CDC Cuts Virgin Islands Dengue Testing From Months to Days

Laboratory delays of up to two months complicated the response to a dengue outbreak that infected 263 people in the U.S. Virgin Islands between January 2024 and June 2025. A Centers for Disease Control and Prevention investigation published October 15 in the Morbidity and Mortality Weekly Report found that establishing local diagnostic testing in October 2024 reduced turnaround times to less than one week.

The outbreak resulted in 15 hospitalizations and one confirmed dengue-associated death, the territory's first since 2005. The CDC conducted its investigation with the Virgin Islands Department of Health to examine transmission patterns, diagnostic limitations and public health measures implemented during the outbreak.

According to the CDC report, St. Croix recorded 118 confirmed cases, St. Thomas had 105 and St.

John reported 40. Of the 263 patients, 256, or 97%, had not traveled during the two weeks before symptoms began, indicating that infections were overwhelmingly associated with local transmission.

Hospital stays averaged 4.3 days and ranged from two to 14 days. The patient who died was a 63-year-old woman with diabetes. Patients ranged in age from two months to 89 years, with a median age of 44, while women accounted for 146 cases, approximately 56% of the total.

Among 105 infections for which the virus type was identified, 101 involved dengue virus type 2 and four involved type 3. Three patients with type 3 infections had recently traveled to Puerto Rico, according to the investigation.

During an August and September 2024 assessment, the CDC and territorial health officials identified two major obstacles: limited clinical experience with dengue and the absence of local diagnostic testing. Samples had to be shipped off-island, leaving doctors waiting weeks or months for laboratory confirmation.

In August 2024, Chief Medical Officer Dr. Tai Hunte-Ceasar warned that limited testing and care-seeking made it difficult to measure the outbreak's full extent.

"Our true dengue burden is unknown," Hunte-Ceasar said at a Government House press briefing, as reported by the VI Consortium.

The Department of Health introduced testing at the Territorial Public Health Laboratory in October 2024. The agency also visited 30 clinics, delivered 20 clinical training sessions during fall 2024, established a telephone hotline for medical providers and introduced a web-based electronic disease-reporting system.

The CDC did not establish how many patients experienced the longest testing delays or determine whether those delays contributed to individual hospitalizations or the death.

Transmission patterns shifted between the islands during the outbreak. From July through September 2024, St. Thomas recorded 77 cases and St.

John had 26, compared with six on St. Croix. From October through December, St.

Croix recorded 64 cases, while St. Thomas had five and St. John had one.

St. Croix remained the main center of reported infections in early 2025, accounting for all 42 confirmed cases recorded across the territory from January through March. Another five cases were recorded there between April and June, with no additional confirmed cases reported on the other two islands during that period. The CDC calculated that annual dengue incidence reached 2.5 cases per 1,000 residents in 2024.

Mosquito control efforts were conducted by territorial health officials in collaboration with the CDC and the Puerto Rico Vector Control Unit. Teams visited 25 affected communities, inspected 256 residential yards for mosquito breeding sites and applied larvicide at 167 homes. They also distributed approximately 900 spatial-repellent devices designed to release insecticide into surrounding air without electricity or heat.

Public education activities reached 420 households and 54 schools, alongside programs at 10 public events and four press conferences. Mosquito nets for cribs were distributed to seven childcare, orphanage and maternal healthcare facilities.

The CDC report emphasized the importance of maintaining diagnostic, surveillance and mosquito-control capacity between outbreaks. The territory's response established local laboratory testing and expanded clinical training, reporting systems and community prevention activities.

The findings also come as Florida reports locally acquired dengue infections. According to the Florida Department of Health's weekly arbovirus report, the state recorded 368 locally acquired cases as of October 10, 2026, including 310 associated with Hillsborough County and 37 with Pinellas County. Florida also recorded 288 travel-associated cases, including 182 in Miami-Dade County.