Lyme disease rash may not look like a bulls-eye
Lyme disease is a bacterial infection transmitted to humans by ticks that usually live on mice or deer. Though various symptoms are associated with Lyme disease, the hallmark symptom has been a round red rash with clearing in the middle, resembling a bulls-eye. However, recent research published in the Annals of Internal Medicine suggests that the rash may not always have the characteristic clearing in the middle.
About the study
Researchers from medical centers in New England, New York, and Georgia analyzed data from the Lyme Disease Vaccine (LDV) Study—a 20-month study of the safety and effectiveness of the Lyme disease vaccine LYMErix. The study was sponsored by SmithKline Beecham—the company that manufactures LYMErix. In the LDV study 10,936 people were randomly assigned to receive either LYMERix or a placebo. They were also given written information about Lyme disease and told to contact their doctors if they experienced any symptoms suggestive of the disease.
One hundred eighteen participants in the LDV study were diagnosed with Lyme disease and treated with antibiotics for 14 to 30 days. Cases of Lyme disease were confirmed with blood tests and cultures of skin from the rash.
For this recent study, the researchers studied the medical records of the 118 participants with Lyme disease, specifically looking at:
- What symptoms were reported
- What type of rash was present
- When symptoms were reported
- How long antibiotic treatment lasted
- When symptoms resolved
Note: The LYMErix vaccine is no longer available in the United States. It was voluntarily removed from the U.S. market by the manufacturer in February 2002.
Surprisingly, only 9% of the study participants who had Lyme disease presented with the classic bulls-eye rash with clearing in the middle. Fifty-nine percent presented with a solid rash and 32% had more redness in the middle areas of the rash. Treatment with antibiotics for 14 to 30 days resolved the infection in the majority of cases.
The researchers also found that the longer people had symptoms, the more likely they were to test positive on blood tests for Lyme disease. Only 27% of people tested positive when they had symptoms for less than 7 days, compared with 41% for 7 to 14 days, and 88% for more than 14 days.
There are limitations to this study, however. Because the participants were specifically looking for symptoms of Lyme disease, they reported them immediately. Therefore, the cases in this study represent only very early stages of the disease. Most Lyme disease cases are reported to a physician later, when symptoms, such as the shape of the rash, may be different. In addition, antibiotic treatment ranged from 14 to 30 days, so it was not possible to determine an optimal length of antibiotic treatment.
How does this affect you?
Is the classic bulls-eye rash really a sign of Lyme disease? Yes, but the findings of this study suggest that, in its very early stages, a Lyme disease rash may have a more solid pattern rather than the classic bulls-eye. However, as the rash develops, it may take on the characteristic bulls-eye pattern.
If you suspect you may have Lyme disease, but your rash is solid, you should still consider having it checked out by your doctor. Other symptoms of Lyme disease that often accompany the rash include fever, headache, stiff neck, joint and muscle pain, and fatigue.
Finally, these findings also indicate that antibiotic medication is effective in treating early stage Lyme disease, but the precise length of treatment is uncertain. At this time, the Infectious Disease Society of America recommends 14 to 21 days of antibiotic medication (usually doxycycline or amoxicillin) for the treatment of Lyme disease.
Smith RF, et al. Clinical characteristics and treatment outcome of early Lyme disease in patients with microbiologically confirmed erythema migrans.
Annals of Internal Medicine . March 19, 2002;136(6):421-428.
Nadelman RB and Wormser GP. Recognition and treatment of erythema migrans: are we off target?
Annals of Internal Medicine
March 19, 2002;136(6):477-479.
Last reviewed Mar 22, 2002 by ]]>Richard Glickman-Simon, MD]]>
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