Dengue Is Changing in the United States: What You Should Know
This article explains the recent dengue situation in simple language, including symptoms, warning signs, testing and ways used to control dengue.
What Happened in 2024?
According to the CDC data discussed in the research report, the United States reported 3,798 dengue cases in 2024. This was much higher than the average number of cases reported during 2010–2023.
2024 Dengue Cases at a Glance
| Epidemiological Measure | Number | Percentage |
|---|---|---|
| Total reported U.S. cases | 3,798 | 100.0% |
| Travel-associated cases | 3,693 | 97.2% |
| Locally acquired cases | 105 | 2.8% |
| Hospitalizations | 1,370 | 36.1% |
| Severe dengue cases | 105 | 2.8% |
| Fatalities | 6 | 0.2% |
Local Dengue Transmission
The research report describes increasing evidence of local dengue transmission in parts of the United States.
In Florida, 152 locally acquired cases were reported in 2026, including 134 cases in Hillsborough County. California also reported locally acquired dengue cases. In Los Angeles County, 14 locally acquired cases were identified in 2024 across six neighborhoods.
By 2026, Orange County had also reported its first human case of locally acquired dengue. The research report also describes detection of dengue-positive wild mosquitoes in Los Angeles County.
It means the infection was acquired locally rather than during travel to another country or area where dengue is circulating.
Why Can Dengue Spread?
Dengue is mainly spread by infected Aedes mosquitoes. Two important mosquito species mentioned in the research are:
- Aedes aegypti – commonly called the yellow fever mosquito.
- Aedes albopictus – commonly called the Asian tiger mosquito.
Temperature affects mosquito development and the ability of the dengue virus to develop inside the mosquito. The research identifies an optimum temperature range of about 25°C to 30°C for Aedes development and transmission.
Dengue Can Have Mild or No Symptoms
The research report notes that approximately 75% of dengue infections may be asymptomatic or produce only mild, non-specific illness. Because of this, some infections may not be recognized or reported.
Common Symptoms of Dengue
Dengue illness can begin several days after the bite of an infected mosquito. The research describes the following symptoms:
| Common Symptom | What a Person May Notice |
|---|---|
| High fever | Sudden or high temperature |
| Severe headache or pain behind the eyes | Strong headache or pain around/behind the eyes |
| Muscle and joint pain | Body aches and joint pain |
| Skin rash | A macular skin rash may appear |
| Nausea or vomiting | Feeling sick or vomiting |
| Mild bleeding signs | For example, small skin spots or nose bleeding |
Warning Signs: When Dengue May Become Severe
| Warning Sign |
|---|
| Intense and continuous abdominal pain or tenderness |
| Persistent vomiting |
| Fluid accumulation |
| Mucosal bleeding such as bleeding from the gums or nose |
| Enlargement of the liver |
| Lethargy, irritability or altered mental status |
| Increasing hematocrit together with a rapid fall in platelet count |
Warning signs are based on the CDC and WHO clinical guidelines cited in the research document.
Why Can a Second Dengue Infection Be More Serious?
There are four dengue virus serotypes: DENV-1, DENV-2, DENV-3 and DENV-4.
Infection with one serotype provides long-term immunity against that same serotype, but protection against the other serotypes is only partial and temporary.
The research discusses a phenomenon called Antibody-Dependent Enhancement (ADE). A second infection with a different serotype can increase the risk of severe disease in some people.
Dengue Serotypes Reported in 2024
Among 1,204 patients for whom serotype information was available, the distribution reported in the research was:
| Dengue Serotype | Percentage |
|---|---|
| DENV-3 | 54.8% |
| DENV-4 | 23.2% |
| DENV-1 | 12.5% |
| DENV-2 | 9.5% |
How Is Dengue Diagnosed?
The type of test used can depend on how many days have passed since symptoms began.
| Time Since Symptoms Began | Tests Discussed in the Research |
|---|---|
| 0–7 days | NAAT/RT-PCR with IgM, or NS1 antigen with IgM |
| After 7 days | Serological testing such as IgM and IgG |
The research also explains that dengue antibody tests can sometimes cross-react with antibodies related to other flaviviruses, including Zika virus and West Nile virus. This can make diagnosis more difficult.
How Can Dengue Be Controlled?
Because there is no specific antiviral treatment described in the research, dengue prevention depends greatly on surveillance and mosquito control.
The research discusses several approaches, including traditional mosquito control as well as newer methods such as Wolbachia-based mosquito control and genetically modified mosquitoes.
Wolbachia Mosquito Control
Wolbachia is a naturally occurring bacterium found in many insect species. Scientists can introduce Wolbachia into Aedes mosquitoes. The research explains that Wolbachia can interfere with the ability of dengue and some other viruses to replicate inside mosquitoes.
Two approaches described in the research are:
- Population replacement – Wolbachia-infected mosquitoes are released so that the bacteria become established in the mosquito population.
- Population suppression – Wolbachia-infected male mosquitoes are released to reduce the number of mosquitoes capable of reproducing.
Genetically Modified Mosquitoes
The research also describes genetically modified male mosquitoes developed to reduce populations of disease-carrying Aedes mosquitoes.
Field trials of the Oxitec OX5034 strain in targeted areas of Florida and California reportedly demonstrated substantial reductions in local Aedes aegypti populations.
What Should You Do If You Have Symptoms?
- If you develop symptoms that may be consistent with dengue, seek medical advice.
- Tell the healthcare provider about recent travel, if applicable.
- Follow the tests and medical advice recommended by the healthcare provider.
- If warning signs appear, seek medical care promptly.
Key Takeaways
| What to Remember | Simple Message |
|---|---|
| Dengue is mosquito-borne | Aedes mosquitoes can transmit dengue virus. |
| Travel remains important | Most reported U.S. cases in 2024 were travel-associated. |
| Local transmission is occurring | Locally acquired cases were reported in states including Florida, California and Texas. |
| Many infections are mild | Some people may have no symptoms or only mild illness. |
| Warning signs matter | Severe abdominal pain, persistent vomiting and bleeding are among the warning signs described in the research. |
| Mosquito control is important | Controlling Aedes mosquitoes is an important part of dengue prevention. |
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Sources
Original sources used in the research document include:
- Centers for Disease Control and Prevention (CDC), Morbidity and Mortality Weekly Report – Increase in Travel-Associated and Locally Acquired Dengue Cases.
- Centers for Disease Control and Prevention (CDC) – Dengue current-year data.
- World Health Organization (WHO) – Dengue and Severe Dengue.
- CDC – Clinical Care of Dengue.
- CDC – Dengue Clinical Testing and Diagnosis.
- CDC – Dengue Case Management guidance.
- Contagion Live – Reports on locally acquired dengue in Los Angeles County.
- Greater Los Angeles County Vector Control District – Detection of dengue-positive mosquitoes.
- Peer-reviewed research on asymptomatic dengue infection.
- Peer-reviewed research on temperature, mosquito transmission and dengue virus.
- World Mosquito Program – Wolbachia mosquito control approach.
- Research and reports concerning genetically modified mosquitoes and dengue vector control.
The information above is based on the sources and research document used to prepare this article.
This article is provided for general health awareness and educational purposes only. It is not a substitute for medical examination, diagnosis or treatment.
Symptoms can have many causes. If you have symptoms of dengue or any warning signs described in this article, contact your nearest health centre, doctor or hospital for appropriate medical advice.
Do not start, stop or change medicines based only on information from this article.
