What Does the Usual Lyme Disease Rash Look Like?
The characteristic Lyme disease rash does not always take the form of a bull’s eye. It may present in many different forms and patterns, or it may be missing completely.
The bulls eye rash, called erythema migrans, is that rash that is commonly associated with infection by Borrelia spirochetes subsequent to a tick bite. The Centers for Disease Control (CDC) and the Infectious Diseases Society of America (IDSA) consider this rash to be the most important symptom in the diagnosis and subsequent reporting of Lyme disease cases.
Detailed Description of the Rash
The stereotypical manifestation of erythema migrans is circular or elliptical rash which gets bigger during the span of several days and displays a prominent inner clear portion encircling a reddened middle. This is what gives the rash its common name: Bull’s eye. However, only about half of all Lyme disease patients present with this rash. In the remaining portion, it is either nonexistent or takes on an uncharacteristic appearance. The Lyme disease rash may be deep red with an irritated or elevated center or dark blue and red, strongly resembling a nasty bruise. Some people may even have rashes of varying shapes and sizes, making diagnosis difficult.
Roughly 10 percent of Lyme disease rashes, according to the Canadian Lyme Disease Association or CanLyme, are not of the stereotypical bull’s eye pattern. If someone exhibits a rash that is out of the ordinary, a doctor may not attribute it to having been bitten by a tick, therefore ruling out Lyme disease since it does not fit the usual pattern. An EM rash is normally 2 to 5 inches in diameter, but may be as small as a quarter or large enough to cover an entire leg or torso. A person can have many rashes at the same time.
Histology and Molecular Analysis of Erythema Rashes
According to the American Academy of Dermatology in March 2008, Dr. Carmen Moreno and her associates at Universidad Autnoma in Madrid, Spain, reported that Erythema migrans rashes had a comparable microscopic structure. There were higher levels of histocytes, or bacteria-eating immune cells, in the innermost layers of the skin. Also, the histocytes formed bunches by gathering in diffuse patterns bordered by thick bundles of collagen. The polymerase chain reaction biopsies from the far edges of the rashes of 11 patients invariably presented DNA from Borrelia than biopsies from the center portions. ELISA tests were only positive in samples taken from 5 of the patients, and IgM and IgG tests of the remaining 6 were either inconclusive or negative. According to CanLyme, as many as 70 percent of patients have negative ELISA results.
The CDC’s second method of supervision is a positive ELISA response. If a patient does not present a Lyme disease rash and proved negative on the ELISA test, then said patient cannot be diagnosed with Lyme disease, despite the results of any other tests.
What if There is No Rash?
Usually, when a person visits the doctor for suspected Lyme disease, the first questions the doctor asks are whether the patient saw a tick, and if there was a Lyme disease rash rash. Author of “Lyme Disease Update: Science, Policy and Law” says that 20% to 50% of people don’t see a Lyme disease rash and many don’t notice ticks. When patients answer “no” to the above questions, most doctors disregard Lyme disease as a possibility because of the lack of a rash.
EM is Typical to Lyme Disease
The CDC considers EM to be tantamount to Lyme disease. However, the interpretation of what EM is or isn’t is inconsistent and subjective. If EM presents in the stereotypical manner, doctors feel certain. Though if it is absent or unusual, they may refuse to diagnose Lyme disease. Most of this seems to be because the CDC and IDSA require or suggest a different diagnosis if a Lyme disease rash or ELISA test are negative, despite any clinical presentations.