This summer I wrote a number of blog articles on Lyme disease in our area. In them I mentioned that the incidence of Lyme disease has grown enormously in North America. In fact, it is now the most widespread vector-borne illness in the United States. A vector-borne illness is an illness caused by an infectious microbe that is transmitted by blood-sucking arthropods. Some of these that are found in this area are mosquitos, lice, ticks, mites and fleas.
It seems another factor in the growth of this problem is that the areas and geographical ranges have expanded. too. For years, it has been assumed that the growth and geographical spread of the disease was most likely been caused by the rapid recovery of the U.S. deer populations. Deer are a major host of adult blood-sucking ticks. However, some recent studies do not agree with this conclusion.
Recently I read a short article by Rita Capon in Natural History Magazine that caught my eye. It was about a new study on the theory that deer are not responible for the spread of Lyme disease. This article lead me to run for the computer and see what the new studies might say,
The studies instead point to the possibility that the spread may be, in part, caused by the fact that there are now fewer small mammal predators. The main reservoirs of Borrelia burgdorferi, the bacterium causing Lyme disease, are the small mammals the white-footed mouse, the eastern chipmunk, the masked shrew and the short-tailed shrew. Although it may seem hard to believe, many studies indicate that nearly 85% of the ticks causing Lyme disease are infected themselves by these four small mammals.
The various studies also noted that as most gray wolves disappeared from the American scene, coyotes moved in and became the dominant predator all across the country. Because foxes won’t build dens in an area where coyotes reside, the coyote has quickly displaced red foxes in large areas and caused a serious decline in their population and range. In the past, Red-foxes had always been a major predator of all four Lyme disease-causing mammals. The foxes would kill them in large numbers and stash them away for later feeding. While coyotes do kill some of the smaller mammals, they prefer larger prey,such as ground hogs, ducks and even at times small deer.
The studies noted that in areas that still had large populations of red-foxes, Lyme disease was rather rare. One area noted in one particular study included the Allegany National Forest, located in Western New York State, where deer are very plentiful and foxes are abundant. Yet, the study reflected the fact that Lyme disease is rare there. At the same time, the study found that Lyme disease did not consistently increase with an increase in deer population. Ecologist Taal Levi of the University of California believes Lyme disease problem might instead lie in the decline of the red fox, and studies seem to indicate he may be right.
With the increase in the red fox population on Presque Isle, and from I hear all over this region, maybe we can all hope that they will help with the Lyme disease problems here in our corner of Northwestern Pennsylvania.
See you on the park!!
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