Sir.—Dr Kunnamo and colleagues1 wrote a thorough description of the useful signs and tests in the differential diagnosis of childhood arthritis. However, they failed to mention the possibility of Lyme disease as a cause of childhood arthritis. We write to remind the readers of AJDC that in the United States, Lyme disease is becoming an increasingly common cause of juvenile arthritis.
First identified in coastal Connecticut, Lyme disease is now known to occur in large areas along the Atlantic
Coast, in Great Lakes states, and on the Pacific Coast. Foci in the Southeast and Midwest are now being identified. The disease appears to follow the geographical distribution of the voracious Ixodes tick, which transmits the Lyme spirochete to its host.
The characteristic rash associated with Lyme disease, erythema chronicum migrans (ECM), has been reported throughout much of Europe, including Finland. Schmid's2 global review of Lyme disease described the prevalence