CDC Warns of Increased Risk of Dengue Virus in U.S.

The U.S. Centers for Disease Control and Prevention (CDC) issued an advisory on June 25 to notify healthcare providers, public health authorities, and the public of an increased risk of dengue virus infections in the United States. This year, global cases of the mosquito-borne viral illness have been the highest on record.

This alert follows a similar warning from the World Health Organization (WHO) last month, and coincides with the growth of a specific breed of mosquitoes that carry the four different viruses that spread dengue fever in the U.S., as CMM previously reported.

Countries in the Americas have reported a record-breaking number of dengue cases, exceeding the highest number ever recorded in a single year. Through the beginning of the year until June 24, countries in the Americas reported more than 9.7 million dengue cases—which is twice as many as reported in the entirety of 2023 (4.6 million cases), the CDC said.

In the United States, Puerto Rico has declared a public health emergency, reporting 1,498 cases this year. Additionally, a higher-than-expected number of dengue cases have been identified among U.S. travelers—745 cases from Jan. 1 to June 24. Last year, 1,829 travel-associated cases were reported in the U.S., according to the CDC, which is the highest number on record.

Dengue symptoms are usually fever, headache, fatigue, nausea, vomiting, rash, and body aches. Dengue becomes deadlier the more times a human is infected. With increased global and domestic incidence of dengue, the CDC recommended healthcare providers promote mosquito bite prevention, increase suspicion of dengue, use appropriate diagnostic tests, and report cases of dengue quickly.

While dengue is the most common arboviral disease globally, the virus has been relatively rare in the U.S. Only a handful of outbreaks have occurred in locally transmitted cases in states with warmer climates that are habitat friendly to the specific mosquitos that carry dengue, such as Florida, Texas, Hawaii, and Arizona, CNN reported. Last year, California reported its first locally transmitted case. Other U.S. areas with frequent dengue transmission include American Samoa, the U.S. Virgin Islands, the Federated States of Micronesia, the Republic of Marshall Islands, and the Republic of Palau.

Currently no dengue vaccine is recommended for travelers or adults. In Puerto Rico, the public health departments will vaccinate children aged 9 to 16 years with a previous lab-confirmed case who live in areas with frequent transmission, CNN reported.

Last month, the WHO cleared a new dengue vaccine for global approval and another vaccine is being used in several countries in the Americas, European Union, and Asia, Reuters said.

As CMM previously reported, the WHO also recently reported that insufficient data is available on the actual and potential impacts of climate change on malaria and neglected tropical diseases, such as dengue.