What Is Dengue Fever and Is It More or Less Dangerous Than Zika Virus?

The recent outbreak has Hawaii in a state of emergency. Here's what you need to know about the mosquito-borne disease.

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Because mosquitoes weren't pesky enough, now they're swarming all over our headlines, too.

On February 8, Mayor William Kenoi of Hawaii County declared a state of emergency on Hawaii's Big Island over an outbreak of the mosquito-borne dengue (pronounced den-gee) fever. As of February 16, the total number of confirmed cases of dengue fever in Hawaii is 256; 232 are island residents and 24 are visitors.

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According to the Centers for Disease Control and Prevention (CDC), as many as 400 million people are infected with dengue yearly. It rarely occurs in the continental United States but is regularly found in Puerto Rico and tourist locations in Latin America, Southeast Asia, and the Pacific Islands.

How Do You Get Dengue Fever?

Dengue can only be spread through infected mosquitoes, not from human to human. The Aedes aegypti (the same mosquito that carries Zika virus) is the main carrier of dengue.

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What Are Signs and Symptoms of Dengue?

There are four distinct but similar dengue viruses, which are referred to as dengue 1, 2, 3 and 4, says Stan Cope, PhD, president of the American Mosquito Control Association and director of entomology and regulatory services for Terminix®. "And you can be made by sick by all of those," he explains. "In other words, infection with one virus does not prevent you from getting infected by the other three because they are that different."

Symptoms of dengue fever typically appear about a week after being bitten by an infected mosquito. In many cases, it can be a fairly mild illness — headache, fever, abdominal pain, joint and muscle pain, and possibly a rash — and in some ways can mimic Zika virus. However, two characteristics of dengue fever are quite different from Zika.

"In a certain percentage of cases — and we don't really know exactly for sure why this is — patients develop hemorrhagic form, called Dengue Hemorrhagic Fever (DHF), and they can literally do what we call 'bleed out,'" Dr. Cope says. "They bleed from their mouth, ears, or nose. And unfortunately, many times it happens with children."

DHF usually begins with a fever that lasts between two and seven days in addition to the regular dengue fever symptoms mentioned above.

Cope continues that those infected with the most severe form of dengue may also suffer from excruciating muscle pain. "The nickname for dengue fever is 'breakbone fever,' so that should give you an idea as to how these patients feel," he explains. "They feel like their bones are literally breaking." Others may also experience retro-orbital pain, "which is pain behind the eyeballs."

Those who succumb to this illness will suffer from Dengue Shock Syndrome, which "means the person has lost so much blood, they go into shock. And by then, it's pretty much too late."

Dengue vs. Zika: Which One is More Dangerous?

DHF can be fatal if it goes unrecognized and isn't treated soon enough. An estimated 500,000 people with severe dengue require hospitalization each year, and about 2.5 percent of those affected die, according to the World Health Organization (WHO). If DHF is caught and treated with fluid replacement therapy early enough, the mortality rate can be less than 1 percent, according to the CDC

"The Zika virus doesn't cause fatality, as far as we know," Cope adds; however, Brazil's health ministry suspects three recent deaths may be linked to Zika. More research is needed to understand how Zika affects human health, including the its link to microcephaly in babies (a birth defect resulting in a small head and underdeveloped brain) and Guillain-Barré syndrome, which causes temporary paralysis.

"So to say that one is more dangerous than the other — I guess it depends on your point of view."

How Do You Prevent and Treat Dengue Fever?

Like many of these mosquito-borne viruses, there is no vaccine, "although people are working on it," Cope says. "And much like with Zika, the treatment is what we call supportive: Get plenty of rest, drink lots of fluids, and take acetaminophen for fever and pain."

As for keeping the infected biters at bay, Cope stresses two important tips: personal protection (which includes using repellents) and source reduction, which means eliminating the places where mosquitoes can live and breed.

"These mosquitoes grow up in water and are around artificial containers, like bird baths, children's toys, and tarps," he explains. "The adult mosquitoes, both males and females, will only fly about 100 yards from their breeding sites. So if you clean them out of your yard, they're not likely to re-invade your yard because they just don't go far away from where they 'grew up.'"

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