A record-breaking surge in the mosquito population in and around Las Vegas has raised concerns about the spread of West Nile virus, with local health officials urging the public to take precautions to avoid getting bit.
The Southern Nevada Health District has identified a concerning number of mosquitoes carrying the virus, with 169 of over 24,000 pools of mosquitoes testing positive for West Nile virus across 25 southern Nevada ZIP codes.
West Nile virus can cause fever, headaches, vomiting, and diarrhea, and is fatal in about 1 of 150 cases. There are no vaccines or medications to treat or prevent the mosquito-borne illness.
The district has also identified six pools in the Las Vegas area that tested positive for St. Louis encephalitis virus, a mosquito-borne disease that can cause fatal inflammation of the brain.
The situation in Las Vegas offers a case study on how climate change could affect human health, as rising temperatures and drought conditions in the state create ideal conditions for mosquitoes to breed.
Climate change increases average global temperatures and precipitation levels, fostering conditions that are ideal for mosquitoes, which breed in still, warm water. It also extends the length of warm periods, prolonging the active season for mosquitoes.
The first case of West Nile virus in Las Vegas was recorded in 2004, five years after the United States' first case was documented in New York City in 1999.
Las Vegas' most recent West Nile outbreak occurred five years ago, resulting in 43 human cases. District health officials are concerned that this summer could be far worse.
The vast majority of the surge in mosquito populations in Las Vegas have been Culex mosquitoes, a primary vector for West Nile virus.
However, another mosquito species that does not carry the virus, Aedes aegypti, has also become more common in Las Vegas, attributed to the impacts of climate change.
Louise Ivers, a professor of global health and social medicine at Harvard Medical School, said situations like the one in Las Vegas will become more common as climate change continues to boost infectious disease globally.
Public health officials are urging the public to take precautions such as emptying open containers filled with water outside, maintaining swimming pools, wearing protective clothing, and using bug spray to avoid getting bit.
