On Tuesday, the US Centers for Disease Control and Prevention issued a warning to doctors to be vigilant for cases of dengue. A global surge in dengue cases is heightening the risk of disease transmission in the US.
The number of dengue cases has been escalating worldwide as the climate warms due to the human-induced climate crisis. The Aedes aegypti and Aedes albopictus mosquitoes, responsible for spreading the disease, thrive in warmer and wetter conditions.
In previous years, dengue was uncommon in the continental US, primarily affecting individuals who had traveled to regions where the disease is prevalent. However, this year has seen a higher-than-expected number of dengue cases among US travelers, with 745 cases reported through June 24, according to the CDC.
In 2023, the US reported 1,829 travel-associated dengue cases, the highest number since dengue became reportable in 2010. Last year, twenty-three countries experienced outbreaks, resulting in over 5 million cases and 4,000 deaths in the Americas alone.
Several states with warm climates and suitable mosquito habitats, such as Florida, Texas, Hawaii, and Arizona, have witnessed locally-transmitted dengue outbreaks. California recorded its first locally transmitted case in Pasadena last year.
The CDC’s latest warning highlights a record number of global infections in 2024. Cases in the Americas have surpassed the previously recorded highest number, with over 9.7 million individuals infected with dengue, double the total cases in 2023.
Puerto Rico declared a public health emergency due to the high number of dengue cases. Other areas with frequent dengue transmission linked to the US include American Samoa, the US Virgin Islands, the Federated States of Micronesia, the Republic of Marshall Islands, and the Republic of Palau.
The CDC is urging doctors to test patients displaying dengue-like symptoms, especially those who have recently traveled to regions where the disease is endemic.
Symptoms of dengue typically manifest about a week after being bitten by an infected mosquito. While a significant portion of infections are asymptomatic, common symptoms include fever, vomiting, muscle and joint pain, headache, and nausea.
Severe cases of dengue can lead to serious complications such as severe bleeding, respiratory distress, and organ failure, with mortality rates as high as 13% in untreated patients.
Individuals at higher risk for severe dengue include infants, pregnant individuals, the elderly, and those with underlying medical conditions.
While there is no specific medication for dengue, supportive care involving fluids and rest is recommended. Sanofi Pasteur ceased production of the Dengvaxia vaccine, the only dengue vaccine available, citing low demand. However, public health departments in Puerto Rico will continue administering the vaccine to children aged 9 to 16 with confirmed cases until the doses expire in 2026.
The CDC launched an emergency response in April of this year to address the escalating dengue caseload in the US. The agency has expanded lab capabilities and is collaborating with local authorities to enhance disease surveillance.
To prevent dengue, individuals are advised to use insect repellent outdoors, especially when in regions where dengue is prevalent. Wearing loose-fitting, long-sleeved clothing and using air conditioning or window screens to keep mosquitoes out can also help mitigate the risk of infection.
