CDC reveals 263 dengue cases, first USVI death since 2005 and testing delays of up to two months

A newly released federal investigation documented 263 confirmed cases of dengue, 15 hospitalizations and the first confirmed death associated with dengue in the U.S. Virgin Islands since 2005, during an outbreak that spanned from January 2024 to June 2025. The report also reveals that the territory initially lacked local diagnostic tests for dengue, forcing patient samples to be sent off-island and leading to turnaround times one to two month laboratories.

The results were released Thursday by the Centers for Disease Control and Prevention in their Weekly Morbidity and Mortality Report. The investigation, conducted with the VI Department of Health, examined the territory’s first dengue outbreak since 2012-2013 and documented gaps in testing and clinical preparedness that health officials then moved to fill.

According to the report, St. Croix had the highest number of confirmed infections, with 118 cases, or 45 percent of the territory’s total. St. Thomas accounted for 105 cases, or 40 percent, while St. John had 40 cases, or 15 percent.

Fifteen patients required hospitalization, with stays averaging 4.3 days and ranging from two to 14 days. One patient, a 63-year-old diabetic woman, died. The CDC identified his death as the first confirmed dengue-associated death in the territory in more than two decades.

The survey also found that 256 patients, representing 97 percent of confirmed cases, reported no travel in the two weeks before symptoms appeared. The results indicate that the overwhelming majority of reported infections were associated with transmission within the territory rather than recent travel elsewhere.

Patients ranged in age from two months to 89 years, with a median age of 44 years. Women accounted for 146 of the confirmed cases, or about 56 percent. Of the 105 infections for which the dengue virus type was identified, 101 involved dengue virus type 2, while four involved type 3. Three of the four patients with type 3 infections reported recent travel to Puerto Rico.

Testing delays revealed during outbreak

One of the most important findings of the investigation was the lack of local diagnostic testing for dengue fever during the early stages of the epidemic.

In August and September 2024, the CDC and the Department of Health conducted a surveillance and clinical needs assessment that identified two major barriers to dengue case detection and management. Health care providers reported limited experience treating suspected dengue infections over the previous decade and a need for additional training in clinical management, testing, and disease reporting.

The assessment also found that no local diagnostic tests were available for dengue, requiring samples to be transported outside the Virgin Islands for analysis. According to the CDC, this resulted in turnaround times of one to two months before test results were available.

The Ministry of Health responded by introducing dengue diagnostic testing at the territorial public health laboratory in October 2024. The CDC reported that this change reduced turnaround times to less than a week.

During fall 2024, the department also visited 30 clinics and conducted 20 clinical training sessions covering dengue management, screening and reporting. A helpline was established in October to provide additional guidance to healthcare providers, while an electronic online disease reporting platform was rolled out during the same period.

The CDC has not said how many patients experienced the longest testing delays or determined whether those delays contributed to individual hospitalizations or the fatal case.

The epidemic has spread across the territory

The report shows the outbreak grew unevenly between the three islands, with St. Thomas and St. John recording the bulk of infections in early 2024 before cases rose sharply on St. Croix.

Between July and September 2024, St. Thomas recorded 77 confirmed cases and St. John 26. During the same period, St. Croix recorded six.

The trend then changed. From October to December 2024, St. Croix recorded 64 confirmed infections, compared to five on St. Thomas and one on St. John.

St. Croix remained the center of reported infections during the first three months of 2025, accounting for all 42 cases recorded during that period. Five more cases were reported on the island between April and June 2025, with no additional confirmed cases for St. Thomas or St. John in the first half of this year.

The CDC reported that the annual incidence of dengue in the territory reached 2.5 cases per 1,000 inhabitants in 2024.

Mosquito control and public awareness

As infections spread, the Department of Health worked with the CDC and the Puerto Rico Vector Control Unit on mosquito control and public education campaigns in affected communities.

The response included door-to-door activities in 25 communities where dengue cases were reported. Teams surveyed 256 residential yards for breeding sites associated with the Aedes aegypti mosquito, which transmits dengue fever, and applied mosquito larvicide to 167 households.

Approximately 900 space repellent devices have been distributed. These devices release small amounts of insecticide into the surrounding air without requiring electricity or heat.

The response also included the distribution of mosquito nets for cribs in seven daycare centers, orphanages and maternal care facilities.

Public education efforts reached 420 homes and 54 schools, alongside activities at 10 public events and four press conferences.

In their assessment, federal and territorial health officials concluded that the outbreak response resulted in local diagnostic testing, expanded clinical training, and increased mosquito control and public education activities.

The CDC has emphasized the need to maintain these capabilities between outbreaks so that the Virgin Islands can respond quickly to future increases in dengue infections.

Previous monitoring results

The Consortium previously reportedd on the dengue epidemic in the territory as infections increased in 2024 and continued in 2025.

In an April 2026 review of the Department of Health’s annual surveillance report, the Consortium reported that the territory recorded 47 confirmed cases of dengue fever in the calendar year 2025, alongside the modernization of its electronic disease surveillance system.

The newly released CDC survey provides a more detailed look at the outbreak period, including the total of 263 cases, the number of confirmed deaths, island-by-island transmission patterns, and diagnostic delays identified in 2024.

The federal report covers cases through June 2025 and does not establish whether laboratory turnaround times and the territory’s testing capacity remained at levels reached after the October 2024 improvements.