Valley fever (cocci dioides), a fungal disease in the Arizona, New Mexico and California, has received a great deal of media attention lately, with good reason. There have been over 20,000 cases documented, which likely is only a fraction of the total number of people infected. Tom Geoghagen of the BBC has a good piece on the disease, and the video interviews of the affected families are heartbreaking. In late June 2013 a judge in California ordered California to move inmates held in two prisons in San Joaquin in order to reduce their risk of contracting the disease, which made people living in local communities wonder if they should also move. This particular fungal infection is indigenous to the Americas (the first person on record to die of it was an Argentine soldier) but other fungal infections are emerging because of biological globalization. The expansion of the chytrid fungus is wiping out amphibians around the planet. In the early twentieth century a fungal blight from Asia wiped out perhaps four billion chesnut trees in the United States. Two teams of researchers have recently created strains of the chesnut tree that may resist infection, which provides a sense of hope for this species’ future. Still, humans are also vulnerable to an introduced infection, such as a new fungal disease that first emerged on Vancouver Island, and is now spreading in the Pacific Northwest.
Cryptococcus gatti is a fungus typically found amongst eucalyptus forests in Australia and Papua New Guinea. How it arrived on Vancouver Island is unknown, although it is assumed that it was carried on a lumber shipment. Since the first human case in British Columbia in 1999, it has since spread to Washington State and Oregon. In humans, the fungus typically causes pneumonia, although it can spread in the nervous system and other tissue. One of the first cases on Vancouver Island was a woman who had gone kayaking in a provincial park, where she likely acquired the infection. The fungus ultimately spread to her brain and she died in 2002. The disease has a fatality rate to date of 25% of people who are diagnosed, although many people who are infected may not become symptomatic. Some idea of how widespread the spores are can be gained from the fact that in the summer of 2012 a harbor porpoise stranded on the coast of Vancouver island, which was found to have an extensive fungal infection upon autopsy. It was not the first such case. Other animals are also impacted by this disease, including cats and dogs.
Some scientists have wondered if the dispersal of the disease has been a result of warmer summers, given that this is typically a tropical disease. If so, the emergence of this pathogen may be associated with global warming. In any case, this fungus is certainly the part of a larger exchange of species between the Old World and the New that has been called the Columbian Exchange. For anyone curious about this exchange, there is no better introduction to this topic than Alfred Cosby’s book. When most people think of globalization they think about economics, and then perhaps secondarily political and cultural globalization. It’s equally important to remember that globalization is also a biological process, and one that can affect our health in unexpected ways.
Shawn Smallman, Portland State University