An “Erythema Migrans” skin rash is more often incorrectly referred to as the “bull’s eye” rash. Current research has shown that only a small subset of the strains/species of bacteria that cause Lyme disease will cause a rash of any kind. Of the few that do cause a rash only 9% of those will take the over-emphasized ‘bull’s eye’ form. The vast majority will get no rash and those that do most rashes are more generalized in appearance.
[CanLyme note: Recent case reports in Nova Scotia showed that only 18 % of children with confirmed Lyme Disease had any rash.]
It is important to compare your rash with other known skin rashes that are not Lyme related. ie. ringworm (Tinea), a fungal infection that your physician should test for by scraping a little material off the rash area and having it tested for the fungus. Ringworm can be treated with anti-fungal creams.
Many doctors tell patients that what they have is a spider bite … the only spider bites that leave rashes that may be confused with Lyme disease will very quickly (within hours) become extremely painful, unlike a Lyme disease rash.
No evidence or recall of a rash does NOT mean no Lyme Disease to the clinician. If it one does occur it is not always a bull’s eye and can be generalized in appearance.
A Lyme disease rash is not always at the site of the tick bite. Many myths about the rash have resulted in misdiagnosis. One such myth is that the rash is usually the size of a quarter or silver dollar. The rash may vary greatly in both size and appearance. There may be more than one on the body (several at one time).
The most damaging myth is that all patients who have Lyme disease or at least the large majority get a rash of any kind. This has been proven to not be the case yet far too many physicians use this as the main diagnostic criteria rendering a negative diagnosis.