Dengue fever is a mosquito-borne illness and a common cause of fever among travelers returning from tropical or sub-tropical climates. What should you know before you travel, and how severe can this illness be? Let's delve into these critical questions to ensure a safer and more informed travel experience.
What is dengue fever?
Dengue fever is a travel-associated illness caused by an arthropod-borne virus (or arbovirus). The virus is primarily transmitted by Aedes mosquitoes in tropical or sub-tropical areas where dengue is endemic (prevalent in a particular area).
Although it is the most common arboviral (caused by insect bites) disease worldwide, no vaccination is recommended for people traveling to areas where dengue is common. The FDA has not yet approved a dengue vaccine for travelers.
As dengue fever becomes more common, travelers should expect to see more cases. The highest number of cases in the last decade was in 2019. Areas where dengue fever has been common in recent years include Central and South America, Mexico, and the Caribbean.
What are the symptoms of dengue fever?
Most people have very mild or no symptoms of dengue infection and get better in 1–2 weeks. However, some individuals may experience high fever, headaches, body aches, nausea, and a rash.
Doctors treating travelers with a fever should be alert for dengue symptoms because early treatment can greatly reduce the risk of serious complications. With appropriate hydration and fluid management, the risk of death is generally less than 1%.
Is the dengue virus contagious?
The virus is not contagious from human to human because it is spread by infected mosquitoes. Mosquitoes that feed on a human who already has the dengue virus in their bloodstream become infected. The mosquito then goes through an incubation period where the virus travels from the mosquito's mid-gut to other tissues, such as the salivary glands. Once the mosquito is infected, it can pass on the dengue virus to other humans for the rest of its life.
Is dengue deadly?
As mentioned before, the risk of death is generally low, unless the infected person is not given prompt treatment to maintain fluids and control pain. People who have had dengue virus before are at high risk for more serious infection. For those who have antibodies to dengue, a vaccine may be given if they live in an endemic area.
Although most people recover well at home, approximately 1 in 20 people may develop a more severe illness. Symptoms of disease progression appear 1–2 days after the fever goes away. If any of these symptoms appear, they are a medical emergency, and the person should be seen by a medical professional right away:
- Stomach pain
- Bleeding from nose or gums
- Vomiting blood or passing blood in the stool
- Feeling tired or irritable
- Cold or clammy skin
- Difficulty breathing
What is the treatment for dengue virus?
The dengue virus can be managed at home with pain control and good fluid intake. Pain should be managed with acetaminophen (Tylenol). Non-steroidal anti-inflammatories (such as ibuprofen) and aspirin are not recommended because they may increase the risk of internal bleeding. Nonetheless, self-medication is not encouraged and should be observed by a medical expert.
What to know if you're traveling to Brazil: safety tips
If you are traveling to Brazil for the Carnival festival from February 9 through 17, prevent mosquito bites by taking common-sense precautions. The mosquitoes that spread dengue tend to bite more often during the day than at night, so health officials recommend the following steps:
- Wear loose-fitting clothing with long sleeves and pants.
- Use an Environmental Protection Agency registered insect repellant.
- Spray the mosquito netting around the sleeping area or bed with a repellent.
- Stay in a hotel with air conditioning or window screens.
Can I bring this disease back to my family?
Symptoms generally appear between 4 and 14 days after being bitten by a dengue-infected mosquito. You should be alert for symptoms after returning home from travel so that you can take care of yourself at home and recover. During the initial week of infection, the dengue virus circulates in the bloodstream, increasing the risk of transmission through mosquito bites. Therefore, it's essential to take precautions to prevent mosquito bites, especially indoors, particularly when caring for someone with dengue fever.
Should I get vaccinated before traveling?
There is no vaccine to prevent dengue fever because the currently available vaccine (Dengvaxia) is licensed only for those ages 6–16 who have had a previous laboratory-confirmed case of dengue and live in an endemic area.
The vaccine is limited to those with a previous infection because of a phenomenon called antibody-dependent enhancement (ADE), which means the vaccine makes subsequent infection worse instead of offering protection.
There are four known serotypes of dengue. When a person has antibodies to one serotype through prior infection or vaccination, the body is primed to allow the second serotype of the virus easier access to enter the target cells, causing more severe infection. However, the disease is usually milder if bitten again with a different version of the virus.
This complex interaction between exposure and protection makes it difficult to sort out who would benefit from vaccination. If vaccination is given to someone with no prior infection, then the vaccine might make the first infection worse.
However, if a person already has antibodies from a previous infection, then vaccination might prevent a more severe illness if bitten again. This is why vaccination is only recommended for those with prior infection who live in an endemic area, where the odds of another infection are higher.
Should I cancel my trip?
Whether or not to cancel your trip, for the Brazil festival or any other opportunity to travel in areas where dengue is endemic, is a personal decision based on your own risk tolerance. Remember that most people have no symptoms or only mild symptoms, and that with proper treatment the fatality rate is very low.
Are you willing to take precautions to reduce your risk? Do you plan to get medical care when you return home if you develop a fever, headache, or muscle aches? These are some of the aspects to consider.
What should I be aware of if I am already in Brazil?
If you are already in Brazil, take sensible precautions to avoid mosquito bites and enjoy your trip. Constant anxiety is not helpful for your immune system. Eat well, hydrate, stay moving, avoid napping outside without protection during the day, and remember that your body is well prepared to detect and contain any virus or bacteria you encounter.
Use your time in Brazil to learn how people are paying more attention to reducing processed foods and eating more fiber. The Brazilian government introduced new dietary guidelines in 2015 to help Brazilians eat more healthily. Instead of focusing on specific nutrients and complicated pyramids, the Brazilian guidelines encourage cooking whole foods at home, using sugar, fats, and salt in moderation, and appreciating the social benefits of eating together.
Ultimately, dengue fever, like any illness, is usually mild and can be treated at home. In the event that symptoms continue or worsen after the fever goes away, you should seek medical attention immediately to provide supportive care, such as fluid and pain management. To reduce the risk of contracting a mosquito-borne illness while traveling, take precautions to avoid being bitten, such as wearing loose-fitting long sleeves and pants, using an insect repellent, sleeping with netting, or staying in a hotel with air conditioning and screens on the windows.
Before your trip, get in the habit of improving your health every day so that you have the maximum likelihood of enjoying all the opportunities that travel presents and optimize your overall health.
Dengue fever, a prevalent illness in tropical and sub-tropical regions, is transmitted by infected mosquitoes and poses a significant health risk to travelers, especially in areas where it's endemic. Despite its common occurrence, there is currently no FDA-approved vaccine for travelers to protect against dengue fever.
While most cases of dengue fever result in mild symptoms or no symptoms at all, early recognition of symptoms and prompt medical attention can significantly reduce the risk of severe complications. Travelers should be aware of potential symptoms such as high fever, headaches, body aches, nausea, and a rash.
The decision to travel to regions where dengue fever is prevalent, such as Brazil during events like the Carnival festival, is a personal one and should consider individual risk tolerance and willingness to take precautions against mosquito bites. While the disease is typically manageable, travelers should prioritize preventive measures and be vigilant for symptoms both during and after their trip.
- CDC. Travel-associated dengue cases — United States, 2010–2021.
- WHO. Dengue and severe dengue.
- EPA. Find the repellent that is right for you.
- FDA. Dengvaxia.
- The Lancet Infectious Diseases. The dengue vaccine dilemma.