What is Dengue and How Does it Spread?
Dengue virus is transmitted by certain Aedes mosquitoes and considered a major global threat as our world’s urban landscape grows. Beyond the increase in desirable habitats for the container-breeding species, the virus has four strains (multiple serotypes) making it complicated for medical professionals to manage. Chikungunya virus shares similar symptoms to dengue and provides those bitten with immunity from future chikungunya infections. Unfortunately, with multiple strains of dengue, an individual is more likely to be hospitalized or die if infected with more than one serotype. Those previously infected or individuals with a weakened immune system should take even greater precautions.
Signs and Symptoms of Dengue
Symptoms of Dengue Infection
- Symptoms occur 3-7 days following exposure, and are characterized by a very high fever (104°F), rash, severe headache, and excruciating pain in the muscles and joints commonly known as “break-bone fever.”
- 1 in 20 infected people will develop severe dengue hemorrhagic fever, which can result in internal bleeding, continued vomiting, and in rare cases (>1%), death.
- Travelers to known endemic areas should consult with their physician immediately if they exhibit any of these symptoms.
- There is no cure for dengue fever, but vaccines are currently in development.
Treatment of Dengue Infection
- Currently, no specific medications exist to treat dengue virus infection or disease.
- Treatment for symptoms includes rest and the use of acetaminophen to relieve fever and pain. Avoid aspirin.
- Patients should also be advised to drink plenty of fluids if diagnosed.
- If anyone has recently traveled to a known endemic area and are displaying any of the symptoms of dengue infection, they should consult their physician immediately.
Severe dengue (dengue hemorrhagic fever) can occur with warning signs three to seven days after symptoms began. If temperature declines and the following symptoms surface seek immediate medical attention: severe abdominal pain, continued vomiting (may include blood), bleeding nose or gums, rapid breathing, or fatigue.
Dengue and the United States
In 2024, locally acquired dengue cases rose significantly compared to 2023—jumping from 1,104 cases in 2023 to 6,076 in 2024. These outbreaks occurred in several states, including California, Florida, and Texas, highlighting a notable increase in mosquito-borne transmission in certain regions compared with the previous year.
United States territory, Puerto Rico, faced a significant outbreak, leading to a public health emergency as over 5,700 cases were documented. The U.S. Virgin Islands also saw an uptick in locally acquired cases.
Dengue Fever Vaccine
Sanofi-Pasteur is discontinuing its dengue vaccine, Dengvaxia, due to low global demand. The CDC and Puerto Rico Department of Health will continue informing health professionals about its recommended use. Dengvaxia remains safe and effective when used as advised. Two other dengue vaccines are in development but not yet available in the U.S. To reduce the transmission of dengue, citizens should focus on mosquito bite prevention and control.
A Global View of Dengue
Dengue is most often transmitted by Aedes aegyptiand Aedes albopictus mosquitoes. These species are also responsible for the transmission of chikungunya virus, yellow fever virus, and more recently Zika virus. The below maps highlight parts of the world that provide a suitable environment for each species.
Know Your Aedes Mosquitoes
Aedes aegypti, the yellow fever mosquito, is characterized by a silvery-white “lyre-shaped” pattern of scales on its thorax. It is a peridomestic species found not far from human dwellings. They are primarily early morning or late afternoon feeders, but females can also take a bloodmeal at night under artificial illumination. Typically, Ae. aegypti fly only a few hundred yards from their breeding sites.
Aedes albopictus, the Asian tiger mosquito, is a black mosquito with distinctive silvery-white scales and a white “racing stripe” on its thorax. First reported in the USA in 1983, this species has become one of the most challenging mosquitoes to control and, unlike most mosquitoes, actively bites during full sunlight. Beyond being a daytime biting nuisance, the Asian tiger mosquito is also capable of transmitting several diseases, including West Nile virus, Zika, chikungunya, and several forms of encephalitis as well as dengue. The presence of this invasive species has become a major public health concern in many locations across the country.
Both species utilize containers to breed, and educating the public on how to eliminate their backyard larval habitats is one key to keeping these invaders under control. Larvae can be found in a variety of artificial containers, including buckets, tires, cans, and flower pots. Homeowners should also inspect rain gutters for clogs, gardening equipment, and backyard children’s toys.
Controlling Aedes aegypti/albopictus and Dengue
An Integrated Mosquito Management (IMM) program is essential to helping prevent mosquito bites and transmission of serious vector diseases in the United States. As part of an effective IMM program, VDCI recommends a 4-pronged approach to target all phases of the mosquito’s life cycle.
Community understanding of how to properly eliminate mosquito breeding habitat and take personal protective measures is critical. Furthermore, distribution of educational pieces is important for treating symptoms and aids public health officials in identifying dengue problem areas.
2: Surveillance
In order to understand the risk and address the threat appropriately, it is critical to determine the mosquito distribution, density, and species composition throughout the target area. Surveillance will also provide direct evidence of an increased transmission risk of dengue virus.
When mosquito larvae are detected in an area, trained and experienced ground crews reduce breeding habitat when possible, then preferentially apply Bacillus thuringiensis var israelensis (Bti) to remaining areas of standing water, stagnant pools, and water-holding containers. Aerial and ground application of larvicide via ULV equipment can provide control in hard to reach container habitats.
VDCI recommends the deployment of two-person teams to conduct targeted ULV applications combined with residual “barrier” applications via backpack applicators to mosquito harborage areas near homes and other structures. In addition, when the disease risk warrants it, truck and aerial ULV applications should be utilized to reduce the adult mosquito population. When combined with our larvicide efforts, these methods have proven highly effective at significantly reducing local populations of the target mosquitoes.
VDCI is a company built on the foundations of public health, ethics, professionalism, and technical expertise. We establish vector management programs that are based on an understanding of the underlying vector’s ecology and rooted in the current science of environmentally sound control measures.