Amblyomma americanum

style="background:#Template:Taxobox colour;"|Lone star tick
style="background:#Template:Taxobox colour;" | Scientific classification
Kingdom: Animalia Phylum: Arthropoda Class: Arachnida Subclass: Acari Order: Ixodida Family: Ixodidae Genus: Amblyomma Species: A. americanum
Binomial name
Amblyomma americanum (Linnaeus, 1758)
Red indicates where the species is normally found; Blue indicates other locations where the species has been reported Red indicates where the species is normally found; Blue indicates other locations where the species has been reported

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Overview

Amblyomma americanum, or lone star tick, is a species of tick in the genus Amblyomma.

Life Cycle

General Tick Life Cycle

This image displays an example of the tick lifecycle, based on stages and the months that they are most likely to occur during.

• A tick's life cycle is composed of four stages: hatching (egg), nymph (six legged), nymph (eight legged), and an adult.
• Ticks require blood meal to survive through their life cycle.
• Hosts for tick blood meals include mammals, birds, reptiles, and amphibians. Ticks will most likely transfer between different hosts during the different stages of their life cycle.
• Humans are most often targeted during the nymph and adult stages of the life cycle.
• Life cycle is also dependent on seasonal variation.
• Ticks will go from eggs to larva during the summer months, infecting bird or rodent host during the larval stage.
• Larva will infect the host from the summer until the following spring, at which point they will progress into the nymph stage.
• During the nymph stage, a tick will most likely seek a mammal host (including humans).
• A nymph will remain with the selected host until the following fall at which point it will progress into an adult.
• As an adult, a tick will feed on a mammalian host. However unlike previous stages, ticks will prefer larger mammals over rodents.
• The average tick life cycle requires three years for completion.
  • Different species will undergo certain variations within their individual life cycles.

Spread of Tick-borne Disease

• Ticks require blood meals in order to progress through their life cycles.
• The average tick requires 10 minutes to 2 hours when preparing a blood meal.
• Once feeding, releases anesthetic properties into its host, via its saliva.
• A feeding tube enters the host followed by an adhesive-like substance, attaching the tick to the host during the blood meal.
• A tick will feed for several days, feeding on the host blood and ingesting the host's pathogens.
• Once feeding is completed, the tick will seek a new host and transfer any pathogens during the next feeding process.

Distribution

It is very widespread in the United States ranging from Texas to Iowa in the Midwest and east to the coast where it can be found as far north as Maine. It is most common in wooded areas, particularly in forests with thick underbrush, and large trees.

Development

The tick follows the normal development stages, egg, larva, nymph and adult.

Vector

Like all ticks, it can be a vector of diseases including human monocytotropic ehrlichiosis (Ehrlichia chaffeensis), canine and human granulocytic ehrlichiosis (Ehrlichia ewingii), tularemia (Francisella tularensis), and southern tick-associated rash illness (STARI, possibly caused by the spirochete Borrelia lonestari). STARI exhibits a rash similar to that caused by Lyme disease, but is generally considered to be less severe.

Though the primary bacterium responsible for Lyme disease, Borrelia burgdorferi, has occasionally been isolated from lone star ticks, numerous vector competency tests have demonstrated that this tick is extremely unlikely to be capable of transmitting Lyme disease. Some evidence indicates A. americanum saliva inactivates B. burgdorferi more quickly than the saliva of Ixodes scapularis. Recently the bacteria Borrelia andersonii and Borrelia americana have been linked to Amblyomma americanum.

In response to two cases of severe febrile illness occurring in two farmers in northwestern Missouri, researchers determined the lone star tick can transmit the heartland virus in 2013. Six more cases were identified in 2012–2013 in Missouri and Tennessee.

Meat allergy

The bite of this tick can cause a person to develop a meat allergy to nonprimate mammalian meat and meat products. This allergy is characterized by adult onset, and a delayed reaction of urticaria or anaphylaxis appearing 4–8 hours after consumption of the allergen. The allergen has been identified as a carbohydrate called galactose-α-1,3-galactose (alpha gal). As well as occurring in nonprimate mammals, alpha gal is also found in cat dander and a drug used to treat head and neck cancer. Commercial tests for alpha gal IgE became available following research.

Bibliography

• Piesman J, Sinsky RJ., Ability of Ixodes scapularis, Dermacentor variabilis, and Amblyomma americanum (Acari: Ixodidae) to acquire, maintain, and transmit Lyme disease spirochetes (Borrelia burgdorferi) ; J Med Entomol. 1988 September; 25(5):336-9.

External links

• http://www.k-state.edu/parasitology/625tutorials/Tick03.html

Gallery

• Common name: lone star tick
• Scientific name: Amblyomma americanum
• Reservoir: birds and deer (larvae and nymphs); white-tailed deer (adult ticks)
• Geographic distribution: southeastern and eastern United States
• Disease transmitted: ehrlichiosis, tularemia, southern tick-associated rash illness

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  Lone star tick (Amblyomma americanum)
  Adapted from CDC

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  Approximate distribution of the lone star tick
  Adapted from CDC