August 21, 2024
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West Nile virus spreads in areas where climate change brings warmer, wetter weather
Houston’s warm, wet spring, thanks in part to climate change, was ideal for mosquitoes and the West Nile virus.
Floodwaters submerge cars and reveal the tops of mailboxes on Friday, May 3, 2024, in a residential neighborhood in Woodloch, 30 miles north of Houston.
Kirk Sides/Houston Chronicle via Getty Images
Climate Wire Houston is seeing a surge in West Nile virus cases, which they blame on climate change.
As of mid-August, 24 people in Harris County, Texas, had been infected with the virus and more than 600 mosquito samples had tested positive for the virus. In contrast, over the past five years, the area had seen fewer than 10 cases per year and no more than 320 mosquito samples tested positive.
This is just the latest example of climate-driven weather increasing the transmission of vector-borne diseases.
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“The virus loves heat,” said Maximere Vigilant, mosquito and vector control officer for Harris County Public Health.
Vigilant said climate change has contributed to Houston’s rise in cases in several ways.
First, the city experienced above-normal rainfall in the spring, which led to wet, warm weather that led to an increase in the local mosquito population, and then unusually hot weather in the spring and summer allowed the virus to multiply and spread among migratory birds, which then infected mosquitoes that bit them.
“The virus multiplies in the bird host and is then transmitted to the mosquito when it feeds on the bird’s blood,” he said.
West Nile virus is the leading cause of mosquito-borne illness in the United States. Most people infected with the virus don’t feel sick, but one in five develop symptoms, including fever, according to the Centers for Disease Control and Prevention. Approximately one in 150 infected people develop severe or fatal illness, and infection can lead to lifelong autoimmune disorders.
The impact of climate change on West Nile virus cases at a national level can be difficult to track, in part because different weather conditions influenced by climate change can, in turn, affect mosquito and bird populations and thus the transmission of the virus.
The EPA noted that case numbers vary widely across the country, with the highest incidence occurring in 2012.
Generally, humid and warm weather increases mosquito reproduction, but drought has also been associated with increased virus outbreaks. Human exposure to mosquitoes and the diseases they carry also varies depending on the geography of a region.
But West Nile virus is a growing concern in some areas, said Sarah Hunt, president of the Rainey Center for Public Policy, which helps connect local government officials with experts through its Leadership Alliance for a More Perfect Commonwealth program.
“We may disagree about the extent to which climate change is having an impact, but regardless of political stance, we all see the impacts of diseases and vectors that come from rising temperatures and water being in places where it shouldn’t be,” she said.
That was the case two years ago, when Utah County, Utah, recorded its highest snowfall in 175 years. Local officials knew there could be problems if melting snow sent water into normally dry areas, activating mosquito eggs that had been dormant for years.
“We knew it would be nine or 10 years before those eggs hatched, so we needed to take steps ahead of time to prevent a record outbreak like West Nile or Zika,” County Commissioner Amelia Powers Gardner said.
The county used about $250,000 in emergency flood funds to purchase two drones to spray insecticide in hard-to-reach areas and prevent mosquitoes from hatching.
For Powers Gardner, the issue is personal: She contracted West Nile virus as a college student and still suffers from photosensitivity, muscle loss and other symptoms of a related autoimmune disease.
“This wasn’t just a matter of annoying mosquitoes. This was a public health crisis that we needed to avoid,” she said.
Source E&E News Posted with permission from POLITICO, LLC. Copyright 2024. E&E News delivers news that matters to energy and environmental professionals.
