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Bacteria: The new pirates of the Caribbean?

I missed this yesterday, but here's a fascinating account of reverse zoonosis (essentially the transmission of an infectious disease from humans to non-human animals) on the New York Times Green blog: Apparently the bacteria Serratia marcescens may be responsible for a recent epidemic of the white pox coral disease in the Carribean. Joanna Foster writes:

White pox was first documented off the Florida Keys in 1996, with virulent outbreaks observed in 2003 and 2009. The bacterium infects and kills Elkhorn coral at a rate of up to 10 centimeters, or nearly four inches, a day - far outpacing the coral's regrowth rate of just 10 centimeters a year.

. . .James W. Porter, another lead author on the paper, said in an interview: "These bacteria thrive in the guts of animals. Guts are warm and nutrient rich. Unfortunately, the Caribbean marine ecosystem is getting warmer and having more nutrients dumped into it - in other words, becoming increasingly gutlike."

The referenced paper was published in the journal PLoS ONE. In that paper, the authors note that the epidemic is likely caused by the inadequate treatment of wastewater discharged into the Caribbean. They also raise two other interesting points:

This study brings to light a disease system dynamic, from humans to wildlife, which is the opposite of the traditional wildlife-to-human disease transmission model. The passage of pathogens from wildlife to humans is well documented, but the movement of disease-causing microbes from humans to marine invertebrates has not been shown [42]. This “reverse zoonosis” is all the more interesting because it involves the jump of a pathogen from vertebrate to invertebrate and from terrestrial to marine. Furthermore, disease incidence or severity may increase with rising temperatures [26], [43], [44], reinforcing the importance of near-shore water quality under climate change scenarios.

In other words, they are saying this unusual epidemic may be exacerbated in future by global climate change.

Photo by salin1

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