Samoa's Ministry of Health says it has recorded 220 cases of dengue fever in the past eight weeks and data shows increasing weekly totals of people affected throughout July.
It says the serotype three strain has been identified and most of the cases are from the North West Upolu region.
Children and teenagers have been the largest group affected by the mosquito borne illness.
There have been 15 admissions to hospital with four children seriously unwell but no reported deaths.
The Ministry says it is now reserving rapid laboratory testing for the sickest patients.
Mosquito spraying, increased surveillance and public education are all underway throughout Samoa to prevent dengue spreading.
In neighbouring American Samoa the dengue impact has been more severe, with four deaths and 75 people hospitalised over recent months.