Valley fever is endemic to hot and dry areas like the southwestern United States and California's San Joaquin Valley, but scientists at the University of California, Irvine predict that climate change will cause the proportion of fungal infection to double this century, reaching this area. previously untouched areas throughout the western United States
In a recent study published in the journal American Geophysical Union GeoHealth, interdisciplinary UCI researchers claim that in the high-heat scenario, the list of affected states will jump from 12 to 17 and the number of individual cases of heat in the valley will increase by 50 percent by 2100. States predicted to host newly endemic counties are Montana, Nebraska. North Dakota, South Dakota and Wyoming, and the disease is expected to become more widespread in Colorado, Idaho and Oklahoma.
The range of valley fever will increase significantly. We made projections by the end of the 21st century, and our model predicts that valley fever will travel further north across the western United States, especially in the rain shadow of the Rocky Mountains and the Great Plains, and by then, many western United States will be considered endemic. "
Morgan Gorris, lead author and former UCI Ph.D. student of Earth System Science
Gorris received his PhD in August.
The current endemicity map of Valleys fever used by the National Centers for Disease Control and Prevention is based on a skin test conducted at the San Diego Naval Base in the 1940s. Using these decades-old data as a starting point, Gorris collected data from the health department about valley fever cases reported by hospitals in many western states.
She and her team then studied the climatic conditions in the areas where Valley fever is most common. They concluded that all counties with more than 10 cases per 100,000 population had average annual temperatures above 10 degrees Celsius (50 degrees Fahrenheit) and precipitation below 600 millimeters (23.6 inches).
"Morgan made this model based on temperature and precipitation; it provides similar but not exactly the same projections of where the CDC says Valley Valley," said co-author James Randerson, chancellor and Ralph J. and chairman Carol M. Cicerone u Earth System Science. "In fact, we think it could direct efforts to build a better modern map of where the disease threatens public health."
Gorris said the study really focused on predicting the spread of Welsh fever: "Both temperature and precipitation are expected to change significantly in the western United States in the coming decades, but increasing temperatures in already dry conditions will allow the disease to spread."
Currently, parts of California and the southwest are particularly suited to the cultivation of the fungus, scientifically known as Coccidioides. Overcast winter rain on dry soil allows the fungus to grow below the surface. When the soil dries, the elongated parts of the fungus separate into spores, some 2 microns in diameter. If disturbed by earthworks or worker boots, particles can be lifted into the air and inhaled by people in the area.
Workers in construction and agriculture, as well as prisoners who pave roads and deal with fires in remote locations, are especially sensitive to breathing spores from the air. This is a growing public health concern as the number of cases in California and other regions increases with time.
Once in the lungs, the fungus transforms from a spherical shape into spherules, tiny balls that grow and spread in lung tissues. About 40 percent of those who breathe spores become ill. The early symptoms of valley fever are similar to those of the flu: cough, fever, chills and night sweats. For this reason, the disease is often misdiagnosed and can be treated. In advanced cases, the fungus can spread from the lungs to other parts of the body, potentially causing skin lesions that can result in loss of limbs.
In extreme cases, the disease can travel to the brain, leading to swelling and death. About 5 percent of people who suffer from fever in the Valley will be severe and 1 percent will die. Pregnant women, the elderly, and individuals with HIV are considered more vulnerable to severe forms of valley fever. Filipinos and those of African descent are also at increased risk. The disease disproportionately affects people from low-income communities, Randerson said.
"By 2100, for a common scenario where we do not take serious measures to limit climate change, we would anticipate a doubling of the area in which this disease is present," he said. "It's a big spread and especially worrying because the Valley Fever will affect intact communities throughout the West."
University of California – Irvine