Author:
Jonathan A.Edlow
Description
Even in high endemic areas for tick-borne diseases, the risk of infection with a tick-borne pathogen is very low. After a tick bite, patient concerns include:
- Tick removal
- Local effect of the bite
- Possibility of acquiring a tick-borne illness:
- Fear of contracting Lyme disease
- Desire to be tested or treated for Lyme
Etiology
- Specific tick-borne infections are discussed in other chapters
- Tick bite can be from different species of ticks of 2 major types:
- Soft ticks (Ornithodoros):
- Causes tick-borne relapsing fever
- Only feed for minutes and therefore almost never provoke a visit to the ED
- Hard ticks - especially Ixodes and Dermacentor:
- Feed for several days to a week and therefore, more likely to be noticed by patient and lead to an ED visit
- Lyme disease transmission:
- Species of tick, stage of development, duration of attachment, and geography may all play a role in the possibility of developing Lyme disease
- Most cases of Lyme are associated with bites from nymphal Ixodes scapularis ticks
- Most cases of Lyme are transmitted only after the tick has been attached for 24-48 hr:
- Degree of engorgement is a marker for duration of attachment
Signs and Symptoms
Tick is attached to skin
History
- The patient usually has made the diagnosis themselves, although sometimes they mistake the tick for skin tags or other skin lesions (or vice versa)
- Determine the duration of tick attachment, as this may influence the decision to prescribe antibiotic prophylaxis
Physical Exam
Directly examine the skin and the tick:
- Try to identify the tick species
- Estimate degree of engorgement
ALERT |
- Some tick-borne infections are potentially fatal. Because there are no confirmatory diagnostic tests that are available in real time, they must be diagnosed based on history, physical, and epidemiologic context
- Because the drug of choice for some of these infections - doxycycline - is not usually prescribed for empiric therapy for acutely ill febrile patients, ask about the potential for tick bites in the history of febrile patients and consider using this drug in the appropriate settings
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Essential Workup
Accurate history and physical exam searching for presence of tick
Diagnostic Tests & Interpretation
Lab
- Testing for Lyme disease is not indicated:
- Such antibody testing would only reflect prior exposure to Borrelia burgdorferi
- No treatment implications whatsoever for the current bite
Diagnostic Procedures/Surgery
- Testing of the tick itself is not recommended
- See treatment for tick removal
Differential Diagnosis
- Tick-borne diseases in North America:
- Lyme disease
- Other Lyme-like diseases such as Southern tick-associated rash illness (STARI) and Borrelia miyamotoi infection
- Babesiosis
- Anaplasmosis (formerly ehrlichiosis)
- Rocky Mountain spotted fever (RMSF)
- Relapsing fever
- Tularemia
- Colorado tick fever
- Q-fever
- Tick-borne encephalitis (Powassan fever)
- Tick paralysis
- Additional tick-borne diseases found in Europe:
- Tick-borne encephalitis
- Boutonneuse fever (Rickettsia conorii)
- Other spotted fever rickettsiae
Initial Stabilization/Therapy
Remove tick:
- Early removal reduces the likelihood of transmission of tick-borne infections
ED Treatment/Procedures
- Tick removal method:
- Grasp the tick with very fine forceps, as close to the skin as possible, and gently lift up over 30-120 s
- Most ticks will come out
- Do not squeeze the tick, which could inject infectious materials into the patient's skin
- If mouthparts are left in the skin, although this could lead to local infection or foreign body reaction, it has no implications for transmission of tick-borne diseases
- Another described method:
- Inject an intradermal wheal of lidocaine with epinephrine beneath the tick
- Tick may crawl out of its own accord
- Methods not to use include:
- Burning the tick with a match
- Covering it with petroleum jelly or other noxious agents
- Lyme disease prophylaxis:
- Indicated if the tick is an engorged I. scapularis nymph is found within 72 hr of the bite, or if the physician decides to prophylax
- Doxycycline 200 mg for 1 dose
- For children, there is no studied single-dose regimen:
- Prescribe amoxicillin (25-50 mg/kg) for 10 d in divided doses
- No data support prophylactic antibiotics for other tick-borne diseases
Pediatric Considerations |
- Several studies used 10 d of amoxicillin in children for prevention of Lyme disease
- No patients in the treated groups developed Lyme or seroconverted
- Although courses <10 d have not been studied, given the adult data, fewer days probably are effective after a tick bite to prevent Lyme disease
- Tick paralysis is a rare disease but usually occurs in children, especially in girls with long hair; never diagnose Guillain-Barre syndrome without doing a thorough inspection of the entire body, especially the scalp, for ticks
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Pregnancy Prophylaxis |
| Although there are no high quality data on antibiotic prophylaxis for Lyme disease in pregnant women, some authors recommend having a very low threshold for treating pregnant women with tick bites (using amoxicillin). |
Medication
- Amoxicillin: 25-50 mg/kg in div doses t.i.d for 10 d
- Doxycycline: 200 mg PO for 1 dose
Disposition
Admission Criteria
- Tick bite with symptoms or signs of tick paralysis or in patients who have an established tick-borne disease which is severe (e.g., hypotension or sepsis)
- Tick bite leading to systemic infection sufficiently severe to require admission (e.g., RMSF, anaplasmosis, babesiosis [especially in a splenectomized patient]).
Discharge Criteria
All other patients, the vast majority, are safely discharged
Follow-up Recommendations
- Follow-up with primary care physicians if there are issues regarding local bacterial infection from the bite (cellulites) or subsequent symptoms and signs of 1 of the tick-borne infections listed above
- Seek medical attention in the event of a febrile illness and report the history of the tick bite to that physician
- Patients who have been bitten by ticks should be counseled about future tick bite prevention, including potential use of DEET to the skin and permethrin-treated clothing
- EdlowJA. Introduction to tick-borne diseases. In: Emergency Medicine On-Line Textbook. Boston, MA: Medical Publishing Corporation; 1997, updated 2005.
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- KrausePJ, NarasimhanS, WormserGP, et al. Human Borrelia miyamotoi infection in the United States . N Engl J Med. 2013;368:291-293.
- MillerNJ, RainoneEE, DyerMC, et al. Tick bite protection with permethrin-treated summer-weight clothing . J Med Entomol. 2011;48(2):327-333.
- NadelmanRB, NowakowskiJ, FishD, et al. Prophylaxis with single-dose doxycycline for the prevention of Lyme disease after an Ixodes scapularis tick bite . N Engl J Med. 2001;345:79-84.
- NeedhamGR. Evaluation of five popular methods for tick removal . Pediatrics. 1985;75:997-1002.
- SoodSK, SalzmanMB, JohnsonBJ, et al. Duration of tick attachment as a predictor of the risk of Lyme disease in an area in which Lyme disease is endemic . J Infect Dis. 1997;175:996-999.
- TibblesCD, EdlowJA. Does this patient have erythema migrans?JAMA. 2007;297:2617-2627.
- Tijsse-KlasenE, JacobsJJ, SwartA, et al. Small risk of developing symptomatic tick-borne diseases following a tick bite in the Netherland s . Parasit Vectors. 2011;4:17.
- WarshafskyS, LeeDH, FrancoisLK, et al. Efficacy of antibiotic prophylaxis for the prevention of Lyme disease: An updated systematic review and meta-analysis . J Antimicrob Chemother. 2010;65:1137-1144.
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