Southern tick-associated rash illness

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: : Vishnu Vardhan Serla M.B.B.S. [2]

A rash similar to the rash of Lyme disease has been described in humans following bites of the lone star tick, Amblyomma americanum. The rash may be accompanied by fatigue, fever, headache, muscle and joint pains. This condition has been named southern tick-associated rash illness (STARI). The cause of STARI is not known.

The cause of STARI is unknown. Studies have shown that is not caused by Borrelia burgdorferi, the bacterium that causes Lyme disease. Another spirochete, Borrelia lonestari, was detected in the skin of one patient and the lone star tick that bit him. However, subsequent study of over two dozen STARI patients has found no evidence of B. lonestari infection.

STARI is specifically associated with bites of Amblyomma americanum, known commonly as the lone star tick.

STARI is diagnosed on the basis of symptoms, geographic location, and possibility of tick bite. Because the cause of STARI is unknown, no diagnostic blood tests have been developed.

It is not known whether antibiotic treatment is necessary or beneficial for patients with STARI. Nevertheless, because STARI resembles early Lyme disease, physicians will often treat patients with oral antibiotics.

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: : Vishnu Vardhan Serla M.B.B.S. [2]

Most ticks go through four life stages: egg, six-legged larva, eight-legged nymph, and adult. After hatching from the eggs, ticks must eat blood at every stage to survive. Ticks that require this many hosts can take up to 3 years to complete their full life cycle, and most will die because they don’t find a host for their next feeding.

Ticks can feed on mammals, birds, reptiles, and amphibians. Most ticks prefer to have a different host animal at each stage of their life, as shown below:

Ticks find their hosts by detecting animals´ breath and body odors, or by sensing body heat, moisture, and vibrations. Some species can even recognize a shadow. In addition, ticks pick a place to wait by identifying well-used paths. Then they wait for a host, resting on the tips of grasses and shrubs. Ticks can’t fly or jump, but many tick species wait in a position known as “questing”.

While questing, ticks hold onto leaves and grass by their third and fourth pair of legs. They hold the first pair of legs outstretched, waiting to climb on to the host. When a host brushes the spot where a tick is waiting, it quickly climbs aboard. Some ticks will attach quickly and others will wander, looking for places like the ear, or other areas where the skin is thinner.

The lone star tick, Amblyomma americanum, is found throughout the eastern, southeastern and south-central states. The distribution, range and abundance of the lone star tick have increased over the past 20-30 years, and lone star ticks have been recorded in large numbers as far north as Maine and as far west as central Texas and Oklahoma. All three life stages (larva, nymph, adult) of the lone star tick will feed on humans, and may be quite aggressive. Lone star ticks will also feed readily on other animals, including dogs and cats, and may be brought into the home on pets. The saliva from lone star ticks can be irritating; redness and discomfort at a bite site does not necessarily indicate an infection.

Ticks transmit pathogens that cause disease through the process of feeding.

• Depending on the tick species and its stage of life, preparing to feed can take from 10 minutes to 2 hours. When the tick finds a feeding spot, it grasps the skin and cuts into the surface.
• The tick then inserts its feeding tube. Many species also secrete a cement-like substance that keeps them firmly attached during the meal. The feeding tube can have barbs which help keep the tick in place.
• Ticks also can secrete small amounts of saliva with anesthetic properties so that the animal or person can’t feel that the tick has attached itself. If the tick is in a sheltered spot, it can go unnoticed.
• A tick will suck the blood slowly for several days. If the host animal has a bloodborne infection, the tick will ingest the pathogens with the blood.
• Small amounts of saliva from the tick may also enter the skin of the host animal during the feeding process. If the tick contains a pathogen, the organism may be transmitted to the host animal in this way.
• After feeding, most ticks will drop off and prepare for the next life stage. At its next feeding, it can then transmit an acquired disease to the new host.

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: : Vishnu Vardhan Serla M.B.B.S. [2]

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The cause of STARI is unknown. Studies have shown that is not caused by Borrelia burgdorferi, the bacterium that causes Lyme disease. Another spirochete, Borrelia lonestari, was detected in the skin of one patient and the lone star tick that bit him. However, subsequent study of over two dozen STARI patients has found no evidence of B. lonestari infection.

STARI is specifically associated with bites of Amblyomma americanum, known commonly as the lone star tick.

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: : Vishnu Vardhan Serla M.B.B.S. [2]

Many people, even health care providers, can be confused about whether the lone star tick causes Lyme disease. It does not. Patients bitten by lone star ticks will occasionally develop a circular rash similar to the rash of early Lyme disease. The cause of this rash has not been determined; however, studies have shown that the rash is not caused by Borrelia burgdorferi, the bacterium that causes Lyme disease.

In a study that compared physical findings from STARI patients in Missouri with Lyme disease patients in New York (Wormser et al, 2005), several key differences were noted:

• Patients with STARI were more likely to recall a tick bite than were patients with Lyme disease.
• The time period from tick bite to onset of the skin lesion was shorter among patients with STARI (6 days, on average).
• STARI patients with an erythema migrans rash were less likely to have other symptoms than were Lyme disease patients with erythema migrans rash.
• STARI patients were less likely to have multiple skin lesions, had lesions that were smaller in size than Lyme disease patients (6-10 cm for STARI vs. 6-28 cm for Lyme disease), and had lesions that were more circular in shape and with more central clearing.
• After antibiotic treatment, STARI patients recovered more rapidly than did Lyme disease patients.

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: : Vishnu Vardhan Serla M.B.B.S. [2]

STARI is specifically associated with bites of Amblyomma americanum, known commonly as the lone star tick. Lone star ticks can be found from central Texas and Oklahoma eastward across the southern states and along the Atlantic coast as far north as Maine. The adult female is distinguished by a white dot or “lone star” on her back. All three life stages of A. americanum aggressively bite people.

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