Lyme disease is an inflammatory disease that can impact the joints, heart and nervous system. Symptoms include rash, fever, headaches and joint pain. Lyme disease is caused by a species of bacteria that's most often spread to humans through tick bites.
Chronic Lyme disease is a controversial diagnosis -- not all doctors believe that it exists. Those who believe in it think that antibiotic treatment that usually cures Lyme may sometimes be ineffective, leading to an on-going infection that can cause persistent and possibly debilitating symptoms.
Some chronic fatigue syndrome doctors and researchers believe that chronic Lyme disease may play a role in causing and/or sustaining chronic fatigue syndrome. Research has thus far failed to confirm the connection.