A study published in GeoHealth on July 171 challenges 2021 research that suggests there is no consistent link between dust storms and Valley Fever. The authors of the new paper say the data set used in the 2021 analysis – the Storm Events database, maintained by the US National Oceanic and Atmospheric Administration (NOAA) – is notorious for containing errors, missing certain information and using the definition of “dust”. storm’, which conflicts with that used by most weather organizations. As a result, they say the jury is still out on the dust storm-Valley Fever connection.What qualifies as a dust storm? That’s one of the questions at the center of the debate over the phenomenon’s role in the spread of Valley Fever, an infectious disease caused by inhalation of the soil-dwelling Coccidioides fungus in the western United States.
“Based on what we know about the fungus, it’s dust-borne, and there’s no reason to believe that dust storms can’t carry it,” says co-author Morgan Gorris, an Earth systems scientist at Los Alamos National Laboratory. in New Mexico. Andrew Comrie, a climate and health scientist at the University of Arizona in Tucson who wrote the 2021 paper, acknowledges that the database could be more complete, but still thinks it’s a robust enough representation of the large dust storms his analysis would pick. to subsequent jumps in cases of Valley Fever. “If there is a reliable signal, it should show up,” he says.Finding out whether — and how — dust storms increase the risk of disease is important, the researchers say, as cases increase and would help prioritize effective disease mitigation strategies.
Fungal fever
Of the roughly 20,000 valley fever cases reported to the US Centers for Disease Control and Prevention in 2019, the vast majority occurred in California and Arizona. Symptoms of the disease, which include fatigue, fever and cough, can last for several weeks to months. In severe cases, the infection can lead to scarring of the lungs or death.Gorris and his colleagues analyzed nearly all 76 dust events in Comrie’s paper and found that 47% did not constitute a dust storm as defined by the World Meteorological Organization (WMO), the UN’s atmospheric science body. The WMO defines a dust storm as an event in which the dust in the air is so dense that visibility is reduced to one kilometer or less. The team found an additional 30 events in the Phoenix area that meet the definition and are missing from the NOAA database.
The NOAA Storm Events Database currently defines a dust storm as an event in which visibility is reduced to about 0.4 kilometers, a limit that some researchers say is too narrow. Although the vast majority of reports come from trained storm spotters, other sources include automatic weather stations, law enforcement, and the public. “We are working on ways to potentially improve the database and data reporting in the future,” says Gordon Strassberg, program manager for storm data at the National Weather Service, operated by NOAA. “With more storm events and as the database continues to grow, it can be challenging,” he says, “but we will continue to provide the best data we can.”
Although NOAA’s database contains the best available information on dust storms, the authors of the new study believe it is unsuitable for assessing the phenomenon’s relationship to Coccidioides, in part because of inconsistent categorization of dust events. “Posts are very subjective; the same dust event could be categorized as a dust storm, dust blowing, or simply a haze,” says study co-author Karin Ardon-Dryer, a dust researcher at Texas Tech University in Lubbock.”The devil is in the details,” says co-author Daniel Tong, an atmospheric scientist at George Mason University in Fairfax, Virginia. “We need to be careful when using this data – and be careful about the conclusions we draw from it,” he adds.
Soil study
Comrie says his work is solid. Both he and the authors of the new research agree that a better understanding of the environmental conditions that favor the fungus that causes Valley Fever is key. “We need to get to the bottom of how Coccidioides works,” he says.He adds that further efforts are needed to determine which soils carry the greatest risk of transmission of Valley Fever. A 2020 study found that soil where burrowing animals live has a high probability of this fungus3. Comrie suggests that small burrowing mammals prefer desert habitats that typically have vegetative cover or biocrust, making the surface less likely to emit dust, while large dust storms often start in disturbed areas such as abandoned agricultural land, during strong wind events.
The authors of the new paper identified several measures needed to better understand the relationship between dust storms and Valley Fever risk, including a consistent definition of a dust storm, a quality-controlled database for dust storms, and mechanistic models of Coccidioides transport. Comrie adds another: measuring viable Coccidioides spores to determine which dust events carry the greatest risk. To date, only one study has taken this approach, finding more disputes on non-dust storm days than on dust storm days4.
Progress is slow, Comrie says, because Valley Fever is a regional disease and those studying it don’t get much funding. “We’re just getting to the edge of understanding. Although scientists are eager to understand how, when and where the transmission and risk of Valley Fever is greatest, doctors say there are plenty of other health reasons to avoid the dust, including its link to chronic lung and heart disease. “The bottom line is, you don’t want to breathe those tiny particles anyway,” says George Thompson, co-director of the Valley Fever Center at the University of California, Davis.
Source Journal Reference: Virginia Gewin, Dust-up over dust storm link to ‘Valley Fever’ disease, Nature News (2022), https://www.nature.com/articles/d41586-022-02089-w
