Erythema migrans

Erythema migrans is an early manifestation of Lyme disease and the most common skin lesion associated with it.

The principle vector of this is the Ixodes tick which causes a Borrelia burgdorferi infection, usually picked up in woodland/ forest areas

It begins as a small macule or papule at the site of the bite. It enlarges slowly over days and begins to take shape as a well demarcated circular or ovoid lesion.  It is uniformly red to begin with however can later clear at the centre around the site of the initial tick bite giving an annular appearance.

It usually presents with pain, burning and pruritus.

Diagnosis is usually clinical but can be confirmed using serology for Borrelia burgdorferi infection, although results may be negative in the first few weeks of infection and may remain positive years following successful treatment.

Management includes preventative measures such as wearing white clothes when in endemic areas so that the tick could be more easily visualised, wearing long sleeves and long trousers as well as thorough checking of your whole body when returning from higher risk areas

Treatment of potential Borrelia Burgdorferi infection should be commenced without delay on presence of erythema migrans or other clinical indicators, this is done using a prolonged course of antibiotic therapy (14-21 days of Doxycycline or amoxicillin)

References

http://www.pcds.org.uk/clinical-guidance/lyme-disease