Virus Spread Correlates With Climate Change in U.S. According to Healthline Study

Study takes a fresh look at the relationship between infectious diseases and climate change, with a focus on the West Nile virus in the U.S.

SAN FRANCISCO—August 20, 2020—Rising temperatures brought on by climate change have contributed to a prevalence of cases of West Nile virus in the United States, according to a study released today.  The study, West Nile virus in the U.S.: A case study on climate change and health, is published in Medical News Today, sister site of, the flagship digital health brand of Healthline Media. The study features two interactive maps with new data points from the Centers for Disease Control and Prevention (CDC) that show temperature fluctuations in the U.S. and the concurrent spread of West Nile virus from the years 1900 to 2020. 

“The world is focused on the COVID-19 pandemic right now, but other diseases are still out there and on the attack,” said Medical News Today Editor in Chief Robin Hough. “Understanding how West Nile virus spreads and its relationship to climate change helps us educate our audience about disease prevention, including West Nile and similar viruses. 

“Humans can control the impact on the environments we inhabit,” Hough added. “That is, perhaps, the most crucial step in ensuring we do not accelerate the arrival of another future health crisis.”

Highlights From the Study

  • The spread of West Nile virus-carrying vectors in the U.S. is likely explained by temperature extremes and, in some areas, the increased frequency of droughts.

  • While the number and density of West Nile virus cases have ebbed and flowed across the U.S., from 2004 and until 2019 the virus has been a constant in the Southwest and particularly in California.

    • Temperatures in the Southwest have been consistently high, on average, compared with other U.S. regions, and the levels of precipitation have remained low, leading to a more arid climate.

World Mosquito Day

This case study is intended to contribute to global conversations taking place on World Mosquito Day. It commemorates the discovery that mosquitoes carry and transmit malaria to humans and also seeks to highlight the importance of mosquito control. Over one million people worldwide die from mosquito-borne diseases every year, according to the American Mosquito Control Association.

Climate Change and Its Impact on the Future of West Nile Virus in the U.S.

Data from the CDC indicate that in 2019 there were 958 cases of West Nile virus infections in humans across the U.S. Of the total number of cases, 626 affected the brain and central nervous system. 

Changes in weather, including increased rainfall, extreme weather events such as flooding, and more violent heatwaves, have impacted patterns of insect activity, as well as created environments that are more suitable for the transmission of viruses. 

Medical News Today is the fourth largest digital health brand in the U.S. Healthline is the nation’s #1 brand in the category.

About Healthline Media
San Francisco-based Healthline Media’s mission is to empower people to be their strongest and healthiest selves by being a trusted ally in their pursuit of health and well-being. The company’s properties include and Healthline Media’s sites provide evidence-based articles with the highest standards of medical integrity that support the modern health consumer with a whole-person approach to health and wellness. Healthline Media is the top ranked health publisher and number 39 on Comscore’s Top 100 Property rankings through January 2020. Across all of its properties, Healthline Media publishes articles authored by more than 120 writers and reviewed by more than 100 doctors, clinicians, dietitians, and other experts. The company’s repository contains more than 70,000 articles, each updated with current protocol. More than 250 million people worldwide and 87 million people in the U.S. visit Healthline’s sites each month, according to data from Google Analytics and Comscore, respectively. Healthline Media is owned by Red Ventures.

About Healthline Media

As the #1 health media property in the US, Healthline Media reaches more than 94MM unique visitors each month (Comscore, August 2021). We provide credible health information with a compassionate approach.