3 Conditions That May Be Mistaken for Lyme Disease

Lyme disease ring on body
Lyme disease ring on body
Lyme disease is difficult to diagnose accurately. We explore 3 conditions clinicians might mistake for the tick-borne illness.

Lyme disease is difficult to diagnose accurately. Not all patients present with its signature symptom, erythema migrans (EM), with or without the presence of a bull’s-eye-shaped rash. Other symptoms such as fever, chills, fatigue, and headache are nonspecific. The people who are infected with the tick-borne illness don’t always remember being bitten by a tick. And, to compound matters, testing for Lyme disease is not an exact science.

As a result, sometimes people who are infected with Lyme disease are incorrectly diagnosed with other ailments such as fibromyalgia, rheumatoid arthritis, and multiple sclerosis (MS). These chronic conditions aren’t the only illnesses that can be mistaken for Lyme disease. We explore 3 Lyme-like conditions that might not immediately come to mind.

Borrelia miyamotoi Disease

Borrelia miyamotoi (B miyamotoi) disease is an emerging infectious disease spread by deer ticks. First discovered by Japanese scientists in 1995, B miyamotoi disease can be found in all areas of the United States where Lyme disease is endemic.1

The first human cases of B miyamotoi infection were found in Russia in 2011, when researchers identified 46 patients who had presented with the influenza-like illness.2 Two years later, the first recognized cases in North America were reported in the Northeastern United States.3

Symptoms of B miyamotoi infection are similar to those seen in Lyme disease: fever, chills, headache, joint pain, muscle pain, and fatigue. One key difference: patients with B miyamotoi disease rarely develop a rash. Whereas just 4 (9%) of the 46 cases of B miyamotoi infection identified in Russia involved EM, an estimated 70% to 80% of people with Lyme develop a rash.4

Blood tests to identify Lyme disease are not effective in diagnosing B miyamotoi disease. Instead, polymerase chain reaction (PCR) that detect B miyamotoi DNA and antibody-based tests are used to confirm a diagnosis.  Doxycycline, amoxicillin, and ceftriaxone have been used successfully to treat patients with B miyamotoi infection.5

Summer Flu

Early symptoms of Lyme disease such as fever, chills, fatigue, and pain closely resemble those of influenza. Because Lyme disease is not always accompanied by a rash, the tick-borne illness can be mistaken for the summer flu. One such case was documented in Orthopedic Reviews.6

A 58-year-old woman presented with flu-like symptoms including body aches, headache, and fever. She was diagnosed with acute influenza and prescribed antiviral medication. Two days later, she reported a welt on her stomach and generalized joint pain. She revealed that 3 weeks prior she had irritation or a bite behind her knee that she couldn’t see. Examination revealed an EM lesion behind her knee, and the patient was administered doxycycline. Her symptoms resolved in the following week.

“This case report illustrates the difficulty in distinguishing patients with early Lyme disease from those with an undifferentiated viral illness,” the authors wrote. “The viral-like symptoms of fever, headache, stiff neck, body aches, and fatigue are the common presenting features of many infections, both viral and non-viral. These illnesses often lack localizing symptoms such as cough, diarrhea, or urinary symptoms that point to more specific diagnosis such as pneumonia, gastroenteritis, or genitourinary infection.”

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Patients with cellulitis typically present with warmth, tenderness, inflammation, swelling, redness, and/or pain in the affected area. As such, the bacterial infection can be mistaken for Lyme disease.

A study in the Archives of Family Medicine identified several patients who were originally diagnosed with cellulitis but actually had Lyme disease. The researchers noted that, despite its distinctive appearance, EM may be confused with the bacterial infection. 7

A case study in Clinical Infectious Diseases chronicled a 39-year-old man who suddenly lost consciousness and collapsed. After the patient was revived in the emergency department (ED), he reported that he had consulted a clinician 3 weeks earlier for a rash that was subsequently diagnosed as cellulitis. However, following cardiology consultation in the ED, an ELISA test for Lyme disease was conducted; the study was reported as positive and confirmed by Western blot.8

The author argued that the case history “illustrates failure of patients to be aware of tick bites and failure of diagnosis by a primary physician even in an area of endemicity.”


  1. Glatter R. The disease that looks like Lyme – but isn’t. Forbes. July 12, 2013. Accessed May 28, 2019.
  2. Platonov AE, Karan LS, Kolyasnikova NM, et al. Humans infected with relapsing fever spirochete Borrelia miyamotoi, Russia. Emerg Infect Dis. 2011;17(10):1816-1823.
  3. Molloy PJ, Telford SR 3rd, Chowdri HR, et al. Borrelia miyamotoi disease in the northeastern United States: a case series. Ann Intern Med. 2015;163(2):91-98.
  4. Signs and symptoms of untreated Lyme disease. Centers for Disease Control and Prevention. Reviewed December 21, 2018. Accessed May 28, 2019.
  5. B. miyamotoi. Centers for Disease Control and Prevention. Reviewed January 10, 2019. Accessed May 28, 2019.
  6. Aucott JN, Seifter A. Misdiagnosis of early Lyme disease as the summer flu. Orthop Rev. 2011;3(2):e14.
  7. Nowakowski J, McKenna D, Nadelman RB, et al. Failure of treatment with cephalexin for Lyme disease. Arch Fam Med. 2000;9(6):563-567.
  8. Plotkin SA. Correcting a public health fiasco: the need for a new vaccine against Lyme disease. Clin Infect Dis. 2011;52 Suppl 3:s271-s275.