The tick responsible for Lyme disease in the USA
November 2nd, 2010This tiny little tick is the one responsible for spreading Lyme disease. It is called the blacklegged tick, and is also known as the Lyme disease tick, by virtue of being the carrier of this disease. As can be seen from the photo of the black legged tick below, its markings are quite obvious.
However, the lyme disease tick in the USA comprises two ticks:
The Ixodes scapularis tick of the Eastern USA, and the Ixodes pacificus tick of the western USA.
Both these lyme disease ticks look pretty much the same and are both called the blacklegged tick.
Although popularly referred to as insects, the lyme disease tick has 8 legs, and is therefore an arachnid, like a spider is.
So, how do you know if the tick that bit you is a lyme disease tick?
It’s size, but mostly it’s appearance is the big give away:
The lyme disease tick has a pronounced darker area around the top half or more of it’s body, the other two ticks do not.
The Life Cycle of the Lyme disease tick:
AS you can see from this lovely picture of the lyme disease tick lifecycle, the eggs and larva are not considered to be greatly infectious for lyme disease. Rather, it is only when the lyme disease tick is in the nymph stage that they pose the greatest real risk to humans – presumably because, as adults, it is no longer feeding to grow.
Essentially any animal can act as a host for the lyme disease tick, including robbins, deer, foxes, mice … Come autumn and winter, and the lyme disease tick poses little risk of infection.
How do you remove a tick?
Carefully, as you don’t want to leave the head attached into your skin, which can easily happen if you yank on the body.
So, with a pair of fine, pointy tweezers, you grasp the tick around the head region, and lift it up off the skin steadily. This can be a bit of a challenge given the small size of a lyme disease tick, and the way it sticks its head into your skin.
Should we coat the tick with vaseline or try burning it or do something else to it? The CDC says not to do anything to the tick prior to its removal, as you could cause the tick to inject more saliva into you, thereby increasing your risk of catching lyme disease etc.
Why is the removal of the head from the skin so important?
I believe it is because that when a tick feeds, it does so by a tube it inserts into the skin, and the blood then flows up the tube into its body. The problem is that blood animals have blood that coagulates to seal off breaks in the blood vessels and capilleries. So, the blood coagulates to prevent the tick from from taking the blood. In order to get round this, the tick automatically excretes it’s saliva into the blood vessel to prevent the blood from coagulating at that point. It is believed, that via this saliva, the lyme disease is carried into the human body. So, if you remove the tick body and leave the head, the first thing your leaving there is the tube and head that are responsible for the saliva being pumped in in the first place.
Secondly, infection can set in where the tick head is left behind.
Thirdly, if you grasp the tick round the body, your likely to force more saliva from the tick into you, and increase the risk of catching lyme disease from it, if the tick is likewise infected.
Maps, diagrams, drawings and photos courtesy of www.cdc.com. You may also find http://www.anaes.med.usyd.edu.au/venom/spiders.html a useful page on tick removal.



































