Lyme Disease: Increase Could Be Caused By Foxes, Not Deer

Lyme Disease Decreased Fox Population

Lyme disease is expected to be a huge problem this summer, but the explosion of the disease in recent years could actually be attributed to a change in the numbers of foxes and coyotes (and what they eat).

The Milwaukee Journal Sentinel reports that Wisconsin has seen a 280% increase in Lyme disease cases between 1997 and 2007, with a total of 2,376 cases across the state in 2011 alone. Other states in the Midwest and East Cost have seen an even bigger increase.

Lyme disease is typically transferred to humans through ticks, and begins with a distinctive bull’s-eye rash, a bacterial infection that can require extensive antibiotics and can even lead to arthritic and nervous system complications.

MSNBC reports that the study was published on Monday in the Proceedings of the National Academy of Sciences, in which the researchers state:

“Increases in Lyme disease in the Northeastern and Midwestern United States over the past three decades are frequently uncorrelated with deer abundance and instead coincide with a range-wide decline of a key small-mammal predator, the red fox, likely due to expansion of coyote populations.”

One study researcher, Taal Levi, who completed the study as part of his graduate work at the University of California, Santa Cruz, stated:

“We found that where there once was an abundance of red foxes, there is now an abundance of coyotes.”

Dr. Levi has found two different things. The first discovery is that deer aren’t significant transmitters of the bacteria that causes Lyme disease, B. burgdorferi, because their systems usually flush it quickly. Some mice, however, tend not to clear the bacteria at all. The second thing he noticed, according to The New York Times, was that coyote populations seem to slowly be driving out foxes, and coyote population density is much less than foxes, meaning that mice and other prey they usually feed on have less of a chance to be made into a meal.

With this study, Dr. Levi was able to show that one big factor for increasing Lyme disease cases is the decline in the fox population.

Check out more information about Lyme disease here: