(See also Spirochetes: Lyme Disease, see Rickettsiae and Related Organisms, and Extraintestinal Protozoa: Babesiosis.)

Most tick bites in the US are from various species of Ixodidae, which attach and feed for several days if not removed. Disease transmission is the main concern and becomes more likely if ticks are attached for a longer duration.

Tick bites most often occur in spring and summer and are painless. The vast majority are uncomplicated and do not transmit disease. However, they often cause a red papule at the bite site and may induce hypersensitivity or granulomatous foreign body reactions. The bites of Ornithodoros coriaceus ticks (pajaroello) cause local vesiculation, pustulation with rupture, ulceration, and eschar, with varying degrees of local swelling and pain. Similar reactions have resulted from bites of other ticks.

Diagnosis

Diagnosis is by clinical evaluation and identification of the attached tick.

Treatment

• Tick removal with blunt, curved forceps
• Sometimes prophylactic doxycycline

Ticks should be removed as soon as possible to reduce the cutaneous immune response and the likelihood of disease transmission. If the patient presents with the tick still attached, the best method of extracting the tick and all of its mouth parts from the skin is by using a blunt forceps with medium-sized, curved tips. The forceps should be placed parallel to the skin to grasp the tick's mouth parts firmly as close to the skin as possible. Care should be taken to avoid puncturing the patient's skin and the tick's body. The forceps should be pulled slowly and steadily, directly away from the skin without twisting. Curved-tip forceps are best because the outer curve can be laid against the skin while the handle remains far enough from the skin to grasp easily. Tick mouth parts that remain in the skin and are readily visible should be removed carefully. However, if the presence of mouth parts is questionable, attempts at surgical removal may cause more tissue trauma than would occur if the parts are left in the skin; leaving mouth parts in the skin does not affect disease transmission and, at most, prolongs irritation. Other methods of tick removal, such as burning it with a match (which can damage the patient's tissues) or covering it with petroleum jelly (which is ineffective), are not recommended.

After tick removal, an antiseptic should be applied. If local swelling and discoloration are present, an oral antihistamine may be helpful. Although rarely practical, the tick may be saved for laboratory analysis to check for etiologic agents of tick-borne disease in the geographic area where the patient acquired the tick.

Pajaroello tick lesions should be cleaned, soaked in 1:20 Burow's solution, and debrided when necessary. Corticosteroids are helpful in severe cases. Infections are common during the ulcer stage but rarely require more than local antiseptic measures.

Lyme disease prophylaxis

A single dose of doxycycline (200 mg for adults and 4 mg/kg to a maximum of 200 mg for children ≥ 8 yr) should be considered when all of the following criteria are met:

• The tick is an adult or nymphal Ixodes scapularis.
• The tick is estimated to have been attached for ≥ 36 h based on degree of engorgement or certainty about time of exposure.
• Prophylaxis can be started within 72 h after the tick was removed.
• The local rate of infection of ticks with Borrelia burgdorferi is ≥ 20%.
• Doxycycline is not contraindicated.

Some experts recommend a longer course of doxycycline (100 mg po bid for 10 to 20 days) to ensure eradication.

Tick Paralysis

Tick paralysis is a rare, ascending, flaccid paralysis that occurs when toxin-secreting Ixodidae ticks bite and remain attached for several days.

In North America, some species of Dermacentor and Amblyomma cause tick paralysis due to a neurotoxin secreted in tick saliva. The toxin is not present in tick saliva during early stages of feeding, so paralysis occurs only when a tick has fed for several days or more. A single tick can cause paralysis, especially if it is attached to the back of the skull or near the spine, but multiple ticks should be sought over the entire body surface.

Symptoms and signs include anorexia, lethargy, muscle weakness, impaired coordination, nystagmus, and ascending flaccid paralysis. Bulbar or respiratory paralysis may develop.

Tick paralysis should be considered in North American patients with acute ascending flaccid paralysis or bulbar paralysis. Differential diagnosis includes Guillain-Barré syndrome, botulism, myasthenia gravis, hypokalemia, and spinal cord tumor.

The paralysis is rapidly reversible with removal of the tick or ticks. If breathing is impaired, O₂ therapy or respiratory assistance may be needed.

Last full review/revision February 2013 by Robert A. Barish, MD, MBA; Thomas Arnold, MD