Lyme Disease Cause and Treatments

Lyme disease is a tick-borne bacterial infection with the potential for widespread systemic effects. It is caused by the bacterium Borrelia burgdorferi (and rarely Borrelia mayonii in the United States) and is transmitted to humans primarily through the bite of infected blacklegged ticks (also known as deer ticks or Ixodes ticks).

Causes and Transmission:

• Blacklegged ticks typically become infected by feeding on infected animals such as mice or deer.
• The tick must usually be attached for 24 hours or more before it can transmit the bacteria to a human host35.
• Lyme disease is most common in the Northeast, mid-Atlantic, and upper Midwest regions of the United States, but cases have been reported throughout the U.S. and in many other countries.

Symptoms:

• Early signs generally appear 3–30 days after the bite. Typical early symptoms include:
  • Erythema migrans: a characteristic expanding red rash, often in a bull’s-eye pattern, seen in about 70–80% of infections.
  • Fever, chills, fatigue, headache, muscle and joint aches, and swollen lymph nodes.
• If untreated, the infection may spread to:
  • Joints (causing arthritis, especially in the knee
  • Heart (Lyme carditis, presenting as irregular heartbeat)
  • Nervous system (including facial palsy, meningitis, numbness, and pain in hands or feet)
• In late or chronic cases, people may experience episodes of joint pain and swelling, shooting pains, tingling in limbs, or cognitive issues.

Diagnosis:

• Clinical diagnosis is based on symptoms, history (especially tick exposure), and physical findings, especially the EM rash.
• Laboratory testing (two-step process: enzyme immunoassay or immunofluorescence assay followed by Western blot) is recommended if symptoms warrant and exposure is likely. Testing is most useful in patients with symptoms lasting several weeks.
• Diagnosis can be complicated if the classic rash is absent.

Treatment:

• Most cases of Lyme disease can be effectively treated with antibiotics—primarily doxycycline, amoxicillin, or cefuroxime.
• Early treatment is most effective. Course typically lasts 2–4 weeks.
• Patients with neurological or cardiac involvement may require intravenous (IV) antibiotics.
• Some patients experience lingering symptoms such as fatigue or joint/muscle aches after treatment, termed Post-Treatment Lyme Disease Syndrome (PTLDS). The cause of PTLDS is not fully understood and extended antibiotic treatment is not recommended.

Prevalence and Public Health:

• Recent CDC estimates suggest that as many as 476,000 people are diagnosed and treated for Lyme disease each year in the United States, but only a fraction of these are officially reported due to underreporting.
• Lyme disease is the most common tick-borne illness in the U.S. and Europe.

Prevention:

• Avoiding tick bites is the best prevention. Recommendations include using insect repellents (such as those containing DEET), wearing long sleeves and pants in tick-infested areas, performing thorough tick checks after outdoor activities, and promptly removing any attached ticks.
• No human Lyme disease vaccine is currently available. A previous vaccine (LYMErix) was discontinued, but clinical trials for new vaccines are ongoing.
• Vaccines do exist for dogs.

Important Caveats:

• Lyme disease can affect anyone exposed to tick habitats, including adults, children, and pets.
• Ticks can carry other diseases besides Lyme disease, so co-infections are possible.
• Chronic Lyme disease or PTLDS remains a controversial subject; there is no scientific consensus supporting prolonged or repeated antibiotic therapy for persistent symptoms.

References:

The above information is synthesized from highly reputable sources including the U.S. Centers for Disease Control and Prevention (CDC), MedlinePlus/National Institutes of Health, Mass.gov, and peer-reviewed medical summaries such as PubMed Central (PMC).