Is There an Increased Risk for Dengue Virus Infections?

CDC Issues Warning

The Centers for Disease Control and Prevention (CDC) has issued a warning about an increased risk for dengue virus infections in the United States. This is due to a record-breaking global incidence of the mosquito-borne viral disease.

Global Surge in Cases

In the first six months of 2024, countries in the Americas reported over 9.7 million dengue cases, twice as many as in all of 2023. Puerto Rico has declared a public health emergency due to the unusually high number of cases reported during the typically low season.

Impact on U.S. Travelers

Since January, 745 dengue cases have been identified among U.S. travelers who became infected abroad. Dengue cases typically increase during the warmest months that are yet to come. Last year, there were 1,829 travel-associated cases in the United States.

Climate and Transmission

Dengue transmission peaks during warmer and wetter months in tropical and subtropical regions. As global temperatures rise, cases are likely to increase. U.S. summer travel often overlaps with increased dengue activity in many countries, raising the number of travel-associated cases and local transmission in the continental United States.

No Outbreak in Continental U.S.

There is no evidence of a dengue outbreak in the continental United States. However, dengue cases have risen at an alarming rate globally, including in Puerto Rico.

How is Dengue Spread?

Dengue is spread by the bite of an infected mosquito of the Aedes species. Travelers infected abroad can bring the virus back to their communities, where local mosquitoes bite them and transmit the disease to others.

Symptoms and Risks

Most dengue infections are mild or asymptomatic, but severe cases can lead to internal bleeding, organ failure, and death. Symptoms include high fever, severe headaches, muscle and joint pain, nausea, vomiting, rash, and low white blood cell counts.

Treatment and Vaccination

There is no specific medicine to treat dengue, and no vaccines for adults or people without a previous dengue infection. The only vaccine approved in the U.S. is for children aged 9 to 16 who have had a previous dengue infection and live in areas with frequent or continuous dengue transmission.

Healthcare Guidance

The CDC urges healthcare providers to be vigilant for dengue among people with fever who have been in areas with dengue transmission within 14 days of illness onset. Infants, pregnant people, adults over 65, and those with certain medical conditions are at increased risk for severe dengue.

Complications and Warnings

Several warning signs predict progression to severe disease, including abdominal pain, persistent vomiting, bleeding from the nose or gums, and lethargy. Severe disease develops in 1 out of 20 people with symptomatic dengue.

Four Dengue Viruses

Dengue is caused by four distinct but closely related viruses. Infection with one virus generally provides lifelong protection against that specific virus, but not against the others. A second infection with a different virus carries a higher risk of severe disease.

Public Health Threat

Dengue fever poses a significant public health threat, particularly in regions with high mosquito populations and limited access to healthcare. In 2023, more than 4.6 million cases and 4,000 deaths were reported in the Americas.

Vector and Spread

The main vector for dengue is the Aedes aegypti mosquito. Six U.S. territories, including Puerto Rico and American Samoa, are classified as areas with frequent or continuous dengue spread. Local transmission in the continental U.S. has been limited to small outbreaks in Florida, Hawaii, and Texas, but cases have also been reported in Arizona and California.

Seasonal Patterns

The majority of dengue cases in the southern hemisphere occur in the first part of the year, while in the northern hemisphere, they occur in the second half.

For more information, visit the Washington Post.