An Arizona resident recently contracted the mosquito-borne disease known as dengue, and the dengue virus has been detected in mosquitoes in the area. Dengue, normally associated with tropical countries, may be spreading in Arizona for the first time.
It’s not the first time dengue has shown up in the United States, but we don’t usually get local transmission of the disease in the 48 contiguous states. Florida has had at least three local cases of dengue this year, and has had several local outbreaks in recent years, with the largest being 66 cases in 2010. (Before 2009, there had been no cases since 1934, Outbreak News Today reports.) Dengue is common in several U.S. territories, including Puerto Rico, American Samoa, and the U.S. Virgin Islands.
So how big a deal is dengue, and what should you know about it? Let’s look at the facts.
How bad is dengue?
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About 75% of people who are infected with dengue won’t have noticeable symptoms. Statistically, 25% will get sick, 5% will get severe dengue, and 0.01% die from it.
It’s worth noting that you’re more likely to get severe dengue if you have had dengue before. There are four types of the dengue virus, so in theory you can get it four times in your life. But if you’ve had one type, and then contract another, that second infection carries a higher risk than the first of progressing to severe dengue.
Symptoms of an ordinary dengue infection may include nausea, vomiting, a rash, or muscle or joint pain. There may be a sensation of pain behind the eyes. The illness typically lasts between two and seven days. During this time, the CDC says, you should rest and you may take acetaminophen (Tylenol), but not aspirin or ibuprofen.
Symptoms of severe dengue can include belly pain or tenderness, bleeding from the nose or gums, blood in the vomit or stool, vomiting more than three times in 24 hours, or feeling unusually tired or irritable. If you have these signs, seek medical care right away.
How does dengue spread?
Dengue is caused by a virus, and that virus is transmitted by mosquitoes. Not all mosquitoes can transmit it, though. It requires Aedes aegypti or Aedes albopictus mosquitoes. These mosquitoes bite during the day as well as at night, and they can breed in small containers of standing water. Both species are more common in the southern U.S. than in northern areas.
(The little brown mosquitoes that live in more northern areas and bite more often at night are Culex mosquitoes, which do not transmit dengue. They can transmit West Nile virus, though.)
For a mosquito to give you dengue, it would have to bite someone with dengue, and then later bite you. If this happens in a given area, it’s considered local transmission of dengue. People can contract dengue while traveling and then bring it home, which accounts for most cases of dengue in the continental U.S.
How to avoid getting dengue
The main way to protect yourself from dengue is by protecting yourself from mosquito bites, and you can also help to protect your community by making sure the mosquitoes don’t have places to breed.
Mosquitoes will lay their eggs in stagnant water. This can include items like garbage cans and tires that fill with rain water, sources of water like dog bowls and birdbaths, and puddles that form on the ground or in tarps. Drain these items regularly if you can’t prevent them from filling up in the first place. (For example, if your dog has an outdoor water dish, make sure to empty it twice a week.)
To protect yourself from bites, the CDC recommends using an effective insect repellent (such as one containing DEET), wearing long-sleeved shirts and long pants where possible, and using window screens to keep mosquitoes out of the home.
There is a vaccine against dengue that is currently approved for children aged 9 to 16 who live in areas where dengue is common. It is not approved for people who are just traveling to those places.