Ixodes scapularis

style="background:#Template:Taxobox colour;"|Ixodes scapularis
style="background:#Template:Taxobox colour;" | Scientific classification
Kingdom: Animalia Phylum: Arthropoda Subphylum: Chelicerata Class: Arachnida Subclass: Acari Superorder: Parasitiformes Order: Ixodida Family: Ixodidae Genus: Ixodes Species: I. scapularis
Binomial name
Ixodes scapularis
File:Ixodes scapularis range map.svg

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [2]

Overview

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. 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, Powassan virus disease, etc.) and is known as the deer tick owing to its habit of parasitizing the white-tailed deer. It is also known to parasitize mice, lizards, migratory birds, etc. especially while the tick is in the larva or nymph stage.

Description

• 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
• 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.
• 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 below).

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Behavior

• I. scapularis has a two-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.
• Deer are the preferred host of the deer tick, but it is also known to feed on small rodents.
• After she 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.
• Transtadial (between tick stages) passage of Borrelia burgdorferi is common. Vertical passage (from mother to egg) of Borrelia is uncommon.

• I. scapularis may be active even after a moderate to severe frost, as daytime temperatures 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 Transmitted Diseases

• Ixodes scapularis is the main vector of Lyme disease in North America. It can also transmit other Borrelia species, including Borrelia miyamotoi.

• Other parasitic organism transmitted by I. scapularis include:
• Theileria microti a parasitic organism responsible for Babesiosis.
• Anaplasma phagocytophilum the bacterial infection responsible for human granulocytic anaplasmosis (HGA).
• Among early Lyme disease patients, depending on their location, 2%–12% will also have HGA and 2%–40% will have babesiosis.

• 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's emerging infectious diseases department did a study in rural New Jersey of 100 ticks, and found 55% of the ticks were infected with at least one of the pathogens.

Predators

• Guineafowl, chickens, and fire ants are known predators of ticks. None has been proven to be effective in populations on a large scale, but anecdotal evidence supports localized control of tick populations.
• Although they are the preferred mammalian hosts, deer cannot transmit Borrelia spirochetes to ticks. Ticks acquire Lyme disease microbes by feeding on infected mice and other small rodents.

Genome sequencing

• Genomic information

  NCBI genome ID	523
  Ploidy	diploid
  Genome size	1,765.38 Mb
  Number of chromosomes	15 pairs
  Year of completion	2008

  The genome of I. scapularis has been sequenced.

External links

• Information on Tick-Related Health Threats and Deer Tick Fact Sheet from the National Pest Management Association
• blacklegged tick, Ixodes scapularis on the UF / IFAS Featured Creatures Web site
• Ixodes scapularis, black-legged tick, deer tick overview as a vector for Lyme disease, developmental stages at MetaPathogen
• Ixodes scapularis genome sequence at VectorBase
• Powassan Virus: Transmission on the Centers for Disease Control and Prevention website.

Please read to protect yourself from Deer ticks that may cause Lyme disease. Public Health Fact Sheet: Lyme Disease

Gallery

• Common name: blacklegged tick, deer tick
• Scientific name: Ixodes scapularis
• Reservoir: small mammals and birds (larvae and nymphs); rodents and mammals (adult ticks)
• Geographic distribution: northeastern and upper midwestern United States
• Disease transmitted: anaplasmosis, babesiosis, Lyme disease

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  Approximate distribution of the Blacklegged tick
  Adapted from CDC