{"id":41385,"date":"2022-03-29T20:09:41","date_gmt":"2022-03-30T02:09:41","guid":{"rendered":"https:\/\/dh.durangoherald.com\/tj\/climate-change-may-push-colorado-toward-the-goldilocks-zone-for-west-nile-virus\/"},"modified":"2022-03-30T02:09:41","modified_gmt":"2022-03-30T02:09:41","slug":"climate-change-may-push-colorado-toward-the-goldilocks-zone-for-west-nile-virus","status":"publish","type":"post","link":"https:\/\/dh.durangoherald.com\/tj\/climate-change-may-push-colorado-toward-the-goldilocks-zone-for-west-nile-virus\/","title":{"rendered":"Climate change may push Colorado toward the \u2018Goldilocks Zone\u2019 for West Nile virus"},"content":{"rendered":"

\"A
A female Aedes aegypti mosquito, known to be a carrier of the Zika virus, acquires a blood meal on the arm of a researcher Jan. 18, 2016, at the Biomedical Sciences Institute of Sao Paulo University in Sao Paulo, Brazil. (Andre Penner\/Associated Press file)<\/span>du1-i-syn<\/span><\/figcaption><\/figure>\n<\/p>\n

Michael Keasling of Lakewood was an electrician who loved big trucks, fast cars and Harley-Davidsons. He\u2019d struggled with diabetes since he was a teenager, needing a kidney transplant from his sister to stay alive. He was already quite sick in August when he contracted West Nile virus after being bitten by an infected mosquito.<\/p>\n

Keasling spent three months in hospitals and rehab, then died on Nov. 11 at age 57 from complications of West Nile virus and diabetes, according to his mother, Karen Freeman. She said she misses him terribly.<\/p>\n

\u201cI don\u2019t think I can bear this,\u201d Freeman said shortly after he died.<\/p>\n

Spring rain, summer drought and heat created ideal conditions for mosquitoes to spread the West Nile virus through Colorado last year, experts said. West Nile killed 11 people and caused 101 cases of neuroinvasive infections \u2013 those linked to serious illness such as meningitis or encephalitis \u2013 in Colorado in 2021, the highest numbers in 18 years.<\/p>\n

The rise in cases may be a sign of what\u2019s to come: As climate change brings more drought and pushes temperatures toward what is termed the \u201cGoldilocks Zone\u201d for mosquitoes \u2013 not too hot, not too cold \u2013 scientists expect West Nile transmission to increase across the country.<\/p>\n

\u201cWest Nile virus is a really important case study\u201d of the connection between climate and health, said Dr. Gaurab Basu, a primary care physician and health equity fellow at the Center for Climate, Health, and the Global Environment at Harvard\u2019s public health school.<\/p>\n

Although most West Nile infections are mild, the virus is neuroinvasive in about 1 in 150 cases, causing serious illness that can lead to swelling in the brain or spinal cord, paralysis, or death, according to the Centers for Disease Control and Prevention. People older than 50 and transplant patients such as Keasling are at higher risk.<\/p>\n

Over the past decade, the U.S. has seen an average of about 1,300 neuroinvasive West Nile cases each year. Basu saw his first one in Massachusetts several years ago, a 71-year-old patient who had swelling in his brain and severe cognitive impairment.<\/p>\n

\u201cThat really brought home for me the human toll of mosquito-borne illnesses and made me reflect a lot upon the ways in which a warming planet will redistribute infectious diseases,\u201d Basu said.<\/p>\n

A rise in emerging infectious diseases \u201cis one of our greatest challenges\u201d globally, the result of increased human interaction with wildlife and \u201cclimatic changes creating new disease transmission patterns,\u201d said a major United Nations climate report released Feb. 28. Changes in climate have already been identified as drivers of West Nile infections in southeastern Europe, the report noted.<\/p>\n

The relationship between lack of rainfall and West Nile virus is counterintuitive, said Sara Paull, a disease ecologist at the National Ecological Observatory Network in Boulder, who studied connections between climate factors and West Nile in the U.S. as a postdoctoral researcher at the University of California-Santa Cruz.<\/p>\n

\u201cThe thing that was most important across the nation was drought,\u201d she said. As drought intensifies, the percentage of infected mosquitoes goes up, she found in a 2017 study.<\/p>\n

\"Mosquitoes
Mosquitoes pick up the West Nile virus from infected birds before spreading it to humans. (Ricardo Mazalan\/Associated Press file)<\/span>du1-i-syn<\/span><\/figcaption><\/figure>\n<\/p>

Why does drought matter? It has to do with birds, Paull said, because mosquitoes pick up the virus from infected birds before spreading it to humans. When the water supply is limited, birds congregate in greater numbers around water sources, making them easier targets for mosquitoes. Drought also may reduce bird reproduction, increasing the ratio of mosquitoes to birds and making each bird more vulnerable to bites and infection, she said. And research shows that when their stress hormones are elevated, birds are more likely to get infectious viral loads of West Nile.<\/p>\n

A single year\u2019s rise in cases can\u2019t be attributed to climate change, because cases naturally fluctuate by year, in part because of cycles of immunity in humans and birds, Paull said. But we can expect cases to rise with climate change, she found.<\/p>\n

Increased drought could nearly double the number of annual neuroinvasive West Nile cases across the country by the mid-21st century, and triple it in areas of low human immunity, Paull\u2019s research projected, compared with averages from 1999 to 2013.<\/p>\n

Drought has become a major problem in the West. The Southwest endured an \u201cunyielding, unprecedented and costly drought\u201d from January 2020 through August 2021, with the lowest precipitation on record since 1895 and the third-hottest daily average temperatures in that time period, a National Oceanic and Atmospheric Administration report found.<\/p>\n

\u201cExceptionally warm temperatures from human-caused warming\u201d have made the Southwest more arid, and warm temperatures and drought will continue and increase without serious reduction of greenhouse gas emissions, the report said.<\/p>\n

Ecologist Marta Shocket has studied how climate change may affect another important factor: the Goldilocks temperature. That\u2019s the sweet spot at which it\u2019s easiest for mosquitoes to spread a virus. For the three species of Culex mosquitoes that spread West Nile in North America, the Goldilocks temperature is 75 degrees Fahrenheit, Shocket found in her postdoctoral research at Stanford University and UCLA. It\u2019s measured by the average temperature over the course of one day.<\/p>\n

\u201cTemperature has a really big impact on the way that mosquito-transmitted diseases are spread because mosquitoes are cold-blooded,\u201d Shocket said. The outdoor temperature affects their metabolic rate, which \u201cchanges how fast they grow, how long they live, how frequently they bite people to get a meal. And all of those things impact the rate at which the disease is transmitted,\u201d she said.<\/p>\n

\"An
An Aedes aegypti mosquito is photographed through a microscope at the Fiocruz institute in Recife, Brazil. (Felipe Dana\/Associated Press file)<\/span>du1-i-syn<\/span><\/figcaption><\/figure>\n<\/p>

In a 2020 paper, Shocket found that 70% of people in the U.S. live in places where average summer temperatures are below the Goldilocks temperature, based on averages from 2001 to 2016. Climate change is expected to change that.<\/p>\n

\u201cWe would expect West Nile transmission to increase in those areas as temperatures rise,\u201d she said. \u201cOverall, the effect of climate change on temperature should increase West Nile transmission across the U.S. even though it\u2019s decreasing it in some places and increasing it and others.\u201d<\/p>\n

Janet McAllister, a research entomologist with the CDC\u2019s Division of Vector-Borne Diseases in Fort Collins, said climate change-influenced factors such as drought could put people at greater risk for West Nile, but she cautioned against making firm predictions, because many factors are at play, including bird immunity.<\/p>\n

Birds, mosquitoes, humans and the virus itself may adapt over time, she said. For instance, hotter temperatures may drive humans to spend more time indoors with air conditioning and less time outside getting bitten by insects, she said.<\/p>\n

Climate factors like rainfall are complex, McAllister added: While mosquitoes do need water to breed, heavy rain can flush out breeding sites. And because the Culex mosquitoes that spread the virus live close to humans, they can usually get enough water from humans\u2019 sprinklers and birdbaths to breed, even during a dry spring.<\/p>\n

West Nile is preventable, she said. The CDC suggests limiting outdoor activity during dusk and dawn, wearing long sleeves and bug repellent, repairing window screens and draining standing water from places like birdbaths and discarded tires. Some local authorities also spray larvicide and insecticide.<\/p>\n

\u201cPeople have a role to play in protecting themselves from West Nile virus,\u201d McAllister said.<\/p>\n

Kaiser Health News is a national newsroom that produces in-depth journalism about health issues. Together with Policy Analysis and Polling, KHN is one of the three major operating programs at Kaiser Family Foundation. KFF is an endowed nonprofit organization providing information on health issues to the nation.<\/em><\/p>\n","protected":false},"excerpt":{"rendered":"

killed 11 people and caused 101 cases of neuroinvasive infections, the highest numbers in 18 years<\/p>\n","protected":false},"author":1,"featured_media":41386,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[],"tags":[120,289,28,60],"naviga_topic":[],"class_list":["post-41385","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","tag-colorado","tag-disease","tag-headlines","tag-montezuma-county"],"acf":[],"author_name":"dh_admin","_links":{"self":[{"href":"https:\/\/dh.durangoherald.com\/tj\/wp-json\/wp\/v2\/posts\/41385","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/dh.durangoherald.com\/tj\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/dh.durangoherald.com\/tj\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/dh.durangoherald.com\/tj\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/dh.durangoherald.com\/tj\/wp-json\/wp\/v2\/comments?post=41385"}],"version-history":[{"count":0,"href":"https:\/\/dh.durangoherald.com\/tj\/wp-json\/wp\/v2\/posts\/41385\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/dh.durangoherald.com\/tj\/wp-json\/wp\/v2\/media\/41386"}],"wp:attachment":[{"href":"https:\/\/dh.durangoherald.com\/tj\/wp-json\/wp\/v2\/media?parent=41385"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/dh.durangoherald.com\/tj\/wp-json\/wp\/v2\/categories?post=41385"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/dh.durangoherald.com\/tj\/wp-json\/wp\/v2\/tags?post=41385"},{"taxonomy":"naviga_topic","embeddable":true,"href":"https:\/\/dh.durangoherald.com\/tj\/wp-json\/wp\/v2\/naviga_topic?post=41385"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}