Wednesday, November 26, 2014

A Fungus Among Us

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A rare, fungus-spawned disease that mimics cancer thrives in Arizona. Just another weird local bug.
It’s a medical mystery worthy of a House season cliffhanger: A treatable infection that strikes few and far between, with a mere 44 known cases worldwide between 1964 and 2008. Just 19 occurred in the U.S., according to a recent survey by the Mayo Clinic in Scottsdale – but 17 of them were in Arizona.
Scientists dub the infection GIB (gastrointestinal basidiobolomycosis). It’s not pretty: a mass in the GI tract often mistaken for cancer or other ills. It seems to be the immune system’s reaction to a soil-dwelling fungus, B. ranarum – the latest odd pathogen in a state that seems to have more than its fair share, including the notorious valley fever.
“The disease [GIB] remains extremely rare,” says Dr. H. R. Vikram, the Mayo infectious disease specialist who led the survey. He’s seen only two cases, including the last known in Arizona, in 2008. The malady is not contagious, and not fatal if treated with drugs or surgery. The only known GIB-related death in the U.S. happened in Florida, in 1986; the world death toll is eight.
That was enough to alert doctors to GIB’s cancer-mimicking ways, sending Vikram and colleagues to scour medical literature and track down doctors who saw infected patients, to compile their definitive survey.
Still, the fungus presents more unknowns than the George Zimmerman shooting trial. How it infects people is one question. Consuming dirt or contaminated food are the most likely culprits. The fungus can be found in soil or reptiles and other animals, and many patients were avid gardeners. One had pica, a compulsion to eat dirt and other non-food substances.
What the fungus is doing in Arizona is another question. It originates in the tropics, where it causes skin lesions, not intestinal problems. “There’s something about Arizona, especially in Pima and Maricopa County, that seems to be ideal for this particular fungus to grow,” says Dr. Rebecca Sunenshine of the Maricopa County health department. Arizona’s rare ecology of dry soil hit by seasonal monsoon-like storms may constitute an ideal culture for the fungus.
Health officials watch other diseases that appear to have an affinity for Arizona. The tick that carries Rocky Mountain spotted fever flourishes in the northern and eastern parts of Arizona; in 2010, the state accounted for 17 of the roughly 200 hundred cases nationally. Our crossroads location also puts officials on alert for whooping cough – Maricopa County alone saw 700 cases last year; officials consider it the worst outbreak in 55 years – and tuberculosis from south of the border, says Dr. Cara Christ, chief medical officer for public health at the Arizona Department of Health Services. With 69 cases and four deaths in 2011, Arizona is also vulnerable to the mosquito-borne West Nile virus; infection rates here are about five times the national average.
Of course, the best-known Arizona disease is valley fever, caused by inhaling a soil-dwelling fungus called coccidiodomycosis not related to GIB. Sixty percent of U.S. valley fever cases occur in Arizona; ADHS recorded 16,000 in 2011. Christ gets calls from out-of-state doctors looking for advice on treating the unfamiliar disease, which sits dormant in dry, parched soil and turns into a mold when rains come, ejaculating light-as-air spores that are unwittingly inhaled by its victims. The University of Arizona is researching a valley fever vaccine, but that med is years away, according to experts.
Which leaves the new kid on the block: GIB. Vikram expects to collect more data, including whether the number of cases is growing or holding steady. As of mid-spring, there had been no 2012 cases. Asked if the fungus could mutate and become more infectious, à la valley fever, he replies: “No one knows at this point.”
Bottom line: “I don’t think [people] should be very worried,” Christ says. “It’s one of those rare, rare diseases. If you’re out digging in the dirt, just make sure that you’re washing your hands adequately afterwards.”

 

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