Babesiosis; Human granulocytic anaplasmosis (HGA)
Many other illnesses can mimic various features of Lyme disease. Depending on the symptoms, a doctor may be able to perform the evaluations necessary to rule out other conditions.
Other infections can produce fever, headache, muscle aches, fatigue, and some of the neurologic or cardiac features of early Lyme disease. Some are transmitted by the same tick as Lyme disease.
Co-Infections Transmitted by the Ixodes Tick. Babesiosis and human granulocytic anaplasmosis (HGA) are transmitted by the same tick that carries Lyme disease. People may be co-infected with one or more of these infections, all of which can cause flu-like symptoms. If these symptoms persist and there is no rash, it is less likely that Lyme disease is present. Still, diagnosing a co-infection is difficult.
Other Spirochete Infections. Leptospirosis is a spirochete infection spread through animals or contaminated water that most often affects young people during the summer or fall.
Other Tick-Borne Infections. A number of other tick-borne diseases may resemble Lyme disease, although they are more common in parts of the U.S. where Lyme disease is less prevalent.
Allergic Reaction to the Tick. If a rash, even ring-shaped, appears hours rather than days after a tick bite, it is most likely an allergic reaction to the tick, not a symptom of Lyme disease.
Other Insect Bites. Not every rash seen in regions where Lyme disease is common is caused by a tick. The bites of many insects and spiders can cause a skin reaction.
A number of autoimmune diseases have chronic and low-level symptoms that may be confused with Lyme disease.
A number of conditions cause chronic fatigue and joint and muscle aches that resemble descriptions of post-Lyme disease syndrome:
The early neurologic symptoms of Lyme disease (headache, stiff neck, and fatigue) can easily be mistaken for viral meningitis. Children with viral meningitis are more likely to have a higher fever. Patients with Lyme disease often have other symptoms, such as the bull's-eye rash.
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