Rashes and Symptoms in Early Lyme Disease

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The summary below is from the full report titled "Clinical Characteristics and Treatment Outcome of Early Lyme Disease in Patients with Microbiologically Confirmed Erythema Migrans." It is in the 19 March 2002 issue of Annals of Internal Medicine (volume 136, pages 421-428). The authors are RP Smith, RT Schoen, DW Rahn, VK Sikand, J Nowakowski, DL Parenti, MS Holman, DH Persing, and AC Steere. The summaries may be reproduced for not-for-profit educational purposes only. Any other uses must be approved by the American College of Physicians–American Society of Internal Medicine.

What is the problem and what is known about it so far?

Lyme disease is a bacterial infection that is transmitted to humans by ticks that usually live on mice or deer. Most infections are acquired in three distinct sections of the United States, particularly along the northeast coast, in areas of Wisconsin and Minnesota, and to a lesser extent in northern California. People who hike, camp, or live in or near wooded areas in these locations during summer months are most at risk for Lyme disease. If a deer tick bites them, they may get a red bump at the site of the bite. If the tick is infected, a larger area of redness may form around the bite days later and expand slowly. Symptoms such as chills, fever, fatigue, headache, and joint pains may accompany the rash. The classic description of the rash is an enlarging area of redness with partial central clearing. However, it may take a number of days before the lesion expands enough to have the classic appearance.

Why did the researchers do this particular study?

To describe the early signs and symptoms of Lyme disease.

Who was studied?

118 adults with Lyme disease who lived in 10 states in which Lyme disease frequently occurs.

How was the study done?

The researchers followed almost 11,000 people in a study that was designed to test a Lyme disease vaccine. All participants were told about Lyme disease and its symptoms. They were asked to report promptly to the researchers if they noticed any symptoms of Lyme disease. During 20 months of follow-up, 1917 people reported suggestive symptoms. Of these, 118 had Lyme disease documented by detection of the bacteria in skin biopsy samples of the rash.

What did the researchers find?

All of the 118 patients presented with a red skin rash. The rash usually had the same color throughout (59%) or was redder in the center (32%). Only 9% of the rashes had a clear area in the middle (classic erythema migrans). Half of the rashes were on the lower part of the body (groin, hips, legs), while one quarter were on the shoulder, armpit, or upper arm. Although 30% of the people reported fever, an elevated temperature was noted on examination in only 6%. About one third reported flu-like symptoms, such as muscle and joint pains and headache; 43% reported no symptoms. Rashes and symptoms usually went away with antibiotic treatment. However, 13 patients still had symptoms 30 days after starting treatment.

What were the limitations of the study?

This study describes people with early Lyme disease during the first days of symptoms. Patients who have had Lyme disease for several days or weeks may have different signs and symptoms.

What are the implications of the study?

Most patients with Lyme disease have a rash. During the first few days of Lyme disease, the rash is usually solid red and has not enlarged enough to have partial central clearing.