No cases of the mosquito-borne Zika virus infection have been reported in North Carolina, and the mosquito that most often carries the virus is not commonly found in the state. But just in case, Mecklenburg County health officials are planning an extra effort this spring to control the spread of mosquitoes.
“People are very anxious about this,” said Dr. Marcus Plescia, Mecklenburg health director. “Our concern is that we could potentially get to the point where we have mosquitoes carrying the Zika virus here.”
In recent months, the virus has spread to 26 countries and territories in South America, the Caribbean and Central America, but not to the United States. The more than 50 U.S. cases of Zika virus are in people who had traveled to affected areas. In Brazil, the virus has been associated with a sudden surge in babies born with microcephaly, which causes unusually small heads and damaged brains.
Now’s not the time to worry (about mosquitoes). Generally, it’s early to mid-May, once it starts getting 70 every day or higher and not getting very cold at night.
Tim Dutcher, Mecklenburg County’s environmental health supervisor in charge of mosquito control
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In Mecklenburg, health officials say they’ve begun getting calls from “people who are worried” about mosquito transmission, said Tim Dutcher, environmental health supervisor in charge of mosquito control.
He advises them to get rid of standing water in gutters, bird baths, flower pots and other receptacles. But he adds that mosquitoes aren’t yet much of a problem.
“Now’s not the time to worry,” he said. “Generally, it’s early to mid-May, once it starts getting 70 every day or higher and not getting very cold at night.”
Every spring, the health department hires about 10 temporary employees to help with mosquito control. But this year, Dutcher and Plescia said they’ll hire extra workers to help respond to citizen complaints about standing water.
Two types of mosquitoes are known to transmit the Zika virus – Aedes aegypti and Aedes albopictus. The first, which most commonly transmits Zika, has a limited presence in North Carolina, in the southeastern corner. The second type, which less commonly carries Zika, is more common in the state.
In most years, they handle 200 to 300 complaints, but in 2015, because of the drought, the number was down to about 80. “It was the slowest year ever that I know of,” Dutcher said.
Mecklenburg officials do not spray with pesticides for adult mosquitoes, but they do routinely survey more than 1,300 sites in the county that have been identified as having significant mosquito breeding activity. If mosquito larvae are present, the water is treated with a larvicide to kill them before they hatch.
Plescia said the budget for mosquito control has “stayed pretty stable” at about $160,000 a year for the past 10 years. That’s despite the legislature’s decision to eliminate state funds to help with local mosquito control in 2014. Mecklenburg had received about $4,000 annually from the state, but county commissioners made up the difference, Dutcher said.
Two types of mosquitoes are known to transmit the Zika virus – Aedes aegypti and Aedes albopictus. The first, which most commonly transmits Zika, has a limited presence in southeastern North Carolina. The second type, which less commonly carries Zika, is more common in the state.
“Right now there’s not an imminent risk for anybody who’s not traveling,” Plescia said.
Even if the virus does reach the United States, he said it’s less likely to spread as quickly as it has in other countries because of better mosquito control and the widespread use of air conditioning and screens in windows and doors.
Still, news from Brazil about the virus’ potentially causing birth defects has raised concerns. Dr. Randall Williams, an obstetrician and state health director, said doctors across the state are getting calls from women who are pregnant or worried about becoming pregnant.
He refers them to guidelines from the U.S. Centers for Disease Control and Prevention, which advise pregnant women to avoid traveling to countries with active outbreaks and advise other women traveling there to use birth control.
Zika virus typically causes only mild illness, or sometimes no symptoms at all. But it has been associated with a complication called Guillain-Barre syndrome. Statistics show that the flu, West Nile virus and dengue fever (spread by the same mosquito as Zika) are far more deadly and dangerous.
At UNC Charlotte, Daniel Janies is among a network of scientists who have tracked the Zika virus around the world. It was first recorded in Uganda in 1947 and circulated through Africa, and jumped to Malaysia in 1966. It hopped across the Pacific Ocean in 2013 and arrived in the Caribbean in late 2014 and Brazil in mid-2015.
Transmission most likely occurred through infected travelers and through the worldwide trade in retreaded tires that can carry enough water to breed mosquitoes, Janies said. “That’s how we get these Asian and African mosquitoes spreading into new areas. It’s not a swarm of mosquitoes going across the Pacific.”