Knee Swelling Years After a Tick Bite: Lyme Arthritis in a Child
Joint swelling appeared years after exposure
No early Lyme symptoms were reported
Diagnosis depended on history and targeted testing
In their article, “Ten-year-old Omani Girl with Lyme Arthritis,” Mughaizwi and colleagues describe a delayed presentation of Lyme disease in a child.
A 10-year-old girl developed acute swelling of her left knee one year after returning to Oman, following several years living in upstate New York—an area endemic for Lyme disease. :contentReference[oaicite:0]{index=0}
Symptoms Appeared Years After Tick Exposure
The child recalled two tick bites that occurred 2–3 years before symptom onset.
She presented with:
- Marked swelling of the left knee
- Mild tenderness and warmth
- Reduced joint mobility
She had no prior rash, neurologic symptoms, or joint complaints—features often associated with early Lyme disease.
Initially Treated as Septic Arthritis
MRI revealed a large joint effusion with synovial thickening, raising concern for septic arthritis.
The patient underwent joint aspiration, which improved mobility.
However, her history of prior tick exposure prompted further evaluation.
Lyme Arthritis Confirmed
Laboratory testing revealed:
- Positive ELISA for Lyme disease
- PCR detection of Borrelia burgdorferi in joint fluid
This confirmed Lyme arthritis, a late manifestation of infection.
These patterns are part of the broader spectrum described in our Lyme disease symptoms guide.
Successful Treatment and Recovery
The patient was treated with a 4-week course of intravenous cefuroxime.
She made a complete recovery.
Key Clinical Lessons
- Stages can overlap: Late disease may appear without clear early symptoms
- Symptoms may be delayed: Onset can occur months or years after exposure
- Exposure history matters: Prior residence in endemic regions is a critical clue
These diagnostic challenges are discussed further in our delayed Lyme disease diagnosis guide.
Lyme Arthritis vs Septic Arthritis
Lyme arthritis can resemble septic arthritis, particularly with acute joint swelling.
However, Lyme arthritis often:
- Develops over days rather than hours
- Lacks high fever or systemic toxicity
- Occurs in patients with prior tick exposure
Understanding this distinction is critical for appropriate management. See more in our Lyme arthritis in children guide.
Why This Case Matters
This case highlights how Lyme disease can remain unrecognized for years before presenting as arthritis.
When children present with unexplained joint swelling—especially with a history of travel or tick exposure—Lyme disease should remain part of the differential diagnosis.
Start here: Lyme disease symptoms guide
Related Articles:
Diagnosing Lyme arthritis of the hip in children
Reference:
- Mughaizwi T, et al. Lyme arthritis in a child. Oman Med J. 2022. View study
Dr. Daniel Cameron, MD, MPH
Lyme disease clinician with over 30 years of experience and past president of ILADS.
Symptoms • Testing • Coinfections • Recovery • Pediatric • Prevention
I had these symptoms back in early 70s here in Canada. I was diagnosed with Juvenile Arthritis and nothing was done, not even aspirating or antibiotics. Additionally, I had severe leg and hip pain plus other symptoms. Lyme disease was not even a thing recognized here in the 70s. I was not diagnosed with this until 2017, because I advocated for myself. Thanks to advocacy groups, ILADs, LLMDs, researchers, the internet and social media for putting this out there, so we have a fighting chance. Parents and children today hopefully have a better chance at recovery, because of the aforementioned resources.
Your story is all too common.