A New Jersey man is at least the eighth person to die while on vacation in the DR in the last 12 months, CBS News has learned. His cause of death has not been released. His death comes as more Americans are reporting incidents of mysterious illnesses and deaths in the Dominican Republic.

Joseph Allen's family says he traveled to the Dominican Republic frequently and was in good health, reports CBS News' Mola Lenghi. They say the 55-year-old was staying at Terra Linda Resort in Sosua last week with friends, who say he had complained about being hot at the pool. He went to take a shower and lie down for the night and was found dead the next day.

At least seven other Americans have died in the Dominican Republic in the last 12 months. Local autopsies concluded most died of respiratory problems, or a heart attack.

Mark Hurlbut Jr. says his father died from heart and respiratory problems last June in Punta Cana.

"Some seemingly healthy people seem to be having heart attacks out of the blue," Hurlbut said. "Had I known then what I know now, I would have fought tooth and nail to have his remains brought back here and have an American autopsy done."

Tourist groups are also reporting concerns. Five members of an Oklahoma high school group staying at the Hard Rock Hotel & Casino became violently ill after eating at a Japanese restaurant and more than 50 Jimmy Buffett fans were sickened while on an annual trip in April. At least one tested positive for salmonella last week.

Joseph Allen's family is trying to get his body home and we are still waiting on FBI toxicology reports for the three deaths that occurred in May.

The U.S. embassy in Santo Domingo says there is no proof at this point they're linked.

Health officials say heart attacks are the most common cause of death for Americans on vacation.

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