Dengue Fever Cases in Hawaii Raise Concerns

Hawaii has recorded about a dozen cases of dengue fever, which has prompted health officials to issue urgent warnings. The state’s Department of Health recently confirmed a case on Oahu linked to international travel.

Details about the individual’s travel are limited, but the health department indicated it was likely a region where dengue is prevalent, possibly in Southeast Asia, South America, the Caribbean, or Africa.

With 12 cases reported so far in 2025, the state is nearing last year’s total of 16. The CDC noted that this year, there have been 2,725 confirmed cases of dengue across 46 states and territories in the U.S., mostly from local transmissions, with six states being the most affected. Florida, Texas, Hawaii, Arizona, and California are among these states.

While there has been an uptick in cases recently, it’s important to note that the figures are decreasing compared to last year’s outbreak, which resulted in about 8,000 infections.

Transmitted through mosquito bites, dengue fever is often called ‘break-bone fever’ due to the intense joint and muscle pain reported by those infected. It’s concerning that about 5% of individuals with symptoms may experience severe complications like bleeding or respiratory distress.

Hawaii’s cases thus far have been associated with travelers to endemic regions, leading health officials to advise anyone returning from such areas to consult with a doctor if symptoms develop within two weeks.

Dengue-carrying mosquitoes are prevalent in tropical and subtropical climates, including Central and South America, Africa, South Asia, and the Pacific Islands. In the U.S., dengue is particularly common in Florida, Texas, California, and the territory of Puerto Rico, which has reported the highest number of cases at 2,152 this year.

Though about 400 million people contract dengue annually, surprisingly, eight out of ten show no symptoms. Those who do typically suffer from high fever, a blotchy rash, and pain in their muscles and joints, as well as behind the eyes. In rare extreme cases, the condition can lead to severe vomiting and even internal bleeding, which can be fatal if untreated, with a mortality rate of about 13% for those who don’t receive care.

Currently, there is no antiviral for dengue, but the World Health Organization suggests that promptly replacing lost fluids can reduce the mortality rate significantly. While a vaccine exists and is approved for children aged nine to 16, its manufacturer, Sanofi Pasteur, has stopped production due to low demand, and available doses are expected to deplete by 2026.

Dengue cases have surged in Latin America, often associated with the El Nino weather cycle, which increases rainfall and creates stagnant water where mosquitoes breed. Additionally, rising temperatures have expanded the mosquitoes’ active seasons and geographical range.

In areas where dengue is less common, travel-related infections have contributed to local outbreaks, as infected individuals can spread the virus to local mosquito populations. The CDC advises travelers to high-risk areas to use insect repellent, wear long sleeves and pants, and seek accommodations with air conditioning or screens to minimize the risk of mosquito bites.