New study explores relationship between dust and Valley Fever

New study explores relationship between dust and Valley Fever

New study explores relationship between dust and Valley Fever

AUG 31, 2020

Valley Fever
Atmospheric Science

Above: Aerial view of Twentynine Palms, California. Credit: Dicklyon/Creative Commons

Q & A with Vic Etymezian, Ph.D. 

Vic Etyemezian, Ph.D., is the Interim Vice President of Research at the Desert Research Institute (DRI) and specializes in the study of dust emissions. Vic has been a member of the DRI community since 1999, when he started his career at DRI as a post-doctoral scientist with the Division of Atmospheric Sciences in Las Vegas. He recently published a paper in the International Journal of Environmental Research and Public Health titled “Valley Fever: Environmental Risk Factors and Exposure Pathways Deduced from Field Measurements in California,” working alongside colleagues Antje Lauer, Ph.D. (California State University Bakersfied), George Nikolich, M.S. (DRI), and others, so we connected with Vic to learn more about the project.

DRI: What is Valley Fever?

Etyemezian: Valley Fever is an infection that you can get from breathing in spores of a fungus called Coccidioides. In some people the infection is mild or flu-like, but in others, especially people who are immunocompromised, this fungus can cause a serious or even fatal infection. Valley Fever seems to occur primarily in the southwestern US, but it is also found in parts of Central and South America. The military has a record of people stationed at bases in the southwestern US getting sick from Valley Fever going all the way back to the 1940s, so it does seem to occur in and around the training lands that they use in the southwest. The military also has really good records, so it is likely broadly occurring in the arid southwest –  it’s just that they have great records in these places.

Scientists inspect dust measurement device

DRI’s Vic Etyemezian (left) and Jack Gillies (Right) inspect dust measurement instrumentation mounted onto a telescoping tower at Jean Dry Lake Bed in Southern Nevada. The measurements that ensued were critical for calibrating the TRAKER instrument.

Credit: George Nikolich/DRI.

DRI: How did you originally become interested in studying this disease?

Etyemezian: Six or seven years ago, I was working on a DRI project at NASA’s Armstrong Flight Research Center in the Mojave Desert of southern California related to potential future impacts of climate change on capital infrastructure such as buildings and runways. My colleague, Dr. Antje Lauer from Cal State University Bakersfield, was there at the site working on a different project related to the potential influence of climate change on Valley Fever. Our own Dr. Lynn Fenstermaker (also working on the Armstrong project) and NASA’s now retired Dr. Tom Mace had the foresight to introduce Antje and me to one another and identify that we can leverage each other’s expertise. We got into a discussion of whether there was some overlap between her Valley Fever research and the dust research that George Nikolich and I do. We did a little pilot (exploratory) work together, and then put in a proposal to the DoD SERDP Program to do a project near several military facilities in the Southwest to see if we could say something about how Valley Fever might be changing with climate.

Image of Valley Fever paper

Read the new paper, “Valley Fever: Environmental Risk Factors and Exposure Pathways Deduced from Field Measurements in California”, in the International Journal of Environmental Research and Public Health.

DRI: Tell us a little bit about the paper that you and your colleagues just published. What were your major research questions?

Etyemezian: In this study, we were trying to find out several things, and the paper that was led by my colleague, Dr. Lauer reported our preliminary findings. One, are there any environmental parameters that can help us identify whether or not this Coccidioides fungus will be present at a given site? Can we say that this fungus tends to be found in certain kinds of soils, or on certain slopes of hillsides, or on shaded hillsides, or in soils with a certain chemistry? If so, then we can look at some of these properties and try to identify areas that are fairly high risk for the fungus.

The second goal was to determine whether dust was a possible pathway by which people are getting exposed to this fungus. So, in areas where you find this fungus in the soil, can you also find it in the dust that comes off of the surface during high winds, or in the dust that gets stirred up when someone drives a vehicle along a dirt road? We hypothesized that this study may be of particular relevance for people in the military, because oftentimes they are working in very dusty conditions, especially during training exercises. Our study sites were located around three military bases in southern California, all of which have documented cases of Valley Fever throughout the years.

Researcher conducts a PI-SWERL test near Edwards Air Force Base in California
Researcher preparing the TRAKER instrument for measuring and collecting dust from unpaved roads

Above, left: George Nikolich (Division of Atmospheric Sciences, DRI) notes field conditions as he oversees a PI-SWERL test near Edwards Air Force Base in California. The orange case contains specialized instrumentation for collecting particles that are suspended by the PI-SWERL during its testing cycle. These are later analyzed for fungal DNA. Above, right: George Nikolich preparing the TRAKER instrument for measuring and collecting dust from unpaved roads near Twentynine Palms, California. 

Credit: Vic Etyemezian/DRI.

DRI: What was your/DRI’s role in this investigation?

Etyemezian: Our expertise mainly came in in the area of dust. We used an instrument called the PI-SWERL®, which was developed at DRI, on dozens of test surfaces to simulate high winds on that suspend  dust from the surface into the air. Then we collected that dust and gave it to our colleague, Dr. Lauer, for analysis to see if she could find DNA of the fungus. We also used another device that we developed at DRI called the TRAKER™, which is basically a heavily instrumented vehicle that you can drive on unpaved roads . As you drive on these dirt roads and suspend dust behind the vehicle, you can sample this material, and then subject it to analysis to see if there is genetic material from airborne Coccidiodes spores in that dust.

DRI: What were some of your findings?

Etyemezian: It’s important to emphasize that this was really kind of a pilot study. One of the things that was pretty clear from the study was that there are unfortunately no simple parameters you can look at in the soil to determine whether or not this fungus exists at a given location. It appears to be fairly widespread across the southwest. Another finding was that traveling in a vehicle on unpaved roads in these endemic areas is a plausible pathway for exposure, and farmers or military folks who live and train in these areas might get exposed to potentially high concentrations of infectious fungal material.

Overall, it seems that there are sort of two endpoints in the landscape. If you look at a natural desert landscape that hasn’t been disturbed in some time, you could find a lot of the Valley Fever pathogen in the actual soil, but the potential for the fungus to be suspended under normal windy conditions seems to be quite small. And if you look at an extremely disturbed landscape such as a farm, where you’ve completely changed the original ecosystem, it appears that there’s very little fungus or Valley Fever spores – maybe because people apply fungicide to the crops and are creating not a very hospitable environment. But it seems like there’s a period of time in between, when you’re transitioning from a natural landscape to an extremely anthropogenically impacted landscape, that’s probably when and where the exposure happens.

Researchers standing next to PI-SWERL during a test on a disturbed surface

Student Eduardo Garcia (left, CSU Bakersfield), George Nikolich (middle, DRI), and Dr. Antje Lauer (Right, CSU Bakersfield) standing next to PI-SWERL during a test on a heavily disturbed surface near Twentynine Palms, California.

Credit: Vic Etyemezian/DRI.

DRI: How do you hope that these findings are used?

All of our research findings are preliminary, but they essentially provide a conceptual model of how we think the exposure happens. We think that most of the time when people are exposed to this, it is probably as a result of a recent land disturbance — maybe a construction or farming activity that disturbs otherwise undisturbed landscapes. So, you have this fungus that’s been growing in the soils at some depth below the surface for who knows how long, and then all of the sudden, something changes. You pull off the vegetation, you turn it over, and as a result you bring a lot of this fungus to the surface. Then as a part of that process, you have an enormous amount of material available for resuspension by wind or even direct resuspension. So, I think a logical next step would be to very specifically target those kinds of activities to see if that hypothesis holds true.

Additional Information

The full text of the paper “Valley Fever: Environmental Risk Factors and Exposure Pathways Deduced from Field Measurements in California,” is available from the International Journal of Environmental Health and Public Research:

For more information on Vic Etyemezian and his research, please visit:

For more information on the PI-SWERL (Portable In-Situ Wind Erosion Lab), please visit:

Dust Control at the Oceano Dunes

Dust Control at the Oceano Dunes

Last May, DRI scientist Jack Gillies, Ph.D. spent three weeks at the Oceano Dunes State Vehicular Recreation Area (SVRA), a 3,500-acre area of sandy beach and coastal dune habitat located within the Guadalupe-Nipomo Dunes complex on the central California coast. Unlike most visitors to this popular park, Gillies was not there to camp, or to ride OHVs over the miles and miles of beaches and dunes; he was there to measure the dust.

For more than 100 years, people have visited the Oceano Dunes region to drive on the beaches – beginning in the early 1900s with horse-drawn carriages and early automobiles, then later with ATVs, dune buggies, dirt bikes, trucks, RVs, and other types of vehicles. All of this activity, however, has not been without impact: Dust emitted by the dunes routinely blows toward the nearby Nipomo Mesa area, violating air quality standards for particulate matter and posing a public health threat to residents.

Last year, the Oceano Dunes SVRA was issued an Order of Abatement, which requires the development and implementation of a management plan to bring the park’s dust emissions back into compliance with State and Federal air quality standards within four years. Now, with new funding from the California State Parks Off-Highway Vehicle Division, Gillies and several other DRI researchers – Vic Etyemezian, Ph.D., George Nikolich, and John Mejia, Ph.D.—are continuing a long-term effort to help park officials understand and manage dust emissions from the Oceano Dunes. But in order to stop the dust, it would help to know how it forms, and this is still a bit of a mystery.

Researchers measure dust emissions at Oceano Dunes.

The source of the problem

“Dunes are always sandy, but they aren’t normally dusty; at least not to this extent,” said Gillies, who has worked at the Oceano Dunes since 2010. “Part of our research is to actually come up with the scientific reasons why the dunes are so dusty.”

Neither the park nor the town has long-term air quality data to show what conditions were like prior to the presence of vehicles, says Gillies, but there is evidence that suggests that the presence of the vehicles exacerbates the problem. Gillies and Etyemezian hypothesize that the dust emitted under elevated wind speeds could be a result of the re-working of the dunes by the vehicles and re-shaping of the dunes by coastal winds.

Researchers do know that dust is released from the dunes through a natural process called saltation, in which wind-blown sand particles bounce along the surface of the dune, kicking up smaller particles of dust – and that holding the sand in place helps to prevent that dust from being released.

“When the wind blows the sand across the dune surface, it’s like all these little missiles of sand coming in,” Gillies explained. “That’s what kicks out the dust, and then the dust is dispersed by the wind.”

Tools of the trade

To help park officials identify major sources of dust, Gillies and his DRI colleagues are engaged in an effort to map out specific areas of the park where dust originates. This spring, they collected more than 500 dust emissions measurements in a grid pattern through the OHV recreation area using a tool called the PI-SWERL (Portable In-Situ Wind Erosion Lab).

“The last time we did such an extensive measurement of dust emissions at the Oceano Dunes was in 2013, so it was decided that we should go back this year to update the underlying emission grid and see if, or how much, it has changed,” Gillies said.

PI-SWERL at the Oceano Dunes

Pi-SWERL at the Oceano Dunes. Credit: Jack Gillies/DRI.


The PI-SWERL at Oceano Dunes. A flat blade several cm above the surface in PI-SWERL rotates creating a shear stress like the wind created when it blows across a surface, causes the sand to saltate and the dust is emitted. The inset shows the sand surface after a test. PI-SWERL sits on the metal frame to provide a stable surface for testing. Credit: Jack Gillies/DRI.

The PI-SWERL, which was developed at DRI by Etyemezian and Nikolich, measures the potential for dust emissions from real-world surfaces. It acts as a miniature wind tunnel to simulate the high winds that produce dust storms. The dust emissions measurements are fed into a computer model, developed in part by DRI’s John Mejia, which simulates the action of coastal winds and the subsequent dispersal of dust. Using this model, the team can help park officials identify “hot-spot” areas where dust originates, and target those areas for remediation.

The team has also installed a network of air quality monitors throughout the park, which monitor wind speed, wind direction, relative humidity, and particulate matter. These data are adding to their overall understanding of the spatial variability and strength of the dust emissions at the dunes.

“These data will help us answer questions like whether dust emissions levels are different on weekdays versus weekends, when human activity in the park is higher,” Gillies explained. “It will also allow us to see how things are changing over time.”

Researchers gather dust emissions data at the Oceano Dunes SVRA using the PI-SWERL. May 2019. Credit: Vic Etyemezian/DRI.

Researchers gather dust emissions data at the Oceano Dunes SVRA using the PI-SWERL. May 2019. Credit: Vic Etyemezian/DRI.

Seeking new solutions

As the DRI team works to answer underlying scientific questions about the Park’s dust problem, they are also engaged in efforts to help develop and monitor solutions. They are working with Park officials on various dust control strategies, such as the use of temporary sand fencing, and revegetation with native plants to help hold sand in place and trap moving sand.

“Our aim is to stop the sand from moving, because when you stop the sand moving, you essentially stop the dust from being emitted,” Gillies said.

They are guiding the creation of “vegetation islands” of native plants, similar to that which are found in undisturbed dune areas to the north and south of the SVRA. OHVs are excluded from these areas, as well as from large sections of the park where endangered California least terns and threatened Western snowy plovers breed and nest during spring and summer.

As new dust control measures are added, the team monitors the remediation sites to see if dust emissions levels are reduced. The goal, Gillies says, is to help the park develop a management plan that will bring them into attainment with the Federal air quality standard for particulate matter within four years.

“The park has been ordered to find a solution to this problem, and it’s a problem that has raised a lot of contention among people of the region,” Gillies said. ”There are a lot of people who enjoy OHV recreation at the dunes and their visits contribute to the local economy, and another contingent of people who live downwind of the park and really want to breathe clean air. So, it is an interesting project to work on, both from a scientific perspective and as a project that deals with real-world problems.”

Vegetation islands at Oceano Dunes

At the Oceano Dunes SVRA, native “vegetation islands” are being restored to help reduce dust emissions from the dunes. Credit: Jack Gillies/DRI.

About Jack Gillies: Jack Gillies, Ph.D. is a Research Professor of Geography with DRI’s Division of Atmospheric Sciences. Jack specializes in the physics of sediment transport by wind, and applies this knowledge to solve problems related to air quality. He grew up in Ontario, Canada, and holds bachelors, master’s and doctoral degrees in physical geography from the University of Guelph, Ontario. Jack began his career at DRI as a post-doctoral researcher in 1994, and has been a member of the DRI community for 25 years. To learn more about Gillies and his research, please visit: