SUVA, June 4 (Xinhua) -- Fiji is investigating the cause of the sudden deaths of two U.S. tourists in the nation's resort island of Denarau over the weekend, according to a statement by Fiji's Ministry of Health on Tuesday.

Fiji's health authorities are working together with the Fijian police, the World Health Organisation (WHO) and the United States Center for Disease Control and Prevention (CDC) on probing the cause of the sudden deaths of U.S. tourists.

The U.S. couple is 38-year-old David James Paul, a Lockheed Martin engineer, and his wife, 35-year-old Jane Michelle Canalog Paul. The couple, originally from Fort Worth, a city in the U.S. state of Texas, arrived in Denarau Island on May 22.

The wife died on May 25 at the clinic on Denarau Island and husband died on May 28 at a hospital in Lautoka, the second largest city in Fiji.

The couple were sick during their holiday on the island, the ministry said, adding that although they were provided medical treatment, they died after the illnesses progressively deteriorated.

While conducting investigations into the possible causes of their deaths, the ministry has also put necessary public health measures in place.

According to local media, the couple's family said early indications point to some type of virus that was strong enough to debilitate their health.

Five locals, believed to be in direct contact with the couple, are now under observation at the hospital in Nadi, Fiji's third largest city. The two security guards, two medical staff and a police officer are said to have shown symptoms similar to those of the U.S. couple before their deaths.

According to reports, more than 10 staff members from the Denarau Island Hotel were told to take paid vacations, including duty managers, housekeepers and porters.

Fijian police confirmed that the U.S. couple had a long history of globetrotting. They visited Australia and New Zealand before coming to Fiji.