Reviewed by: Leah Mische, M.D., Medical College of Wisconsin
Bottomline: This MMWR article reviews the significant spike in cases of dengue in the United States in 2024, with both imported and autochthonous cases reported.
In 2010-2023, the average annual cases of dengue reported in the US to ArboNET was 828. In 2024, there were 3,798 cases reported, a 359% increase in cases. 59.3% of cases were confirmed, with 40.7% probable. Of the cases that underwent serotyping, 54.8% were DENV-3 followed by 23.2% DENV-4. The vast majority (97.2%) were associated with travel (travel confirmed 2 weeks prior to onset of symptoms) and were likely imported but a small minority (2.8%) were documented as likely locally acquired.
Of the imported cases, 34.1% were diagnosed in individuals who had traveled to the Caribbean, especially Puerto Rico and the Virgin Islands, both of which had outbreaks of dengue in 2024. When country of acquisition was known, the most common implicated countries were Mexico (25.4%), Cuba (18.1%), and India (6.4%).
Of the locally acquired cases in 2024 alone, there were eighty-five cases in Florida, eighteen in California, and two in Texas. 66.7% of locally acquired cases were in persons of Latino ethnicity. Of note, per this report, about 75% of the United States has a climate appropriate for the Aedes mosquito vectors that are capable of transmitting dengue, raising concern that dengue has the very real potential to become a locally acquired infection in the United States again.
Dengue is one of the most common causes of fevers in the returning traveler and can cause severe illness and even death. Indeed, in this group of infected individuals in 2024, 36.1% were hospitalized, 2.8% developed severe dengue, and 0.2% died from the infection. The MMWR advises an urgent need for improved measures to slow the importation of the virus and advises improving education during pre-travel visits to focus on mosquito avoidance, including the use of appropriate repellant, wearing loose-fitting long-sleeved pants/shirts, using window screens, and eliminating standing water containers when visiting regions with endemic dengue.
Reference:
Kiplagat SJ, Rodriguez DM, Rivera A, Paz-Bailey G, Wong JM, Adams LE. Increase in Travel-Associated and Locally Acquired Dengue Cases — United States, 2024. MMWR Morb Mortal Wkly Rep 2026;75:227–233. DOI: http://dx.doi.org/10.15585/mmwr.mm7518a1.