Samoa's Ministry of Health has reported two deaths from acute fever and rash, saying it is now an outbreak.
A press statement from the Director General, Leausa Toleafoa Dr Take Naseri, says there have been 21 recorded cases as of earlier this week with four people hospitalised.
The cases are suspected to be chikungunya virus, similar to dengue fever, but results are yet to be confirmed.
Three children and one man have been admitted to the intensive care unit.
The ministry says collaboration with other government agencies, and media campaigns, aim to raise awareness of the outbreak and help its containment.
Samoa has also sought assistance from the Ministry of Health's development partners including the Secretariat of the Pacific Community and the World Health Organisation.
In neighbouring American Samoa, there have been more than 300 confirmed cases of chikungunya.