Harvey’s Next Danger: Massive Mosquito Clouds

Standing water is breeding billions of post-hurricane mosquitoes, which could transmit diseases like the West Nile Virus

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After the catastrophic devastation of hurricane Harvey, the people of Texas are now facing a slew of problems from contaminated floodwaters to toxic mold to giant alligators sneaking into homes to floating rafts of fire ants. But as Joe Hanson at Texas Monthly reports, Harvey victims have yet another galling problem to add the mix: giant clouds of mosquitoes.

Immediately after the storm, the mosquito population along the Gulf Coast crashed. The insects are usualy pretty robust in this region, but the massive torrents of rain washed away the the mosquitos as well as their larvae, which develop in standing water. Now as the 28,000 square miles of floods are receding, it's leaving behind pools of standing water in its wake. And the mosquitos are returning with a vengeance.

Populations are already rising in some regions. Residents have posted images of people or windows covered in thousands of the insects. Jesse Peña, a resident of Victoria, Texas, volunteering in the recovery of nearby Seadrift, posted an image on Facebook that shows his truck coated in the insects. He included the caption: "In case you thought we were joking."

Peña witnessed vast clouds of mosquitoes while driving through the area. “There were clouds of mosquitoes over trees that looked like spirits,” he tells Elizabeth Abrahamsen at Wide Open Country“I never saw anything like that before. They were still, hovering. Driving through them was literally like driving through the rain.”

While hordes of biting mosquitoes is no joke, public health officials are especially worried about the possible transmission of mosquito-borne diseases like West Nile Virus and Zika. As Julie Beck at The Atlantic reports, risk of transmission is low immediately after the storm because mosquito populations, including most infected insects, were swept away. But that respite might not stick around for long.

In the months after Hurricane Katrina in 2005, mosquito-borne illnesses almost disappeared, Beck writes. But the following year the number of cases of West Nile neuroinvasive disease more than doubled, something public health officials worry could happen in Texas.

“What needs to be done is long-term surveillance beyond this transmission season,” Peter Hotez, dean of the National School of Tropical Medicine at Baylor College of Medicine in Houston tells Hanson. “Given all the West Nile we’ve already seen in Texas in recent years, this means we’re really going to have to keep our eyes on it in the coming months. We can’t really say we’re out of the woods until much later.”

There is still a possibility that Texas could see a bump in disease this year as well. Since the hurricane hit with several weeks of disease transmission season yet to go, it's possible that a re-established mosquito population could begin spreading West Nile. “The timing is kind of interesting,” Hotez tells Beck. “If we were at the end of arbovirus [insect-spread disease] season, or we were headed well into the fall, then the effect would be beneficial because you’re going to wash the mosquitoes away and then basically, transmission season’s over,” he says. “[But] we still have a lot of weeks of mosquito transmission season in Texas left.”

For their part, Harris County tells Hanson that their mosquito abatement equipment survived the flood and they are out aggressively fogging and applying pesticide to standing water. They also urge homeowners to do what they can to drain any standing water on their property.

While disease is in the back of everyone’s mind, it’s the biting that is currently causing problems in some areas, which is slowing down recovery efforts or at least making them even harder. “When they bite it’s like a tiny razor blade that cuts you, and you can’t satisfy the itch,” Peña tells Abrahamsen. “My thoughts were on all the people without power that have to endure them. I had my own blood all over my shirt yesterday from killing them. Repellent only lasts so long.”

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