The Ecological Impact of Sylvatic Plague

Charlie Kammerer

The Sylvatic Plague is a devastating bacterial infection that affects a wide range of mammals. The disease can affect humans, but it most notable infects prairie dogs with mortality rates upwards of 90%.   The disease is spread most easily in the summer months when the temperature is higher due to its transmission through a flea vector. Flea populations have trouble surviving in sub-zero temperatures.

Yersinia pestis, the bacterium responsible for this disease in prairie dogs, is also responsible for the plague in humans. Although historically lethal, antibiotics are now available to treat the disease easily so transmission to humans is not a major concern. What is an issue is the effect that a reduction in prairie dog population has on black footed ferrets. These ferrets are already endangered and their primary food source is prairie dog. Combine a significant decrease in their main source of nutrition and add that they can also be infected with the disease and you get a perfect storm scenario that could lead to the extinction of the black footed ferret.

One way to prevent the spread of Sylvatic Plague is to treat the fleas that carry the disease with pesticides. This requires a targeted application of pesticide on prairie dog burrows which is costly due to the use of pesticide. Even more costly is the labor invested in order to get adequate coverage of the habitat. The second method that has been recently developed is a vaccine laced food source that gives the rodents specific immunity to the disease. The vaccine has been hypothesized to last close to 9 months in prairie dogs, leading to less of a decrease in population size. This is good for the ferrets as their food source remains intact. It does not address the infectious fleas themselves however, so the ferrets are still susceptible to transmission of sylvatic plague.

Ecologically speaking, the sylvatic plague has the potential to be devastating to the grasslands biome. Luckily there is a vaccine available to reduce the mortality rate from its peak of over 90% in prairie dogs. The implementation of vaccine laden foods in prairie dog dense areas will help the entire ecosystem, especially animals that feed directly on the rodents specifically the black footed ferret.


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