Disease Description (Causes and Symptoms)
- Definition and causes
- Lyme disease is an infection caused mainly by ticks of the genus Ixodes (hard ticks), which serve as vectors. Spirochetes living in the tick’s intestines enter the bloodstream and tissues when the tick bites a person.
- Summary of pathophysiology
- After a local infection, it spreads through the bloodstream or lymphatic system, causing inflammation in multiple organs, including the nervous system, heart, and joints. Depending on the time course of the infection, it may progress from early localized (skin) disease → early disseminated disease (within several weeks) → delayed/chronic joint and neurological symptoms (months to years).
- Main symptoms
- Early stage (days to weeks): typical erythema migrans (a rash that expands outward from the center), fever, chills, headache, muscle aches, and fatigue
- Disseminated stage (several weeks to several months): pain in multiple areas, nervous system involvement (facial paralysis, neuralgia, meningitis-like symptoms), and cardiac involvement (cardiac conduction abnormalities, myocarditis)
- Late stage (months to years): recurrent arthritis (especially of the knee), chronic neurological symptoms (cognitive and memory problems, peripheral nerve symptoms), and persistent fatigue
- Rarely, eye problems (such as uveitis) and severe emotional changes may also occur
Treatment Methods and Precautions
- Standard antibiotic treatment (general principles)
- Early localized disease (erythema migrans): oral doxycycline 100 mg twice daily (adults) or amoxicillin (pregnancy and children) for 10–21 days (depending on the clinical situation, 10–14 days is generally recommended)
- Disseminated disease or severe joint or neurological involvement: oral antibiotics (doxycycline or amoxicillin) for 14–28 days, or intravenous ceftriaxone for 14–28 days in cases of severe disease or central nervous system or cardiac involvement
- Recurrent arthritis (including persistent arthritis after treatment): 28 days of oral therapy; intravenous therapy may be considered if necessary
- Medication selection in special situations
- Pregnancy, breastfeeding, and infants and young children (traditionally, children under 8 years of age): amoxicillin is recommended instead of doxycycline
- In cases of drug allergy or failure to respond to treatment, consult a specialist to select an alternative treatment
- Side effects and precautions
- Antibiotic side effects (gastrointestinal symptoms, photosensitivity, etc.) need to be monitored. Avoid exposure to ultraviolet light when taking doxycycline.
- Some patients may experience prolonged fatigue, pain, cognitive symptoms, and other symptoms after treatment (post-treatment Lyme disease syndrome). The benefits of additional long-term antibiotic treatment are limited; consult a specialist.
- Rarely, a Jarisch–Herxheimer reaction (acute worsening of symptoms early in treatment) may occur, including fever and muscle pain — manage with symptomatic treatment.
- Risk of complications
- If appropriate treatment is delayed, the disease may lead to arthritis, chronic nervous system damage, cardiac complications, and other problems. Rarely, life-threatening complications may occur.
Checklist Before an Outpatient Visit (Including Items to Bring and Example Questions)
- Items to bring (recommended for a doctor’s visit)
- A list of currently used medications (including prescription drugs, over-the-counter medications, and supplements)
- A history of drug allergies and past medical conditions (especially whether you are pregnant; age if the patient is a child)
- When and where the tick bite occurred (if possible, a photo of the preserved tick), and photos of the bite area (if there is a rash, take photos from multiple angles and at different times)
- Notes recording when symptoms began and how they have progressed (the timing, severity, and changes in fever, pain, neurological symptoms, etc.)
- Previous test results (blood tests, imaging, medical records from other hospitals, etc.)
- Useful information to show the doctor during the outpatient visit
- Areas where tick exposure is suspected (history of outdoor activities) and the duration of exposure (estimated attachment time)
- The date symptoms began and how the rash expanded
Examples of General Questions to Ask the Doctor
- What is the expected duration of treatment with this medication, and what are its major side effects?
- When are my symptoms expected to improve after treatment? What are the criteria for recovery?
- Do I need any additional tests during or after treatment (blood tests, neurological examinations, imaging, etc.)?
- If I am pregnant or breastfeeding, or if I have young children, how will medication selection or precautions differ?
- What additional measures are needed if symptoms recur or chronic symptoms develop after treatment?
Examples of Disease-Specific Questions
- Is my skin rash (including the photos) typical erythema migrans, and how do you determine whether serologic testing is needed even without erythema migrans?
- When the time of the tick bite (or the attachment duration) is unknown, what criteria are used to determine whether preventive antibiotic treatment is needed? (For example, the tick species, the prevalence in the area, and the estimated attachment time.)
Additional Tips (Briefly)
- Prevention: When engaging in outdoor activities, use insect repellents (DEET or picaridin), treat clothing with permethrin, wear long clothing and tuck pant legs into socks, and check the entire body for ticks and remove them promptly after returning home (use tweezers to grasp the tick close to the skin and gently pull it straight out).
- Single-dose prophylaxis after exposure (when specific conditions are met): In high-risk areas, if the tick is an Ixodes species and is estimated to have been attached for >36 hours, guidelines recommend considering a single dose of doxycycline 200 mg within 72 hours after exposure; however, whether it should be used depends on local guidelines and the treating doctor’s judgment.