What is dengue fever? What to know as virus cases are confirmed in Florida

Eleven cases of dengue virus have been confirmed in Florida, prompting questions about the mosquito-borne illness. According to the Florida Department of Health, Broward County reported two cases and Miami-Dade reported nine cases. 

While the dengue virus typically comes from places outside of Florida, one of the cases in Miami-Dade reported last week was locally acquired, CBS News Miami reports. 

Almost half of the world's population live in areas with dengue risk, according to the Centers for Disease Control and Prevention. The virus is often a leading cause of illness in these areas, primarily in tropical and sub-tropical climates around the world.

"Each year, up to 400 million people are infected by a dengue virus," the CDC's website says. "Approximately 100 million people get sick from infection, and 40,000 die from severe dengue."

What is dengue fever?

Dengue virus, often referred to as dengue fever or "break-bone fever," due to pain being one of the major symptoms, is spread to humans through the bite of an infected mosquito.

Many people don't develop any symptoms, while others get a relatively mild case the of illness that typically gets better in 1 to 2 weeks, according to the World Health Organization. For some, however, the infection can evolve to severe dengue, which is a medical emergency that may require hospital care. 

• Related: What is malaria? What to know as Florida, Texas see first locally acquired infections in 20 years

Dengue symptoms

About 1 in 4 people infected with dengue will get sick, the CDC says, with symptoms ranging from mild to extreme. About 1 in 20 people who get sick will develop severe dengue, which can result in shock, internal bleeding and even death.

The most common symptom? Fever, which is usually accompanied by the following:

• Nausea and vomiting
• Rash
• Aches and pains, including pain behind the eyes

If symptoms occur, they usually start 4 to 10 days after infection and last for 2 to 7 days, according to the WHO.

Additional warning signs that could point to severe dengue include: 

• Belly pain, tenderness
• Vomiting (at least 3 times in 24 hours)
• Bleeding from the nose or gums
• Vomiting blood, or blood in the stool
• Feeling tired, restless or irritable

"Immediately go to a local clinic or emergency room" if you or a family member has any of those symptoms, the CDC says. "Warning signs usually begin in the 24 to 48 hours after your fever has gone away."

Dengue treatment

There is no a specific medicine to treat dengue fever. Most cases can be treated at home with pain medicine like acetaminophen to manage symptoms, the WHO says.

There is a vaccine called Dengvaxia for some people who have previously had dengue and live in a high-risk area.

Dengvaxia is the "only dengue vaccine approved by the U.S. Food and Drug Administration and recommended for routine use by the Advisory Committee on Immunization Practices," the CDC notes. It became available in 2022 for children and adolescents ages 9 to 16 in "dengue-endemic areas" which include American Samoa, Puerto Rico, and the U.S. Virgin Islands.

The best way to avoid getting dengue, however, is through preventing mosquito bites.

To prevent bites, experts advise using insect repellent and wearing loose-fitting, long-sleeved shirts and pants. The CDC and WHO recommend insect repellents with active ingredients that include:

• DEET
• IR3535
• Oil of lemon eucalyptus (OLE)
• Picaridin (KBR 3023)

CBS Miami notes some repellents are not suitable for young children: DEET is not recommended for children younger than 2 months old, while lemon eucalyptus oil should not be used on children under 3 years old.

Experts also advise clearing out standing water around your home or yard where mosquitoes might lay their eggs.

• Research found these mosquito repellents are the most effective ways to get rid of the pests

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• Dengue fever