The emergency was declared on 3 March.
Eight cases of dengue have been confirmed in the latest outbreak.
Questions have been raised over the declaration after no emergency was declared when people died of dengue two years ago.
American Samoa's Director of Health Motusa Tuileama Nua said the declaration means the territory could get federal money to help prevent, diagnose and treat dengue.
He pointed to the Zika outbreak in the territory for which the US government has provided US$5 million for the next three years.
Photo: Science Photo Library (The Asian tiger mosquito is one of the vectors responsible for transmitting dengue fever).