Positive IgM Immunoblot in Children With Lyme Disease
Researchers examined positive IgM immunoblots in children.
Some positive results were questioned as false positives.
Clinical judgment remains essential in pediatric Lyme disease.
Lantos and colleagues from Duke University Medical Center questioned the accuracy of the IgM immunoblot for Lyme disease in children and adolescents by reviewing patients admitted to Boston Children’s Hospital during a 7-year period.
The study, “False Positive Lyme Disease IgM Immunoblots in Children,” published in The Journal of Pediatrics, concluded that IgM immunoblots are valuable in the diagnosis of early Lyme disease in children.
Positive IgM Immunoblots in Early Lyme Disease
Lantos and colleagues reviewed 167 children admitted to Boston Children’s Hospital between January 1, 2007 and June 30, 2014.
Among these children:
- 71% (119 children) were determined to have Lyme disease
- 35% (58 children) had an erythema migrans (EM) rash
- 43% (71 children) had signs of early disseminated Lyme disease
Of the 71 children with early disseminated Lyme disease:
- 38 had radiculoneuropathy
- 28 had meningitis
- 5 had carditis
According to Lantos, these findings supported the usefulness of the IgM immunoblot in appropriately selected children with early Lyme disease.
When Is a Positive IgM Considered a False Positive?
Lantos and colleagues questioned the accuracy of IgM immunoblots in 48 children who did not meet established diagnostic criteria for Lyme disease.
According to the authors:
- 10 children had symptoms lasting more than 60 days
- 14 children had arthritis
- 24 children had nonspecific symptoms lasting longer than 60 days
The authors concluded:
“A positive IgM and a negative IgG in a child with a long duration of symptoms, late manifestations or nonspecific clinical presentation is likely a false positive result for Lyme disease.”
Persistent Symptoms in Children With Lyme Disease
Questions remain regarding how to interpret prolonged symptoms and nonspecific presentations in children evaluated for Lyme disease.
Steere and colleagues previously described outbreaks of oligoarticular arthritis in children and adults in Connecticut communities.
Patients experienced:
- Recurrent arthritis attacks
- Fatigue
- Headaches
- Myalgias
- Periods of remission between flares
Steere noted that some attacks lasted for months, while others recurred after symptom-free intervals.
Long-Term Neurocognitive Symptoms Reported in Children
Several studies have described persistent neurologic or neurocognitive symptoms in children following Lyme disease.
Bloom and colleagues from Tufts University School of Medicine reported that 5 of 86 children developed behavioral changes, forgetfulness, declining school performance, headaches, fatigue, or partial complex seizure disorders following Lyme disease.
Vázquez and colleagues from Yale University reported that children with prior cranial nerve palsy attributable to Lyme disease had significantly higher rates of:
- Behavioral changes
- Arthralgias and myalgias
- Memory problems
These symptoms persisted an average of four years after treatment.
To learn more, see Lyme test accuracy, types of Lyme disease tests, and pediatric Lyme disease.
Clinical Perspective
Positive IgM immunoblots can be difficult to interpret, particularly in children with prolonged or nonspecific symptoms.
Laboratory findings should always be interpreted alongside clinical history, symptom patterns, exposure risk, and physical examination findings.
The study by Lantos and colleagues highlights the importance of clinical judgment in children who do not develop a positive IgG immunoblot despite symptoms concerning for Lyme disease.
Related Articles:
References:
- Lantos PM, Lipsett SC, Nigrovic LE. False Positive Lyme Disease IgM Immunoblots in Children. J Pediatr. 2016.
- Steere AC, Malawista SE, Snydman DR, et al. Lyme arthritis: an epidemic of oligoarticular arthritis in children and adults in three Connecticut communities. Arthritis Rheum. 1977;20(1):7-17.
- Bloom BJ, Wyckoff PM, Meissner HC, Steere AC. Neurocognitive abnormalities in children after classic manifestations of Lyme disease. Pediatr Infect Dis J. 1998;17(3):189-196.
- Vazquez M, Sparrow SS, Shapiro ED. Long-term neuropsychologic and health outcomes of children with facial nerve palsy attributable to Lyme disease. Pediatrics. 2003;112(2):e93-97.
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
