What is Lyme disease?

Lyme disease is caused by four main species of bacteria spread by ticks. They are:

  • Borrelia burgdorferi
  • Borrelia mayonii
  • Borrelia afzelii
  • Borrelia garinii

The leading cause of Lyme disease in the United States are Borrelia burgdorferi and Borrelia mayonii, while Borrelia afzelii and Borrelia garinii are the leading causes in Europe and Asia. The most common tick-borne illness in these regions, Lyme disease is transmitted by the bite of an infected black-legged tick, commonly known as a deer tick.

Typical symptoms include fever, headache, fatigue and a characteristic skin rash called erythema migrans. If left untreated, the infection can spread to the joints, the heart and the nervous system.

Here are 10 facts you should know about Lyme disease.

  1. Lyme disease is caused by bacteria that is only transmitted to humans when they are bitten by an infected tick.
  2. A tick typically must be attached to the skin for at least 36 hours to infect its host.
  3. Most cases of Lyme disease occur in late spring and early summer.
  4. The most common symptoms of Lyme disease include a red, circular “bulls-eye” rash, fatigue, neck stiffness or pain, jaw discomfort, muscle pain, joint aches like arthritis- typically in the knees, swollen glands, memory loss, cognitive confusion, vision problems, digestive issues, headaches and fainting. About 70-80% of people infected develop the rash, which shows up several days to weeks after the tick bite.
  5. Lyme disease is diagnosed by medical history, physical exam and sometimes a blood test. It may take 4-6 weeks for the human immune system to make antibodies against the bacteria and therefore show up in a positive blood test. That is why it is usual for patients with the Lyme rash to usually have a negative blood test and diagnosis has to be based on the characteristic appearance of the rash. Anyone who has symptoms for longer than six weeks and who has never been treated with antibiotics is unlikely to have Lyme disease if the blood test is negative.
  6. Most cases of Lyme disease are successfully treated with a few weeks of antibiotics. 
  7. Tick-borne diseases have been reported in all 48 contiguous states and Alaska, though the majority are focused in the Northeast and Midwest. 25% of the reported cases are children. Lyme disease has been found on every continent but Antarctica.
  8. Researchers didn’t identify the cause of Lyme disease and connect it with ticks until 1981. The bacterium that causes the disease is named in honor of Willy Burgdorfer, the scientist who made the connection.
  9. In 2016 there were over 58,000 cases of Lyme disease reported in the United States. Cases of vector borne diseases from ticks and mosquitos have tripled since 2004.
  10. The best treatment for Lyme disease is prevention:
    - Be cautious in the woods, avoid bushy and grassy areas.
    - Wear long pants and long-sleeved shirts
    - Wear insect repellent containing DEET on exposed skin
    - After walking in wooded areas, thoroughly check the skin for the poppy-seed sized ticks, paying particular attention to the scalp, armpits and groin. If you find a tick, carefully remove it with tweezers.