, Abbey Conner and her family arrived at Paradiso del Mar for their vacation. It's one of the 10 Iberostar Hotel & Resort locations in Mexico.

Abbey Conner died at a resort in Mexico after allegedly drinking tainted alcohol. CBS News

By dinner time, Abbey and her 22-year-old brother Austin were reportedly found unconscious in the pool after drinking at the resort bar. Both were taken to the hospital. Abbey died days later.

The Milwaukee Journal Sentinel reports dozens of other people also claim to have been sickened by bad alcohol at Mexican resorts, and some of them also blacked out.

"They said I couldn't get out of the pool and I wasn't even able to stand up in the pool," Kathy Daley told the Sentinel.

Daley says she woke up in a Cancun hospital after staying at an Iberostar hotel.

"They said I was vomiting all over the place and they had to call the hotel doctor," she said.

More than 1.4 million gallons of tainted alcohol has been seized in Mexico since 2010. Some of the counterfeit alcohol is said to contain pure industrial ethanol -- an ingredient used in many rubbing alcohols.

Iberostar Hotels and Resorts told CBS News they "only purchase sealed bottles that satisfy all standards."

The state department tells CBS News that people who become sick after drinking in Mexico should immediately contact the nearest U.S. Embassy or consulate. The Iberostar hotel chain's management also said they were deeply saddened by the incident and that the safety and satisfaction of their guests is of the utmost importance.