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Are more dust storms in the southwestern US causing a spike in valley fever cases?

Researchers have discovered a possible link between the rise in both dust storms and valley fever cases in the southwestern United States over the previous two decades.

A study from the National Oceanic and Atmospheric Administration (NOAA) shows that dust storms have dramatically risen by 240 percent from the 1990s to the 2000s.

In the Southwest, the average number of windblown dust storms increased from 20 per year in the 1990s to 48 per year in the 2000s, according to the NOAA-led study.

Dust storms, also known as haboobs, usually last up to half of an hour and happen when the front of a thunderstorm cell pushes air downward and forward.

Dust storm in Arizona

A dust storm creates a glowing red sky over Arizona during sunset. (Photo/BCFC/Getty Images)

They typically occur during monsoon season in the Southwest and are common in states including Arizona, New Mexico, California and Texas.

Winds of up to 60 mph can swirl up dust and sand to heights of 10,000 feet, according to NOAA.

NOAA researchers found that the drying trend responsible for the dust storm increase was the result of small changes of sea surface temperatures in the northern Pacific Ocean.

The study showed that sea surface temperatures were warmer in the North Pacific during the 2000s than they were during the 1990s.

Those changes, paired with California’s colder coastal waters, allowed for “cooler and drier northerly winds from the North Pacific into the southwestern U.S., helping to dry the soil,” according to NOAA.

The study also mentioned the potential of another Dust Bowl occurring in the near future.

“The Dust Bowl that happened in the 1930s is really an unfortunate convergence of three things: an extremely severe drought; a great depression and economic downturn that led a lot of people to abandon their farms; and unwise land care practices,” said University of Texas at El Paso professor Dr. Thomas Gill, who contributed to the study.

“Hopefully we won’t have that combination of events happening again,” Gill said. “But we know from the paleoclimate records that megadroughts can happen.”

Megadroughts are prolonged periods of abnormally low rainfall lasting two decades or longer, according to NASA.

Dust storms and valley fever: A possible link?

Dust storms not only cause hazardous driving conditions, but may also contribute to the rise in valley fever cases in the Southwest, according to research.

Coccidioidomycosis, more commonly known as valley fever, is caused by a soil-dwelling fungus found the Southwest and parts of Mexico, according the Centers for Disease Control and Prevention (CDC).

NOAA study - spike in dust storms and valley fever

NOAA data shows the nation’s largest number of dust storms from 1988 to 2011 are concentrated in the Southwest states – the same states reporting the nation's highest numbers of valley fever cases. (Image/NOAA)

Dust particles from soil carry microscopic fungal spores in the wind when soil is disturbed, according to the Valley Fever Center for Excellence (VFCE) at the University of Arizona.

It only takes one breath of a single spore to become sickened by the incurable lung infection, but most people who inhale the spores do not experience symptoms, the CDC reports.

The VFCE states that valley fever peak seasons occur from June to August and October to November in Arizona; California’s peak season is also from June to August.

According to the Arizona Department of Health, factors including “changes in precipitation, dust storms and other weather-related phenomena that may affect fungal growth, spore formation and dispersal” can all contribute to valley fever cases.

From 2000 to 2011, the Southwestern infection rate mysteriously rose more than 800 percent, NOAA researchers found.

Valley fever facts

The study showed that in some parts of the Southwest where valley fever is common, dust storms were found to be better correlated with the illness than any other known controlling factor.

However, NOAA researchers concluded that further studies are needed to confirm the links.

“It may also be that the dust storms are indicators of a climate which allows spores to grow more readily or get in the air more readily,” said VFCE Director Dr. John Galgiani.

“There are a lot of people who have never been in a dust storm who get valley fever, so I think it would be pretty hard to conclusively show that,” said Dr. Janis Blair, a Mayo Clinic infectious disease specialist.

“It seems like a plausible explanation for the rise, but we’ve also got rising population, more immunosuppression and more development of the desert land than we’ve ever had,” Blair said.