| Ixodes scapularis | |
|---|---|
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Class: | Arachnida |
| Subclass: | Acari |
| Superorder: | Parasitiformes |
| Order: | Ixodida |
| Family: | Ixodidae |
| Genus: | Ixodes |
| Species: | I. scapularis |
| Binomial name | |
| Ixodes scapularis Say, 1821 |
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Ixodes scapularis is commonly known as the deer tick or blacklegged tick (although some people reserve the latter term for Ixodes pacificus, which is found on the West Coast of the USA), and in some parts of the USA as the bear tick[1]. It is a hard-bodied tick (family Ixodidae) of the eastern and northern Midwestern United States. It is a vector for several diseases of animals, including humans (Lyme disease, babesiosis, anaplasmosis, etc) and is known as the deer tick due to its habit of parasitizing the white-tailed deer.
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The image shown at the upper right—and in fact, most images of Ixodes scapularis that are commonly available—show an adult that is unengorged, that is, an adult that has not had a blood meal. This is natural, since the ticks are generally removed immediately upon discovery to minimize the chance of disease. However, the abdomen that holds blood is so much larger when engorged and looks so different from the rest of the tick that it would be easy to assume that an engorged specimen of Ixodes scapularis is an entirely different tick (see photo at left).
When the deer tick has consumed a blood meal its abdomen will be a light grayish-blue color, whereas the tick itself is chiefly black. In identifying an engorged tick it is helpful to concentrate on the legs and upper part of the body.
Ixodes scapularis has a 2 year life cycle, during which time it passes through three stages: larva, nymph, and adult. The tick must take a blood meal at each stage before maturing to the next. Deer tick females latch onto a host and drink its blood for four to five days. After it is engorged, the tick drops off and overwinters in the leaf litter of the forest floor. The following spring, the female lays several hundred to a few thousand eggs in clusters[2]. Transtadial (between tick stages) passage of Borrelia burgdorferi is common. Vertical passage (from mother to egg) of Borrelia is uncommon.
Ticks are very hardy creatures and Ixodes scapularis is no exception. Expect them to be active even after a moderate to severe frost as daytime temps can warm them enough to keep them actively searching for a host. In the spring, they can be one of the first invertebrates to become active. Deer ticks can be quite numerous and seemingly gregarious in areas where they are found.
Ixodes scapularis is the main vector of Lyme disease in North America.[3] It can also transmit other Borrelia species including Borrelia miyamotoi[4].
Ticks that transmit Borrelia burgdorferi to humans can also carry and transmit several other parasites such as Theileria microti and Anaplasma phagocytophilum, which cause the diseases babesiosis and human granulocytic anaplasmosis (HGA), respectively.[5] Among early Lyme disease patients, depending on their location, 2%–12% will also have HGA and 2%–40% will have babesiosis.[6]
Co-infections complicate Lyme symptoms, especially diagnosis and treatment. It is possible for a tick to carry and transmit one of the co-infections and not Borrelia, making diagnosis difficult and often elusive. The Centers for Disease Control (CDC)'s emerging infections diseases department did a study in rural New Jersey of 100 ticks and found that 55% of the ticks were infected with at least one of the pathogens.[7]
Please read to protect yourself from Deer ticks that may cause Lyme disease. http://www.mass.gov/Eeohhs2/docs/dph/cdc/factsheets/lyme.pdf
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