Merck Manuals: What Travelers Need to Know About Dengue

RAHWAY, N.J., Oct. 10, 2024 /PRNewswire/ -- Dengue fever is a mosquito-borne viral infection that when mild, can cause flu-like symptoms. But in a more severe form, the virus can also lead to internal bleeding, organ damage, and death. For individuals living or traveling where dengue is common, there are important things to know to minimize your risk.

In a new editorial from MerckManuals.com, Thomas M. Yuill, PhD, University of Wisconsin-Madison, shares information and advice.

1. Not all mosquitoes carry dengue

Dengue is spread to people through the bites of infected Aedes species mosquitoes, says Yuill. Each year, about 50 to 100 million cases of dengue and about 20,000 deaths occur worldwide. However, in the United States, only about 100 to 200 cases occur annually, with nearly all brought in by travelers returning from other countries, says Yuill.

2. Dengue is spreading to new areas

Dengue is common in the tropics and subtropics worldwide. It is often found in Southeast Asia but has become more prevalent in recent years in Central and South America, including countries like Brazil.

At the same time, Aedes mosquitoes are turning up in new places due to human activity and a changing climate. In the United States, they've been found in states including Florida, Southern California, Texas, Arizona and the Midwest. A few cases of locally transmitted dengue have occurred in Hawaii, Florida and Texas.

3. Dengue comes in three phases

Dengue symptoms typically begin suddenly, causing fever, chills, a severe headache, pain when the eyes are moved, extreme fatigue and severe generalized body aches, particularly in the back, legs, and joints.

These symptoms typically last for a few days, after which patients begin to feel better for about 24 hours. "People may think they're out of the woods, but then the fever can return, along with more serious effects, including dengue hemorrhagic fever, bleeding and shock," says Yuill.

4. Dengue is not contagious

In a vast majority of instances, people with dengue cannot transmit it to others, says Yuill. A mosquito can transmit it by biting a person with an infection and then biting someone else. Although uncommon, a pregnant woman can pass the dengue virus to her fetus during pregnancy or around the time of birth.

5. There is currently no vaccine against new cases

The only dengue vaccine currently available in the United States is approved for children who have been previously infected and live in an area where the disease is common, says Yuill. There are a number of vaccines in development that can be used for individuals who have not had prior dengue infections as well as those who have.

6. Travelers need to take precautions

Anyone traveling to parts of the world where dengue is common should take steps to protect themselves and their fellow travelers.

"When traveling, the same best practices around avoiding all mosquito bites apply," says Yuill. Wear light-colored, long-sleeved, loose-fitting clothing. Use insect repellant. Some repellants are increasingly being added to sunscreens. Just be sure to check the labels before using any product on children.

7. Travelers should watch for symptoms

Symptoms of dengue typically begin about three to 15 days after being bitten by an infected mosquito. Often, a traveler only starts to feel sick after they return home. If you've traveled to an area where dengue is present and start to feel sick, it's essential to provide travel details when talking to your doctor, says Yuill.

To read more of Yuill's insights on dengue, visit this editorial on MerckManuals.com.

About The Merck Manuals and MSD Manuals

First published in 1899 as a small reference book for physicians and pharmacists, The Merck Manual grew in size and scope to become one of the world's most widely used comprehensive medical resources for professionals and consumers. As The Manual evolved, it continually expanded the reach and depth of its offerings to reflect the mission of providing the best medical information to a wide cross-section of users, including medical professionals and students, veterinarians and veterinary students, and consumers. In 2015, The Manuals kicked off Global Medical Knowledge 2020, a global initiative with the goal to make the best current medical information accessible by up to three billion professionals and patients around the world by 2020. The Manuals achieved that goal, and today its medical information is available in nearly 250 countries and in 14 languages. It's continuing its ambitious mission through outreach, education and creating new reliable medical resources. For access to thousands of medical topics with images, videos and a constantly expanding set of resources, visit MerckManuals.com or MSDManuals.com and connect with us on social media: For Consumers in the U.S. and its territories: X (formerly Twitter) and Facebook. For Professionals in the U.S. and its territories: X (formerly Twitter) and Facebook

About Merck

At Merck, known as MSD outside of the United States and Canada, we are unified around our purpose: We use the power of leading-edge science to save and improve lives around the world. For more than 130 years, we have brought hope to humanity through the development of important medicines and vaccines. We aspire to be the premier research-intensive biopharmaceutical company in the world – and today, we are at the forefront of research to deliver innovative health solutions that advance the prevention and treatment of diseases in people and animals. We foster a diverse and inclusive global workforce and operate responsibly every day to enable a safe, sustainable and healthy future for all people and communities. For more information, visit www.merck.com and connect with us on X (formerly Twitter), Facebook, Instagram, YouTube and LinkedIn.

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