Julie-Ann M. Crewalk, MD
Pediatric Infectious Disease Group
Inova Fairfax Hospital for Children
We are often asked to evaluate patients with fatigue and body aches attributed to Lyme disease, without the clinical criteria to support this diagnosis. As we head into prime tick season, here are some pertinent points surrounding this infection.
The vector in our area is the deer tick, which is most active from April to October. Following a bite, there is an incubation period of anywhere from 3 to 32 days, after which an erythema migrans (EM) rash – the typical bull’s-eye lesion – may appear at the bite site. Within weeks to months, innate and adaptive immune responses seem to control disseminated infections; in some cases even without antibiotic therapy.
Early infection may be localized with an EM rash described as painless, burning or pruritic. Later symptoms range from multiple EM lesions and palsies of the cranial nerves (VII) to headaches, fatigue, fever, lymphadenopathy, nuchal rigidity and musculoskeletal pain. If left untreated, meningitis, encephalitis, and motor and sensory radiculoneuritis may occur. Though rare in children, carditis manifesting as a form of heart block can also emerge. Late infection often manifests as intermittent arthritis in the large joints, most commonly the knee. A few patients continue to have persistent arthritis despite oral therapy, and may require a second course of antibiotics.
Lyme disease diagnosis depends on the stage of infection. Early, localized disease is diagnosed clinically. Serologic testing is not recommended because it is often too early for antibodies to develop. Later stages can be diagnosed serologically in a two-step approach: if an enzyme-linked immunosorbent assay (ELISA) is equivocal or positive, follow up with a Western Blot test to confirm the result.
On a Western Blot assay, a band forms when antibody from the patient precipitates with antigen from the test solution. The more bands that form, the more likely the patient is to have Lyme disease. The IgM Western Blot is considered positive if at least two of the three bands are reactive. The IgG Western Blot is considered positive if at least five of 10 bands are reactive. After four to eight weeks, patients with Lyme disease will have a positive IgG Western Blot. Patients with symptoms beyond two months who have only a positive IgM are most likely false positives. Even after adequate treatment, antibody titers may be present for months to years, so using repeat serology as a marker for improvement or “test of cure” is not suggested.
I recommend the Red Book® for treatment options. The most common mistake we see is amoxicillin dosing: the daily amount should be divided into three doses. For children older than eight, doxycycline is the drug of choice because it can also treat Anaplasma phagocytophilum – a potential concomitant infection transmitted by the same deer tick.
All too often we see children who have been placed on months of inappropriate antibiotics and supplements for an incorrect diagnosis of Lyme disease. This limits our ability to find a true source for their symptoms, contributes to antibiotic resistance and causes potentially dangerous medical complications. Months of vague symptoms such as arthralgias, muscle pains and fatigue in patients with negative lab results for Lyme disease argue strongly against the diagnosis. Some of these patients require an in-depth workup for other etiologies. But most only require repeated reassurance.
Return to Pediatric Post entry page