Dengue: What Is It, and How Can I Prevent It?

What are Dengue and Dengue Virus?

Dengue or dengue fever is a disease caused by a group of dengue viruses (DENV). Four different types of DENV commonly cause disease in humans, each denoted by a number (DENV-1, DENV-2, DENV-3, and DENV-4) (CDC, 2024a). When someone is not talking about a specific type of dengue virus, they may only write it as dengue virus or DENV. Many people infected with DENV experience little to no symptoms (CDC, 2024c). People who do experience symptoms can experience different ones depending on the type of DENV they are infected with. The most common symptoms can include fever, pain (including behind the eyes, in the joints, muscles, and/or bones), rash, and nausea (CDC, 2024c). Although uncommon, dengue symptoms can become severe, including abdominal pain, vomiting, and bleeding from the nose or gums (CDC, 2024c). If you have dengue symptoms, please consult your medical provider for testing and diagnosis.

Dengue is a vector-borne disease, meaning that the virus that causes this disease is transmitted through the bite of insects or other animals. Mosquitoes are the vectors responsible for transmitting dengue viruses between humans. The yellow fever mosquito (Aedes aegypti) is the primary species responsible for transmitting or vectoring DENV. The tiger mosquito (Aedes albopictus) may also act as a vector of DENV (Carrington & Simmons, 2014). To become infected with DENV, a person would need to be bitten by one of these mosquitoes that had already bitten an infected person.

Where Does the Risk of Dengue Exist?

Dengue affects much of the world, with the Americas, portions of Asia, and islands in the western Pacific being the most seriously affected (WHO, 2024). In North and South America, nearly 500 million people are at risk of dengue as they live in areas with mosquitoes that can transmit the virus (PAHO, 2024). Dengue risk tends to be highest during or after peak mosquito season in an area. In North America, mosquito activity peaks from June - October, or until colder temperatures begin, meaning the risk for mosquito-borne diseases peaks in the latter half of the year (PAHO, 2024). Alternatively, mosquito-borne disease risk in the southern hemisphere peaks early in the year. This can vary as mosquito activity can depend on many things, including temperature, humidity, and availability of standing water.

In recent years, including 2023 and 2024, locally acquired DENV infections have occurred in the United States and its territories, but most dengue cases in the United States are travel-related cases (CDC, 2024b). Locally acquired or endemic cases mean a person was infected near home and not while traveling to other areas. Disease cases where someone was infected while away from home and traveling are usually called travel cases. During 2023 and 2024, no locally acquired cases of dengue virus were reported in Pennsylvania, but 40 and 60 travel-related cases were reported in the state for those years, respectively (CDC, 2025a, 2025b). Although the virus and the primary vector are not known to be established in Pennsylvania, another potential vector, the tiger mosquito (Aedes albopictus), is found in the southeastern and western portions of the state (Taber et al., 2017). Other states, including Florida, Texas, Arizona, Hawaii, and California, have had locally acquired cases in recent years, meaning that mosquitoes in those areas have been carrying and transmitting the virus (CDC, 2025a, 2025b).

How Can I Reduce My Risk?

Although a vaccine exists for the dengue virus, it is only given to those who live in areas with dengue virus transmission. Secondary infection with different dengue viruses can lead to more severe symptoms, so dengue vaccines should provide sufficient immunity to the four types of dengue viruses to prevent potentially severe symptoms associated with secondary infections of DENV. There are no vaccines or preventative medications for U.S. travelers who do not live in areas with local dengue virus transmission (CDC, 2024a). This makes preventing and reducing mosquito bites essential when traveling where dengue or other vector-borne diseases are common. Pack and wear an EPA-approved insect repellent and loose-fitting, long-sleeved clothing to help prevent mosquito and other insect bites. If you are unsure whether vector-borne diseases are common in your travel destination, you can check local and global public health websites to help prepare for your trip. If you are not staying in a building with window screens or air conditioning, bed nets can help prevent mosquitoes from biting while resting or sleeping. If you recently returned from a trip to an area with local dengue cases and feel any symptoms like those of dengue, visit your healthcare provider.

In addition to taking preventive steps while traveling, everyone can prevent and reduce their risk of mosquito bites at home. While outside, one should also wear insect repellents and loose-fitting, long-sleeved clothing. All mosquitoes require water for their immature stages, and the types of mosquitoes that can transmit DENV lay their eggs and develop in containers or plants that hold water. Any containers left outside should be removed or emptied once per week to prevent mosquitoes from using them. If rain barrels are used, they should be covered with a lid or fine mesh that prevents insects from passing through. Maintain or add window and door screens to prevent mosquitoes from entering the home. Taking steps to avoid mosquito bites at home and when traveling can help reduce your risk of being bitten.

References

Carrington, L. B., & Simmons, C. P. (2014). Human to mosquito transmission of dengue viruses. Frontiers in Immunology, 5.

Centers for Disease Control and Prevention. (2024a, May 14). About dengue. Retrieved January 09, 2025, from

Centers for Disease Control and Prevention. (2024b, May 14). Data and statistics on dengue in the United States. Retrieved January 17, 2025.

Centers for Disease Control and Prevention. (2024c, May 14). Symptoms of dengue and testing. Retrieved January 10, 2025.

Centers for Disease Control and Prevention. (2025a, January 16). Dengue current year data (2024). Retrieved January 17, 2025.

Centers for Disease Control and Prevention. (2025b, January 16). Dengue historic data (2010-2023). Retrieved January 17, 2025.

Pan American Health Organization (2024, May 18). Dengue. Retrieved January 10, 2025.

Taber, E. D., Hutchinson, M. L., Smithwick, E. A. H., & Blanford, J. I. (2017). A decade of colonization: The spread of the Asian tiger mosquito in Pennsylvania and implications for disease risk. Journal of Vector Ecology, 42(1), 3-12.

World Health Organization. (2024, April 23). Dengue and severe dengue. Retrieved January 10, 2025.

Disclaimer: This project was supported by award number NU50CK000637 from the Centers for Disease Control and Prevention. Its contents are solely the responsibility of the authors and do not necessarily represent the official views of the Centers for Disease Control and Prevention.