Dengue cases are rising worldwide. What it means for Georgia

The CDC urges doctors to remain alert for symptoms and ask patients about recent travel as cases rise worldwide.

Experts say Georgia residents should take precautions against mosquito bites, but they stress that dengue is unlikely to spread here. Georgia residents are much more at risk of contracting West Nile virus, which caused 81 infections in the state between 2018 and 2022.

Dengue is the most common mosquito-borne infection worldwide, but in the U.S., most dengue cases are associated with travel to tropical and subtropical locations, such as the Virgin Islands, Puerto Rico, and South America. So far this year, there have been nearly 1,500 locally acquired cases of dengue in the U.S., almost all of them in Puerto Rico.

Mosquito-borne diseases are transmitted to humans through the bites of infected mosquitoes. They are not transmitted from person to person.

Dengue fever is mainly spread by the bite of the infected Aedes aegypti or yellow fever mosquito, a type of mosquito that is very rare in Georgia. However, the Aedes albopictus or Asian tiger mosquito — which is very common in Georgia — has been shown to transmit dengue fever in other places outside Georgia.

According to experts, Georgians are at greater risk of contracting dengue when traveling.

Gonzalo Vazquez-Prokopec, an expert in vector ecology and control in Emory’s Department of Environmental Sciences, said the increase in dengue cases is being fueled by high temperatures resulting from last year’s El Niño, a climate pattern characterized by warmer-than-average ocean temperatures.

A post-pandemic travel boom is also playing a role in the rebound. “Human mobility, both short and long distance, plays a major role in moving viruses,” he said.

If a mosquito bites someone infected with dengue, it can transmit the virus to other people. This means that local outbreaks are possible when people import the virus.

However, because the number of travelers in Georgia who become infected with dengue is so small, the chance of the disease spreading locally in Georgia is very small. This is mainly because the type of mosquito (Aedes aegypti) that spreads dengue is rare in Georgia.

Gonzalo Vazquez-Prokopec, an expert in vector ecology and control in Emory's Department of Environmental Sciences. Photo taken on Emory's campus. Stephen Nowland/Emory University

Photo: Steve Nowland

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Photo: Steve Nowland

There is no specific medicine to treat dengue. There are also no vaccines for adults or people who have never had dengue before.

Only one in four dengue cases has symptoms. While some infections cause only mild symptoms, others can cause headaches, high fever, aching joints, and weeks of recovery. About 5% of people infected with dengue will have severe dengue, which can lead to shock, internal bleeding, organ failure, and even death.

Vazquez-Prokopec said precautions should be taken to avoid mosquito bites for those traveling to places where dengue is spreading, and travelers should also take steps to avoid being bitten when they return home. Many people infected with dengue do not experience any symptoms and do not even know they have it.

Elmer Gray, an entomologist with the University of Georgia Cooperative Extension Service, said features taken for granted in higher-income countries help reduce and prevent exposure to disease-carrying mosquitoes and can help prevent continued spread. Air conditioning, window screens and drainage systems all reduce mosquito breeding and exposure.

Malaria, once a common disease in the U.S., was eradicated in the early 1950s through the use of insecticides, drainage ditches and screens. The last locally acquired malaria case in Georgia dates back at least two decades to a probable case in 1999, according to the DPH. In Florida, there were seven cases of locally acquired malaria last year.

Gray, a public health specialist whose research focuses on mosquitoes and other insects such as blackflies, said West Nile virus, a virus spread locally by mosquitoes in Georgia, continues to pose a threat to Georgia residents. He said there were 19 cases of West Nile virus in Georgia last year, and two of those cases died from complications of the virus. There have been no human cases reported this year, but it’s still early, as the season typically peaks in August and September.

West Nile is most commonly transmitted in Georgia by the southern house mosquito, which is common throughout the state. In most cases, a healthy immune system can fight off West Nile. But in rare cases — usually in the elderly, people with weakened immune systems, or very young children — the disease can develop and cause symptoms such as fever and rash. In extremely rare cases, the virus can lead to encephalitis (swelling of the brain) and death.

Eastern Equine Encephalitis (EEE) is another mosquito-borne disease that has emerged in Georgia. It is extremely rare with four cases in the state between the years 2018 and 2002. Mosquito species known to transmit EEE are primarily found in coastal marshy areas of the state.

Georgia is home to 63 species of mosquitoes. And when it comes to combating mosquitoes of all kinds, vigilance is key, experts say.

How bad mosquitoes will fare in metro Atlanta this summer remains to be seen. Mosquitoes love warmth, but they also need standing water to complete their life cycle. This dry spell of scorching temperatures means a decline in the overall mosquito population, especially those that prefer warm, wet conditions.

But weather conditions can change quickly.

“So here we are in July with people going outside at dusk, when most mosquitoes are active,” Gray said. “If we’re having trouble with pesky mosquitoes in metro Atlanta, it’s because something is missing. There’s a dumpster, there’s an abandoned pool, there’s a tire (of standing water). Take some precautions. Light-colored, loose-fitting clothing, EPA-approved repellents. A few precautions can go a long way.”

Tips to prevent mosquito bites:

1. Wear light-colored clothing. Mosquitoes are more attracted to people who wear dark colors because they stand out more.

2. When outdoors in a mosquito-prone area, insect repellent is the most effective step. There are several commercially available, EPA-approved insect repellents, such as picaridin, lemon eucalyptus oil, and IR3535. Gray prefers products that contain DEET because they have been tested and found to be safe for children as young as 2 months old. When treating children, an adult should apply the repellent to his or her hands first and then rub it into the child’s exposed skin, but never onto a child’s hands, as young children have a habit of putting their hands in their mouths.

3. Mosquitoes need standing water to breed. Therefore, eliminate sources of standing water in gardens and landscapes.

4. Keep the grass short and prune the vegetation around the edges of the garden to reduce the number of places for adult mosquitoes to hide during the heat of the day.

5. Mosquitoes are most active at dawn and dusk, so stay indoors to avoid being bitten.

6. If you are sitting on your porch or patio, you can use a fan to repel mosquitoes.

Source: Elmer Gray, entomologist with University of Georgia Cooperative Extension Service

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