From the Guidelines
If you've developed an erythema migrans rash after a tick removal, you should seek immediate medical treatment with doxycycline 100mg twice daily for 10-14 days, which is the first-line treatment for Lyme disease, as recommended by the Infectious Diseases Society of America 1.
Treatment and Testing
Testing should be done at the initial visit, typically with a two-tier testing approach that includes an ELISA test followed by a Western blot if positive, however, treatment should not be delayed while waiting for test results if the rash is present, as this is diagnostic for Lyme disease 1.
- The erythema migrans rash is a hallmark sign of Lyme disease, appearing as an expanding red ring or bull's-eye pattern at the site of the tick bite, usually within 3-30 days after the bite.
- Prompt treatment is essential to prevent progression to more serious complications affecting the joints, heart, and nervous system.
Follow-up Testing
Follow-up testing may be recommended 4-6 weeks after the initial visit if the first test was negative or inconclusive, as antibodies may take time to develop 1.
- In patients with potential tick exposure in a Lyme disease endemic area who have 1 or more skin lesions compatible with erythema migrans, clinical diagnosis rather than laboratory testing is recommended 1.
- In patients with 1 or more skin lesions suggestive of, but atypical for erythema migrans, antibody testing performed on an acute-phase serum sample (followed by a convalescent-phase serum sample if the initial result is negative) rather than currently available direct detection methods such as polymerase chain reaction (PCR) or culture performed on blood or skin samples is suggested 1.
Key Considerations
- Doxycycline is relatively contraindicated in pregnant women and children < 8 years old, and alternative treatments such as amoxicillin or cefuroxime axetil may be considered in these cases 1.
- The patient should be monitored closely for signs and symptoms of tickborne diseases for up to 30 days after the tick bite, and should be advised to seek medical attention immediately if they develop any symptoms such as fever, headache, or joint pain 1.
From the Research
Erythema Migrans Rash After Tick Removal Treatment and Testing
- The erythema migrans rash is a characteristic skin lesion that appears in the early stage of Lyme disease, usually within two weeks after a bite from an infected tick 2.
- The rash is typically ring-shaped and expands outwards from the bite site, and its appearance can vary, with some cases presenting with central erythema, central clearing, or central purpura 3.
- Diagnosis of erythema migrans is based on clinical findings, and serological tests are not useful at this stage of the infection 2, 3, 4.
Treatment and Follow-up
- Treatment of erythema migrans can be accomplished with 20 days of oral doxycycline, amoxicillin, or cefuroxime axetil 3.
- A network meta-analysis found that oral amoxicillin, oral azithromycin, injectable ceftriaxone, and injectable cefotaxime were effective for treating Lyme disease, including erythema migrans 5.
- Doxycycline and tetracycline have been compared in the treatment of Lyme disease associated with erythema migrans, with no significant difference in efficacy or safety found between the two 6.
- A 14-day course of doxycycline was found to be comparable to a 20-day course in terms of adverse effects and clinical outcome 6.
Testing and Monitoring
- Serologic testing is not indicated for patients with erythema migrans, as the result is usually negative initially 3.
- Patients with erythema migrans should be monitored for signs of infection progression, and antibiotic treatment should be prescribed if necessary 2.
- Routine antibiotic prophylaxis is not justified after a tick bite, even in an endemic area, as the risk of infection is low 2.