Zika Taskforce Surveys State Mosquito Population
In response to the Zika outbreak, and any threat it may pose to North Carolinians, a statewide co-op of researchers, pest control specialists, and doctors are studying local mosquito populations – specifically, carriers of the headline grabbing virus.
The study is in its early stages, but as Chris Thomas reports, participants – and the state as a whole – may have gone into it with a hand tied behind their back.
Summertime in eastern North Carolina. It isn’t uncommon for temperatures to reach and surpass seasonal averages, accompanied by heavy, muggy air.
It’s the perfect conditions for mosquitoes to breed, thrive, and feed.
Dr. Stephanie Richards is an entomologist at East Carolina University.
“In coastal counties, we have problems with salt marsh mosquitoes so that those are more prevalent in those types of areas.”
It’s hard to stand up and say a good word for mosquitoes – even if they’re part of your work. Even Dr. Richards had to scramble to say something on their behalf – other than their place on the food chain (which is low).
“Male mosquitoes, they only feed on plant nectar, but in between blood feeding, the female mosquitoes do feed on plant nectar, so they could…play some role in pollination, I guess, if you’re searching for something [laughter].”
Mosquitoes have a knack for prolific breeding habits, making Tony Padgett’s work all the more frustrating. He is the director of the Onslow County Environmental Service Vector Control program.
But with the Zika virus receiving banner headlines throughout the year, he said it’s getting easier to convince homeowners to get rid of containers with standing water.
“Prime example – if you’ve got gutters on your home, and you don’t keep those gutters cleaned out – pine straw gets all up in there and it gets damp, but it’s a perfect breeding area for mosquitoes, especially the Asian Tiger, and that’s what you’re going to find. It’s a striped mosquito, pretty large mosquito that you’re gonna find around your home.”
Onslow County is a partner in a statewide study on Zika, led by East Carolina University, North Carolina State University, Western Carolina University, and the state Department of Health and Human Services. The collaboration, known as the Zika Taskforce, surveys the mosquito population across the state – taking special notice of Zika carriers.
Thus far, we know of two breeds that can carry the disease – the Asian Tiger and the “aedes aegypti.” The latter is the most common carrier of the Zika virus, but is far less prevalent in North Carolina.
“We’re confirming that aedes albopictus is ubiquitous throughout North Carolina and we’re definitely looking for aedes aegypti just in case that species pops up, that would be of concern for virus transmission.”
Mosquito samples are collected and sent to labs across the state. Six eastern partners – Onslow County, the Albemarle Health District, Camp Lejeune, New Hanover County, Brunswick County, and Pitt County – are participating in the taskforce.
According to the North Carolina Department of Health and Human Services, $2 million – through state funding and grants – will go toward researching and controlling the mosquito population. That includes grants for local participants in the Zika Taskforce.
“And it enabled us to buy, like, nine more light traps, which give us more surveillance around the county dead of what we got. We’ve got 14 light traps we constantly monitor every day, and we place them in different, strategic places to see that we’re covering everybody.”
Dr. Richards said the study hasn’t rendered any surprises thus far. Earlier this year, she and her students studied mosquitoes found in Greenville and observed a unanimous rate of infection and dissemination of Zika, but a low rate of transmission – somewhere between 10 and 20 percent, according to a release from the university.
Dr. Richards said the Zika sample came from a specimen found in Puerto Rico, where there have been more than 1,800 locally acquired cases.
She, like most experts, believes an outbreak in North Carolina is highly unlikely – due in part to a short window of opportunity.
“A person would have to travel to an area where Zika virus is endemic and then – there’s a period of time call the “viremic period” – for about a week after they’ve been bitten by an infected mosquito. That person may be able to infect other mosquitoes, should they travel back to our area, and our mosquitoes bite them.”
None the less, the Zika outbreak has caused a stir on the national and state level, especially after reports of the first North Carolina case surfaced in the winter. Though Zika’s symptoms aren’t as pronounced and other, vector-borne diseases (including West Nile and Dengue) – it has been linked to a birth defect, microcephaly, by several medical authorities, including the CDC.
That link touches an especially strong nerve for Dr. Randall Richards – an obstetrician and director of the North Carolina Department of Health and Human Services.
“We have 1,700 obstetricians in North Carolina. About 175,000 women get pregnant every year in North Carolina. So, we certainly knew that we needed to deal with that issue well before we would actually see any potential outbreaks in North Carolina.”
The Zika Taskforce brings back to light the elimination of North Carolina’s long-running mosquito control program five years ago. It happened via House Bill 200, the state’s biannual budget passed in 2011. Since then, funding for local mosquito prevention programs has been difficult to come by.
According to a March survey conducted by the taskforce, nearly half of the state’s 100 counties – including Bertie, Craven, and Duplin – do not have a mosquito control program and 14 counties – including Dare, Wilson, and Nash – only offer education resources for their residents.
The Department’s Public Health Veterinarian Dr. Carl Williams says North Carolina’s part of a large trend.
“And when you look at the number of them that have been functioning, they’ve been declining, really, ever since 2003, and that’s a feature that’s noted nationwide and that’s been published in the MMWR (The CDC’s Morbidity and Mortality Weekly Report) and that’s something that is of general concern to the CDC because states have been losing capacity, so we’re not unique in that regard.”
It’s made fighting and monitoring the mosquito population even harder in a state where both are of the utmost importance, Dr. Richards said.
“The medical entomologist from the Public Health, Pest Management, they were the connectors between the state and the local mosquito control entities, so we’re definitely missing that link.”
Onslow County’s amended budget for the last fiscal year allotted the program $487,877 – though their services also include keeping the county’s waterways clear throughout the year.
But, he says he feels optimistic about the state’s new efforts toward mosquito control. According to the state Department of Health and Human Services, the state allotted 500,000 to hire entomologists.
“We’re just thrilled to death that our governor and our legislators are looking at this more seriously. I hate that it had to be a Zika (virus) for them to do that, but I am proud that they’re willing to take the steps to protect the citizens of North Carolina.”
Dr. Carl Williams credits local partners, including university researchers like Dr. Richards, with continuing to keep tabs on the mosquito population throughout the state. One of the main objectives of the study is to get an accurate survey of the state’s mosquito population.
“Well, I think it also builds local infrastructure because…to do the work, our university partners are essentially training local health departments and their mosquito control staff on how to do the collections, the speciation, so that this can be done again and monitor it over time, but if we can build that capacity, that really gives us an advantage for whatever the next vector borne disease might be.”
The study is in its early stages, but he said early surveys statewide haven’t shown signs of the aedes aegypti in North Carolina.