Lyme disease is an infection caused by Borrelia burgdorferi, a bacteria transmitted to humans through bites from black-legged ticks, most commonly deer ticks. According to the American Lyme Disease Foundation, with more than 150,000 reported cases since 1982, Lyme disease is the most common arthropod-borne (the animal group ticks belong to) illness. Lyme disease is an inflammatory disease that affects many systems in the body. Because of this, the symptoms and their severity may vary from patient to patient, which can make accurate diagnosis difficult.
Rash
The most common symptom, occurring in 70 to 80 percent of those infected with Lyme disease, according to the Mayo Clinic, and often the first symptom to appear is a rash. The rash typically develops at the site of a tick bite and begins 3 to 30 days following a bite, reports the Centers for Disease Control and Prevention (CDC). The rash expands during the few days following the initial appearance, reaching up to approximately 12 inches across. During this expansion, the center fades, giving the rash a bull's-eye appearance. This type of rash is known as an expanding rash or, in medical terms, erythema migrans (EM).
The rash may be warm to the touch but is usually not painful. It may spread beyond the initial site of infection, creating lesions in other areas of the body.
Flu-Like Symptoms
The appearance of the rash is often accompanied by flu-like symptoms. These include a fever, chills, fatigue, headache and muscle aches.
Joint Pain
If left untreated, the bacterial infection spreads through the body and can produce arthritis-like symptoms. The CDC reports that approximately 60 percent of untreated patients have periodic episodes of arthritis characterized by severe joint pain and swelling. The larger joints are most commonly affected, such as the knees. The joint pain caused by Lyme disease is migratory, meaning it can shift from one joint to another.
Neurological
Lyme disease can also affect the central nervous system, which includes the brain, spinal cord and peripheral nervous system. Symptoms of peripheral nervous system infection include numbness and tingling of the hands and feet, and the sensation of shooting pains in the arms and legs.
Nerve damage caused by Lyme disease can result in a loss of muscle tone on one or both sides of the face. This condition is known as Bell's palsy.
The bacteria can also cause inflammation of the membrane surrounding the brain and spinal cord, called meninges, resulting in meningitis. Symptoms of meningitis include a stiff neck and severe headache. As the infection continues, it can result in cognitive damage, including memory loss, difficulty concentrating, mood changes and sleep disturbances.
