Lyme Disease And English Ivy

English Ivy, haven for ticks
English Ivy killing a stand of pine

English Ivy is not only killing trees across the country, and especially on Long Island, where homeowners, businesses, and municipalities are letting it run rampant, it is also helping to spread Lyme Disease and other tick borne illnesses.

English Ivy Killing Some Oaks

Before we talk of Lyme Disease, however, let’s first note just how destructive English Ivy is to our forests and trees. It steals light and water that would go to the tree, and it weakens the bark, opening the way to fungal infection. The Ivy spreads along the ground from tree to tree of course, but birds also eat their berries, then poop them out miles away, at the edge of a forest often.

Please if you have English Ivy on your property, get rid of it. I know, easier said than done. The first step is to cut the English Ivy all around the base of the tree. Here is a simple guide for removal. All that is growing up the tree will in time whither away, and maybe you just saved a tree. English Ivy is invasive. It has no insect enemies, and so spreads uncontested. And it is destroying our native habitats.

There is now a more urgent reason why we need to eradicate English Ivy. It turns out that English Ivy provides ground cover for the White-Footed Mouse, the major carrier of Lyme Disease and other tick borne illnesses.

lyme disease
White Footed Mouse (Peromyscus Leucopus)

Our birds of prey — our owls, our hawks — can’t hunt well under those conditions. That’s true of our cats as well. As a consequence, we have seen an explosion of Lyme Disease on Long Island. The White Footed Mouse is the principle cause. THEY INFECT THE TICKS!!!

White-footed mice are the principal natural reservoirs for Lyme disease bacteria. Ticks that feed on mice are highly likely to become infected, making them capable of transmitting Lyme disease to people during their next blood meal. “

The conclusion seems obvious. If we want to reclaim our woods and open spaces, if we want to walk them without fear, we need to put a serious dent in The White Footed Mouse population. To do this, we would want to focus on the “buffer zones” the edge of the woods, right where the English Ivy is most prevalent, and where the deer leave the forest to graze. This is also where we will find people — at the wood’s edge. By clearing ivy from along roadways and from vacant lots, municipalities would be addressing a large and growing public health issue — Lyme Disease.

Ironically, the deer that helped the tick population grow and spread do not become infected with the Lyme disease bacterium and cannot cause infection in ticks. But, birds and small mammals, particularly the abundant white-footed mouse, can carry the bacteria and infect immature ticks that feed on them. Infected larvae turn into infected nymphs, the source of infection for larger animals and humans.

Adult ticks hitchhike a ride on the deer, where they mate and feed on the deer’s blood. When they are done, the female then drops off into the leaf litter where deer travel and lays her eggs. Each deer can support hundreds of ticks, and each female tick lays about 2,000 eggs.

Bottom line: The deer do not carry Lyme Disease. The already infected ticks merely feed off them. We are in a situation now where half of all ticks on Long Island carry Lyme Disease and 70% of the people infected were bitten in their own yards, and the English Ivy we often see covering the ground provides the mice with all the cover they need.

Given the science, how should Suffolk and Nassau County seek to address this problem? Making The White Footed Mouse easier prey by removing invasive underbrush, particularly English Ivy, would be the way. Since 70% are bitten right in their yards, we should look at where in our yards we have created havens for these rodents.

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