Valley Fever is a fungal infection caused by coccidioides, organisms that reside in the soil here in the Southwest. It's one of the reasons I stay away from construction sites and swirling dust now that we live in Arizona. According to Wikipedia, "Coccidioides immitis is dormant during long dry spells, then develops as a mold with long filaments that break off into airborne spores when the rains come. The spores, known as arthroconidia, are swept into the air by disruption of the soil, such as during construction, farming, or an earthquake."
Residents of Joplin, Missouri were exposed to a similar fungal organism, and the resulting systemic infection proved fatal to at least three of the tornado victims. Dr. Uwe Schmidt, an infectious disease specialist at Freeman Health System, said his hospital treated five Joplin tornado victims for the infection, known as zygomycosis (zy'-goh-my-KOH'-sihs). According to this June 10 Associated Press article:
Zygomycosis, also known as mucormycosis, is a sometimes-fatal infection that spreads rapidly and can be caused by soil or vegetative material getting under the skin. It's more prevalent in people with weakened immune systems or untreated diabetes but can affect healthy people who get badly hurt.
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The Springfield News-Leader reported that the department sent a memo Monday to area health providers warning them to be on the lookout for the infections.
In the aftermath of the tornado, Freeman Health System treated more than 1,700 patients. Doctors from St. John's Hospital, which was badly damaged by the twister, treated patients at makeshift facilities.
"These were very extensive wounds," Schmidt said. "They were treated in the emergency room as quickly as possible."
A week after the tornado, patients began arriving with fungal infections.
"We could visibly see mold in the wounds," Schmidt said. "It rapidly spread. The tissue dies off and becomes black. It doesn't have any circulation. It has to be removed."
Schmidt said the infection is sometimes seen in survivors of mass trauma such as the 2004 tsunami in Indonesia.
"This fungus invades the underlying tissue and actually invades the underlying blood vessels and cuts off the circulation to the skin," he said. "It's very invasive."