New Orleans Amps Up Mosquito Research To Combat Zika

May 23, 2016

The recent outbreak of the Zika virus has New Orleans on edge. The Gulf Coast is considered the most vulnerable part of the U.S. Mayor Mitch Landrieu has asked Congress for money to fight Zika, as the city continues local efforts to understand the mosquito-borne disease.

Entomologist Sarah Michaels works for the Mosquito, Termite and Rodent Control Board. It’s been around 100 years. Her job is to catch mosquitoes so they can be tested for diseases. To nab them - she goes for their weakness - the nasty smell of body odor and human sweat. She uses a small tub of water that has been infused with hay and fish oil emulsion and aged for about a week. “It smells awful but they really like it,” says Michaels.  

The mosquitoes fly towards the stinky water, which is in the bottom of a tray, and a small fan sucks them up through a PVC pipe and into a net, where they can’t escape.

To most of us they all look the same, but there are many different types of mosquitoes, about sixty in Louisiana. The two Michaels is looking for are called “Aedes aegypti” - which definitely spreads Zika, and “Culex,” which might.

She leaves the traps out overnight, when the bugs are most active, and comes back the next the morning to see what she’s got. She carefully detaches the net from the PVC pipe and pulls the drawstrings closed. Hundreds of mosquitoes buzz around in the trap. She dumps the stinky water out, takes the fan and battery pack off and places the pieces, along with the buzzing bags of mosquitoes, into the back of her car before heading off to the next site. These efforts fit into the city's new 50-page Zika control plan, which was released in April and details how city agencies will work together to combat and monitor for the disease.

Michaels collaborates with the Tulane University School of Public Health and Tropical Medicine, where professor Dawn Wesson and her students are hatching and raising a few different species of mosquitoes. They raise Aedes aegypti larvae in a lab downtown, and study them to learn about their behavior and how they move around the city.

Associate Professor at Tulane University's School of Public Health and Tropical Medicine, Dawn Wesson, studies mosquitoes at her downtown lab.
Credit Tegan Wendland / WWNO

Wesson says, “Unfortunately, the species that is a better vector for Zika has been expanding its distribution in New Orleans over the last ten years or so, since Hurricane Katrina.”

She says the trees that were lost and the drought that followed created perfect breeding grounds. So far no one has contracted the disease in Louisiana. There have been four travel-related cases, but none were transmitted locally.

While the climate is right for these Zika-carrying mosquitoes, the conditions have to be right for the disease to spread. For that to happen one would have to bite someone who has the virus already, likely someone who just came back from traveling in South America or another high-risk place. Wesson says that then the insect would have to live for two weeks in order to incubate the disease and then bite someone else.

“When it takes that next blood meal, it has to salivate, which allows the blood to not clot and that’s when the virus has grown inside it’s body and transmit it to a new person,” says Wesson.

She says the city has studied mosquitoes for long time. After all, in the 1850’s nearly 8,000 people died from mosquito-borne yellow fever. Without understanding transmission, people burned tar and shot off cannons in desperate attempts to scare off the disease. Today, most of us have screened in houses and access to repellent.

City Health Director, Charlotte Parent, says citizens have to do their part. “Help us create an environment that does not allow these mosquitos to breed and grow,” says Parent. “We know we have a problem, we live on a swamp, but because we do everyone needs to be aware and do what they can to decrease those chances.” Such as dumping out standing water and wearing lots of repellent.

The city is prepared to respond, if scientists find infected mosquitoes, with a targeted sweep of the affected neighborhood. But Michaels says different areas have different risks, “In areas where the houses are a little farther apart - we have a little lower human population density, we have a little lower mosquito density,” she says that’s a lower-risk area.

A drawing in a mosquito lab at Tulane University shows three different types of the insect that can spread Zika virus.
Credit Tegan Wendland / WWNO

But when people live close together and don’t have access to central air conditioning, leave their doors and windows open and spend a lot of time outside – that creates a high risk of transmission. This time of year, New Orleans has a lot of neighborhoods with those risk factors.

Support for WWNO’s Coastal Desk comes from the Walton Family Foundation Coypu Foundation and Greater New Orleans Foundation. This story was produced in collaboration with The Lens.