Health

West Nile cases in mosquitoes on the rise in metro Atlanta

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On a scorching summer afternoon, Callie Pierce, wearing jeans, red T-shirt, and closed-toe shoes (along with plenty of bug spray), checks on a mosquito surveillance trap along the edge of Brookside Park in DeKalb County.

Callie Pierce, a seasonal staff member at the DeKalb County Health Department’s Division of Environmental Health, checks a mosquito trap at Brookside Park. The mosquitoes in the trap were removed for testing. After stretches of heavy rains, mosquitoes tend to multiply, and this year testing is showing an unusually high number of mosquitoes testing positive for West Nile virus. BOB ANDRES / BANDRES@AJC.COM
(The Atlanta Journal-Constitution)

Dozens of mosquitoes, fluttering inside a plastic container, will soon be shipped to a lab and be tested for West Nile virus.

It’s difficult to predict the timing and magnitude of West Nile virus outbreaks. But conditions could be ripe this year for an uptick in the mosquito-borne illness, which can cause aches, fever and in rare cases, death.

Last year, Georgia saw an increase in West Nile virus cases — 47 human cases, including seven deaths, according to the Georgia Department of Public Health. That’s up from seven human cases and no confirmed deaths related to West Nile virus in 2016.

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Discarded rubbish, like these bottles and cans found in a culvert, can contain enough water for mosquitoes to breed. After stretches of heavy rains, mosquitoes tend to multiply, and this year testing is showing an unusually high number of mosquitoes testing positive for West Nile virus. BOB ANDRES / BANDRES@AJC.COM
(The Atlanta Journal-Constitution)

Local and state health officials aren’t suggesting families drop plans for football games or backyard barbecues, but they are emphasizing it’s increasingly important to take steps to be protected from mosquitoes. Removing standing water from breeding sites such as garden containers and clogged gutters, limiting time outdoors at dawn and dusk and wearing long sleeves and long pants can help prevent bites from the outdoor pests.

Callie Pierce, a seasonal staff member at the DeKalb County Health Department’s Division of Environmental Health, checks a mosquito trap at Brookside Park. BOB ANDRES / BANDRES@AJC.COM
(The Atlanta Journal-Constitution)

The Atlanta Journal-Constitution was given permission to join DeKalb County workers as they took steps to test and control mosquito populations. At Brookside Park, Pierce, a student at Agnes Scott College and seasonal worker with the DeKalb County Division of Environmental Health, leaned down to pick up the sizable capture of blood-sucking insects lured into the trap by a concoction mosquitoes can’t resist — stagnant water, hay and brewer’s yeast.

The number of mosquitoes testing positive for West Nile virus has been steadily rising this summer. In DeKalb County, for the week ending Aug. 7, 23 percent of the mosquito collections tested positive for the virus, up from 13 percent in 2017, and 3 percent in 2016 during that same week.

Live mosquitoes, after they have been chilled, are sorted at the DeKalb County Health Department’s Division of Environmental Health. The types that can carry the West Nile virus will be sent for testing. BOB ANDRES / BANDRES@AJC.COM
(The Atlanta Journal-Constitution)

Georgia Department of Health spokesperson Nancy Nydam said other mosquito pools in other parts of the state have also tested positive for West Nile virus. There have been two human cases of West Nile virus in Georgia already this season. Human cases of West Nile virus tend to peak in late August and September.

As Gordon Cargal, Environmental Health county supervisor for the DeKalb County Board of Health, checked on the surveillance trap set up at Brookside Park, he didn’t seem surprised by the swarm of mosquitoes drawn to the trap.

“Mosquitoes are everywhere,” he said. “We are in the South.”

People typically get West Nile virus from the bite of a mosquito that has fed on an infected bird. Most people infected with West Nile virus don’t have any symptoms. About 1 in 5 people who are infected develop a fever and other symptoms such as a rash and fatigue. About 1 out of 150 infected people develop a serious, sometimes fatal, illness. There is no vaccine to prevent infection, and there are no antiviral medications to treat the virus.

A total of 40 states and the District of Columbia have reported West Nile virus infections in people, birds or mosquitoes as of Aug. 7, according to the Centers for Disease Control and Prevention.

Georgia is home to 63 mosquito species. West Nile is most often carried in Georgia by the Southern house mosquito. These mosquitoes like it dry or when there’s a little rain or little pools of water left over after rain. They hang out in storm drains and/or pockets of water. When it rains a lot, you are less likely to see West Nile cases because frequent rains wash the mosquito larvae out of the storm drains.

West Nile virus, which arrived in New York City in 1999, now appears unpredictably across the country. Georgia and other parts of the country, for example, saw a big outbreak in 2012. Most years, Georgia has fewer than 20 human cases of West Nile, but in 2012, there were 99 human cases in the state, and last year marked another rise in cases, according to the CDC. Experts aren’t sure why the numbers rise and fall, but weather patterns likely play a role.

Matthew Calhoun, an environmental health inspector from the DeKalb County Health Department’s Division of Environmental Health, drops a larvicide briquette into one of the storm drains at Brookside Park to help control mosquitoes. BOB ANDRES / BANDRES@AJC.COM
(The Atlanta Journal-Constitution)

Meanwhile, back in DeKalb County, mosquito control efforts include treating over 4,800 storm drains and other breeding sites with larvicide, and visiting more than 3,000 homes with information about mosquito prevention, along with ongoing surveillance at dozens of mosquito trap locations throughout the county. Other metro Atlanta counties, including Fulton County and Cobb County, maintain mosquito control programs, while Gwinnett County does not.

Mosquitoes are tested for West Nile and other viruses including Zika. Fortunately, there have been no cases of a mosquito in Georgia testing positive for Zika.

With mosquito season in full swing, experts say we can all help in preventing mosquito-borne illnesses by being vigilant — and it often starts in our backyards.

“People need to do a lot,” said Juanette Willis, arbovirus coordinator in the Division of Environmental Health at DeKalb County. “If you have mosquitoes in your backyard, they are breeding in your backyard. You need to get rid of standing water and make sure your yard is not a breeding ground. That means containers and toys but also places you might not think of, like magnolia leaves on the ground.”

TIPS FOR PREVENTING WEST NILE VIRUS

The most effective way to protect against West Nile infection and all mosquito-borne diseases is to prevent mosquito bites. Eliminating larval habitats, wherever possible, is the key to reducing mosquito populations. Here are five tips from Elmer Gray, an entomologist with University of Georgia Cooperative Extension.

1. Get rid of standing water. Mosquitoes need standing water to reproduce, so eliminate sources of standing water in yards and landscapes. Be on the lookout for abandoned planters and flowerpot saucers, mop buckets, toys, overturned Frisbees and anything else that can hold water. Larvicidal briquettes are available to treat water gardens, rain gardens, clogged drainage ditches or any other permanent landscape feature that holds water for more than a week.

2. Cut the grass. Keeping grass trimmed and the vegetation around the borders of the yards cut back can also help reduce the areas where adult mosquitoes hide during the heat of the day.

3.Limit time outdoors at dawn and dusk. Mosquitoes are most active at dawn and dusk, so people may want to stay inside during those times to avoid bites. Gray also recommends checking, repairing and replacing window screens at this time of year to keep mosquitoes from making their way inside.

4.Wear light-colored clothing. Mosquitoes are more attracted to people wearing darker colors because they stand out more, so go with khaki and other lighter shades to help keep mosquitoes at bay. Gray notes they’ve come a long way with more fashionable clothing to protect people from the sun and bugs.

5. Use bug spray. When outside in a mosquito-prone area — like on a ballfield, out in the yard or out in the woods, Gray said the most effective thing people can do to protect themselves is to use insect repellent. There are several commercially available, EPA-approved repellents, like picaridin, lemon eucalyptus oil and IR3535. Gray prefers products with DEET because they have been tested and proved safe for children as young as 2 months old.

A product with a 10 percent to 30 percent concentration is good and protects for several hours, Gray said. When treating children, an adult should apply the repellent to his or her hands first and then rub the repellent onto the child’s exposed skin, but never to a child’s hands. (Small children have a habit of sticking their hands in their mouths, and if they apply the repellent themselves, there’s a good chance they’ll ingest some of it, he added.)

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