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Amid Zika Concerns, Kansas Researchers Target Mosquitoes That Can Carry The Virus

Abigail Wilson
Christopher Rogers, with the Kansas Biological Survey, demonstrates one method of trapping mosquitoes for monitoring.

Updated July 28, 2016: The Kansas Department of Health and Environment has identified three more cases of Zika virus in Kansas, bringing the total number to eight. All of the cases are believed to have been contracted through traveling to countries where Zika is known to be transmitted locally.

Original: The Centers for Disease Control and Prevention recently awarded Kansas more than $350,000 to support efforts to protect Kansans from Zika virus, a mosquito-borne illness. The money will also go toward eliminating adverse health outcomes that can result from Zika infection, including severe birth defects.

Now, state agencies are working to identify and monitor the two species of mosquito that transmit the Zika virus.

Mosquito season went into full swing when early rains and warm temperatures started the population with a bang this spring. But with rising concerns of Zika virus in the United States, the itchy welts that come from mosquito bites are no longer just annoying. They’re scary.

In an effort to lessen fears and keep track of the prevalence of the tiny flying bugs, the Kansas Department of Health and Environment, along with specialists from the University of Kansas, conduct mosquito surveillance each year. Researchers trap and count the insects and identify them by species. The program is funded by a grant from the CDC.

Christopher Rogers, with the Kansas Biological Survey, is one of the researchers tasked with mosquito monitoring in Kansas.

Credit Abigail Wilson / KMUW
A kind of trap used to gather mosquitoes in order to track them for different diseases.

Just off the sidewalk at Chisholm Creek Park in Wichita near the Great Plains Nature Center, Rogers stands beside an interesting contraption. It looks a little like black paint bucket with a long, skinny bird feeder hanging from it. And while seemingly simple, this mosquito trap is a key piece of the puzzle for Kansans hoping to avoid mosquito-borne illnesses.

Of the 50 species of mosquitos in the state, Rogers says only about half bite.

“And of those species that do bite, only the female bites, and she only bites when she needs to lay eggs," he explains.

And in order to find someone or something to bite, the female mosquitoes look for our breath--or, more specifically, the carbon dioxide that we breathe out. Rogers' trap simulates that using a bucket filled with dry ice, which puts off the gas as it melts.

The hanging contraption also has a small light near the top, which serves the same purpose that a lighthouse does for ships at sea. As the mosquitoes fly toward the carbon dioxide, they see the light and think its body heat. That’s how they narrow down their next meal, which, thankfully, this time, is not a person.

“They fly in," Rogers says, pointing at the trap. "And inside of here is a fan, which sucks the mosquitoes down into the sleeve cage."

The sleeve cage is exactly what it sounds like: a sheath of tightly woven netting that traps the inside. Rogers says it can hold anywhere from a few dozen to 7,000 mosquitoes, which he then puts on dry ice to knock them out so he can get to work identifying the insects down to a species level.



Credit Wikipedia.org
The Aedes aegypti mosquito, top, and the Aedes albopictus mosquito.

He says different varieties are distinguishable by the arrangement of veins in their fragile wings or the patterns found in scales, spines and hairs on their tiny bodies. The species he’s looking for are varieties of the Aedes mosquito: Aedes aegypti, which is native to Africa, and Aedes albopictus, which comes from Asia.

“These are the two that we’re most concerned about because they have the potential to carry the Zika virus," Rogers says. "These are the two species that are carrying Zika virus in Central and South America, Puerto Rico, the Caribbean and whatnot.”

If either Aedes variety is found in one of Rogers’ traps, its body is sent to a KDHE laboratory, where it’s ground up.

"We look for the DNA of the virus in the mosquitoes. That way we can tell if the mosquitoes are actually transmitting the disease," he says.

Sedgwick County shared a video of the demonstration:

The state of Kansas has been doing this kind of work – trapping, counting and identifying mosquitoes– for years in order to keep tabs on other mosquito-borne illnesses like West Nile Virus, which first showed up in the state in 2002. Rogers’ work helps state agencies like the KDHE determine where certain species of the insect are found and how dense the population is.

“By knowing what species of mosquitoes are coming into the traps, we can direct Sedgwick County in their efforts to control the mosquito larvae, and they know where to go look for habitat where the larvae may be coming from," he says.

So, that begs the question everyone seems to be asking: Is it just a matter of time before Zika virus does show up in Kansas?

“I’ll ask the right question," Rogers says. "Zika virus has shown up in Kansas in people who went to other places, got the virus, and came here. So, because there are people here who have Zika, and there’s very few, these mosquitoes, all they have to do is go and bite that person and now they’ve got the virus. So far, these people are doing everything in their power not to get bitten by these mosquitoes.”

As of right now, there have been five cases of Zika in Kansas, none of which originated in the U.S. In fact, according to the KDHE, there have been no local transmissions of the virus in the continental U.S. Rogers says the countries that have been inundated with cases of Zika virus tend to be tropical places where mosquitoes are out year-round. One thing in Kansas’ favor is the winter.

“As soon as winter comes, they’re all dead. All that’s left behind is their eggs. Now, as far as we know, so far all the data shows that the mosquitoes are not passing the virus to their eggs," Rogers says.

So that’s a good thing. But, Rogers says, next year, it's going to start all over again.

"If Zika virus does show up in the mosquitoes in Kansas, it’s going to reset every single year," he says. "And it’s probably not going to be as huge a problem as we’re seeing in more tropical areas. We don’t know. We honestly don’t know what we’re up against yet."

Credit Abigail Wilson / KMUW
The net-like traps used by the state can hold thousands of mosquitoes.

That being said, there are efforts that can be made to reduce the chances of getting Zika virus, like using DEET, staying covered, and staying away from places where mosquitoes are likely to be in large numbers, and especially where they breed. Rogers says that doesn’t only mean roadside ditches and stagnant ponds. The species of mosquito that can carry Zika, Aedes aegypti and Aedes albopictus, actually nest in trees with rotten hollows or pockets between limbs that can hold water.

“What they want is water with a lot of rich organic material in there. That’s what you get in a tree hole," Rogers says. "So birdbaths that get filled up with leaf litter, empty jars or tires that get filled up with leaves and sticks, water gets in there and everything starts decomposing. These guys love that.”

Rogers says Aedes aegypti has mainly been found along the Kansas-Missouri border and as far west of that as Topeka. Aedes albopictus has been found in Sedgwick County for quite some time. But according to the KDHE, the precise range of both species is unknown, and just because the mosquitoes are here, that doesn’t mean they’re transmitting Zika to Kansans.

“I’m running traps all across the state to figure out where it lives, why it’s there, how did it get there," Rogers says.

And with that data, the KDHE should be able to assess potential threat levels should Zika virus every show up in mosquitoes in Kansas.


Follow Abigail Wilson on Twitter @AbigailKMUW.

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