The US Center for Disease Control and Prevention has issued a travel advisory for American Samoa after a chikungunya outbreak.
The total number of people infected by the mosquito-borne disease reached more than 500.
The Center recommends travellers to American Samoa to protect themselves from mosquito bites.
It says those most at risk are people who have arthritis, high blood pressure, heart disease or diabetes as well as women who are late in their pregnancies.
It also says long-term travellers such as missionaries, humanitarian aid workers, and people visiting friends and relatives are also at high risk.