In a statement issued late morning Fiji's health ministry said influenza had been ruled out and at this stage they did not believe there was any risk to the public.
The authorities said it would be premature to speculate further on the cause of death until the investigation is complete.
David Paul and Michelle Calanog Paul from Fort Worth in Texas arrived in Fiji for a holiday on 22 May and reportedly died within days of each other.
They were aged in their thirties and described by relatives as very fit and healthy.
