Nearly half of the dedicated members of the Central Oklahoma Parrothead Association (COPA), a Jimmy Buffett fan club, ended up very sick during their trip to the Dominican Republic in April.

Of the 114 COPA tourists which descended upon the Hotel Riu Palace Macao in Punta Cana, 54 took ill during their stay. “It was headaches, vomiting, fever, diarrhea, severe diarrhea and chills and fevers that type of thing,” member and travel agent Dana Flowers said. “About the third day in, we started to notice people not making it to events that we had scheduled and that’s when we realized that people were getting sick.”

And while at first the others assumed it was “food poisoning or something of that nature,” upon returning home, three club members have tested positive for salmonella. One of those, an unnamed Oklahoma woman, was referred to the Centers for Disease Control and Prevention (CDC), where she “escalated her testing further to see if they can determine a cause.”

The CDC and the FBI are reportedly investigating the matter, but Flowers has theories of his own. “The common thread with everybody that did get sick is that they swam in the swim-up bar pool and/or they had a drink from the swim-up bar,” Flowers said. “So it could be related to that pool.”

“I personally think it has something to do with either the pesticides or insecticides that are used around the resort or the chemicals that they use in the pool,” he added. “Those are just my own thoughts and theory on it. Also food-borne illnesses as well.”

Thus far, the Hotel Riu Palace Macao has refrained from comment.