Begin Main Content Area

Lyme Disease

Lyme disease is a disease caused by the bacteria Borrelia burgdorferi. It is transmitted by the bite of an Ixodes scapularis tick, also known as a blacklegged tick or deer tick. Lyme disease can cause flu-like symptoms and a rash in the early stages, but can progress to arthritic, neurologic and cardiac symptoms if it is not treated.

What are the symptoms of Lyme Disease?

There are three stages of Lyme disease with distinct signs and symptoms occurring in each stage.

Early Stage (3-30 days after tick bite)

  • Erythema migrans (EM) – red, oval or round rash
    • Although EM is often described as a "bull's eye rash," the bull's eye appearance is not common. The rash may be round or oval with no clearing, it may have a red ring with clearing in the center, it may appear blueish in color. The first EM rash usually appears at the site of the tick bite, but may progress to multiple EM rashes anywhere on the body.
    • Occurs in 70-80% of cases in some form, bull's eye appearance is less common.
    • First EM rash typically appears within 3-30 days, the average is about 7 days.
    • May increase in size to around 12 inches.
    • May feel warm to the touch, but is rarely itchy or painful.
Common appearances of EM

Common appearances of Erythema migrans

  • Fever, chills, headache, muscle and joint pain, swollen lymph nodes. Most Lyme cases in Pennsylvania occur in the late spring and summer months when flu is rare. Lyme and other tickborne diseases should be considered when you have a flu-like illness in the summer.
Later Stage (days to months after tick bite)

  • Severe headaches and neck stiffness
  • Additional EM rashes on other areas of the body
  • Arthritis with severe joint pain and swelling, particularly the knees and other large joints.
  • Facial palsy (loss of muscle tone or droop on one or both sides of the face)
  • Intermittent pain in tendons, muscles, joints, and bones
  • Heart palpitations or an irregular heart beat
  • Episodes of dizziness or shortness of breath
  • Inflammation of the brain and spinal cord
  • Nerve pain
  • Shooting pains, numbness, or tingling in the hands or feet
  • Problems with short-term memory

How is Lyme disease diagnosed?

Lyme disease is diagnosed through a blood test. Your blood samples will be sent to a lab which will run a screening test. The screening test looks for antibodies to Lyme disease, however, it can react to antibodies to other diseases and conditions. That is why if this test is positive, a second test must be done to determine if the antibodies are due to Lyme disease. Both of these tests must be positive to be considered a Lyme case. The first test is usually called an ELISA test and the second test is usually called a Western Blot.

Antibodies are created by your immune system in response to an infection. Since it can take some time for your body to produce antibodies to an infection, it is possible that early Lyme testing will be negative even if you have the disease. If your Lyme test is negative but your symptoms persist, a second Lyme test might be ordered.

How does Lyme disease spread?

Lyme disease is spread through the bite of an Ixodes scapularis tick (also known as a deer tick or black legged tick). Deer ticks are found in every county of Pennsylvania, even in green spaces in urban areas. There is no evidence Lyme disease can be sexually transmitted or spread through household contact. Pregnant women should seek treatment for Lyme disease as soon as possible as Lyme disease can cause stillbirth if left untreated. There is no evidence Lyme disease can be transmitted through breastfeeding.

Is there is treatment or vaccine for Lyme disease?

Lyme disease can be treated with antibiotics. The antibiotic your healthcare provider prescribes will depend on your disease symptoms and other considerations like antibiotic allergies. Antibiotics are typically prescribed for 10, 14 or 28 days. Multi-month prescriptions of antibiotics are not recommended and have not been shown to be effective. This may also increase the risk of Clostridium difficile which is a diarrheal infection.

There is currently no human vaccine for Lyme disease.

Most people treated with antibiotics, especially those treated early, fully recover from Lyme diseases. About 20% of people may develop Post Treatment Lyme Disease Syndrome (PTLDS) which is a persistence of some Lyme symptoms even after antibiotic treatment. Most symptoms resolve within months. Repeated treatments with antibiotics have not been shown to be effective in treating PTLDS.

How can I protect myself from Lyme disease?

It is important to use insect repellent when you will be spending time outdoors. Wear protective clothing that is light in color and protects most of your skin. You may also treat your clothing and gear with permethrin. Once you come inside, take a shower and conduct a tick check. Read more about prevention.

How many cases of Lyme disease are there in Pennsylvania?

Lyme disease is one of the most common reportable infectious diseases in Pennsylvania. In 2017, 11,900 Lyme disease cases were reported in Pennsylvania; in 2018, that number dropped slightly to 10,208 cases. Although these are the reported cases, it is likely that the number of actual cases is much higher. CDC estimates that number of Lyme cases is about ten times the reported number. This means that Pennsylvania may have around 100,000 cases a year. That is about 1 case for every 100 people in Pennsylvania every year. See the Pennsylvania Lyme and Other Tickborne Diseases Surveillance Report 2017 for more data and analysis of Lyme disease.

Can my pets get Lyme disease?

Yes, our dogs, cats, and farm animals can get Lyme disease. Discuss the best tick and Lyme prevention products with your veterinarian. Dogs may be vaccinated for Lyme disease.

What should I do if I think I have Lyme disease?

Contact your health care provider if you developed symptoms of Lyme disease. Your health care provider may test your blood for Lyme disease and other tickborne illnesses.

More Information

  • Lyme Disease Fact Sheet (PDF)