Why did travel-associated Dengue cases increase in the United States in 2019?
In 2019, the United States saw a sharp spike in travel-associated dengue cases. According to CDC surveillance data, 1,474 cases were reported that year — that's 168% higher than the average of about 550 cases per year during 2010-2018 and 2020-2021 910. This increase was not just due to more people traveling; the rate of cases per million trips to dengue-risk areas was also highest in 2019, at 41.9 cases per million trips compared to 21.0 in other years 910. The main reason is that dengue transmission was very high in many popular travel destinations that year, putting U.S. travelers at greater risk.
What the research says
Dengue is the leading cause of arboviral disease worldwide, and its global incidence has been rising due to factors like climate change, urbanization, and population growth, which expand the habitats of the mosquitoes that spread the virus 19. In 2019, many countries in the Caribbean, Central America, South America, and Asia experienced large dengue outbreaks. For example, Peru reported a notable increase in dengue cases in 2023 3, and Puerto Rico declared a public health emergency in 2024 4, illustrating ongoing risk in the region. U.S. travelers visiting these areas were more likely to be bitten by an infected mosquito and bring the virus back home 910. The CDC's ArboNet surveillance system tracks these cases, and the data show that 2019 was an outlier compared to the surrounding years 56910. Health officials note that as global temperatures rise and suitable mosquito habitats expand, the risk for U.S. travelers is expected to continue increasing 910.
What to ask your doctor
- What are the common symptoms of dengue I should watch for after returning from travel?
- If I develop a fever within two weeks of returning from a dengue-risk area, when should I seek medical care?
- Are there any blood tests you recommend to check for dengue if I have symptoms?
- How can I protect myself from mosquito bites when traveling to areas with dengue outbreaks?
- Should I consider any travel health precautions or vaccines before visiting dengue-endemic countries?
This question is drawn from common patient questions about Infectious Disease and answered using cited medical research. We do not provide individualized advice.