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Lyme Disease Rash

Lyme Disease Rash

Bull's Eye rash in darker skinned people often goes unnoticed

The characteristic bull’s eye Lyme disease rash is referred to as erythema migrans and is a common early sign of infection with Borrelia bacteria.  The circular rash represents the gradual spread of infectious spirochaetes through the skin prior to the bacteria entering the bloodstream and disseminated Lyme disease occurring.  Not all cases of Lyme disease are indicated by such a rash however, with fever, chills, and other flu-like symptoms common in early infection.  In some cases a person may develop a rash at a site far away from the initial tick bite and/or a recurrence of the early Lyme disease rash several weeks or even months after being bitten.

Erythema migrans is usually characterized as a central indurated red spot surrounded by a red ring, sometimes with an inner ring of normal colored skin between the two.  The hardened centre is usually darker than the outer ring, but not always, and the general area of the rash may be warm to the touch.  In some cases the rash may be itchy although a particular protein in ticks’ saliva has the common effect of reducing pain and itchiness at the bite site, as well as facilitating transmission of bacteria into the host’s body.

People with darker, or tanned skin may not notice the Lyme disease rash, especially where it is not painful or itchy.  Ticks are also apt to choose bite sites which are difficult to see, such as the armpits, the back of knee, or in the groin.  A Lyme disease rash in dogs can be particularly difficult to see as it is often covered by their fur.  Similarly, ticks can bite a person on their head or scalp and remain hidden in the hair whilst feeding.  Checking your skin with a magnifying glass following exposure to the outdoors in areas where ticks are endemic can help reduce Lyme disease transmission by removing a tick before it actually bites or at least before it has had sufficient time to spread infection with Lyme disease bacteria.

Seeking Medical Attention for Bull’s Eye Rash

The characteristic Lyme disease rash is not necessary for a diagnosis to be made but may help decide whether a Lyme disease test is warranted in the presence of other symptoms such as fever, malaise, unexplained joint aches and pains, or even neurological symptoms.  Where erythema migrans develops it is important to seek medical attention quickly as prompt antibiotic treatment has a high rate of success for eradicating infection before any long-term damage occurs.  Antibiotic treatment in late-stage Lyme disease can still be successful but does become more complicated.

History and Incidence of the Lyme Disease Rash

Erythema migrans is such a common, and distinctive sign of Lyme disease in North America that it is the only such manifestation of the condition that allows clinical diagnosis without confirmation from a laboratory blood test for Lyme disease.  Although the rash may have disappeared by the time medical attention is sought for subsequent symptoms such as arthritis development or cognitive deficits, where Lyme disease is suspected a physician may retrospectively diagnose erythema migrans from a patient’s description of such a rash.  No other pathogen causes a similar rash, however the term erythema migrans is sometimes applied to a condition called geographic tongue with the name erythema chronica migrans more appropriately delineating the Lyme disease rash itself.

Arvid Afzelius

Scientist Arvid Afzelius

Who discovered Bull’s Eye Rash Lyme Disease Association?

The scientist Arvid Afzelius is credited with making the association between erythema chronica migrans, tick bite, and Lyme disease in the early 1900s.  Afzelius described the ring-like skin lesion and attributed it to bite by the Ixodes tick.  Earlier instances of the rash have been documented, dating back to the 1800s, but it was Afzelius who connected the symptom with Lyme disease.  Confusion may occur between a ringworm infection and erythema chronica migrans as the central red spot may be faint in some cases of the Lyme disease rash, leaving just an outer red ring.   The rash is thought to occur in around 70-90% of cases of Lyme disease infection, although some patients, such as women, and those in Europe, rather than North America, are more likely to develop this symptom.  This is due to a high rate of erythema migrans occurring with Borrelia afzelii in contrast to Borrelia burgdorferi sensu stricto.  Those infected with B. garinii may instead develop a non-annular (no central clearing) red blotch.

Early disseminated Lyme disease is often indicated by the presence of the bull’s eye rash in two or more locations on the body away from the actual site of the tick bite.  Lyme disease symptoms include erythema migrans which may occur within 3-30 days following infection with Borrelia bacteria, with an average development time of 1-2weeks after transmission.  The habit of ticks biting in skin folds or hard-to-see places means that a patient may not notice the bite initially and may only be alerted to it by a partner or friend.  The rash may be located to a small area with the average diameter around 5-6 inches.  Some instances of the Lyme disease rash may cover the whole of a patient’s back however, and multiple bites can cause a crossover of the annular skin lesions.  A common feature of the rash is its expansion over a period of days as the infectious spirochaetes spread through the skin.

How Long does Bull’s Eye Rash Last?

The characteristic Lyme disease rash or Bull’s Eye Rash usually lasts for around 3-5 weeks but can also be as brief as a single day before dissipating.  This can make it difficult to notice for some patients, and symptoms such as joint aches and tiredness may simply be attributed to a strenuous hike meaning that Lyme disease has an opportunity to disseminate before being diagnosed and treated.  Such symptoms of Lyme disease, including headaches, fever, chills, and lethargy, can re-occur weeks, months, or even years after the initial bite where the infection remains untreated or resistant to treatment with antibiotics.  Although the existence of chronic Lyme disease without signs of current infection remains under debate, symptoms of the disease may be misdiagnosed as part of chronic fatigue syndrome, fibromyalgia, or even acute psychosis in some cases.  It is especially important then for a doctor to question a patient about the nature of any recent rashes which may resemble erythema migrans, prior to chronic symptoms developing, as a Lyme disease rash offers a clear pathognomonic sign.