'Bull's Eye' Rash Not Always First Sign of Lyme Disease
(HealthDay News) – While many people who get Lyme disease have a rash from a tick bite as an early sign they've become infected, the singular "bull's eye" target isn't always there.
Actually, the rash starts out completely red most of the time, according to a study in the Annals of Internal Medicine . It found that fewer than one in 10 cases had a rash with a clearing in the middle.
But the researchers, who were looking specifically for Lyme, determined that many more rashes would have eventually turned into that classic shape.
"Although there is a characteristic pattern, circular or oval, there can be a fair amount of variety in their appearance," says one of the study's authors, Dr. Robert Smith, an infectious disease specialist at the Maine Medical Center Research Institute in Portland .
Every year more than 20,000 Americans are diagnosed with Lyme disease, according to the U.S. Centers for Disease Control and Prevention. It's transmitted through a bite from an infected tick, most commonly the deer tick. The infection is most prevalent in the Northeast, Mid-Atlantic and North Central regions of the United States .
Antibiotics are usually effective against Lyme disease. If left untreated, however, the infection can cause arthritis and neurological disorders. Symptoms can often be mistaken for other ailments, according to the American Lyme Disease Foundation. These include an expanding red rash, fatigue, fever, chills and joint pain.
"Rashes don't necessarily have to have a central clearing or a target-like appearance," says Dr. Gary Wormser, chief of the division of infectious disease at New York Medical College in Valhalla and author of an editorial that accompanies the study. "The majority of the time they don't have that appearance [in the early stages], and it's a common misconception."
For this study, Smith and his colleagues studied data from almost 11,000 participants in a Lyme disease vaccine trial. The participants were given information about Lyme disease, and were told to promptly report any possible symptoms of the disease.
During that trial, 118 of the volunteers were diagnosed with Lyme disease.
Only 9 percent of them had bulls-eye rashes. Fifty-nine percent had rashes that were red throughout, and 32 percent had rashes that were completely red, but somewhat darker in the center. About half of those infected had other symptoms, such as fever or fatigue.
Because the study participants were educated about Lyme and were looking for symptoms, the disease was recognized early in most cases. Both Smith and Wormser say it's likely many of the rashes that started out completely red would have eventually changed into a bulls-eye rash if left untreated.
Some of the participants who contracted Lyme had received the vaccine, which is not 100 percent effective, but the researchers found no significant differences in the rashes between the vaccinated group and the unvaccinated group.
The accompanying editorial suggests treatment for Lyme disease needs to be more standardized. For most early infections, Wormser says 14 to 21 days of antibiotics is enough to kill the infection. However, some doctors still prescribe 30 days or more of treatment.
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The American Lyme Disease Foundation recommends using insect repellant, wearing light-colored clothing and checking for ticks frequently. Adult deer ticks are about the size of a sesame seed, and the nymphs are only as big as a poppy seed.
For more information on Lyme disease, read this online section from the U.S. Centers for Disease Control and Prevention.
SOURCES:
Robert Smith, M.D., Director, Infectious Disease Fellowship, Maine Medical Center Research Institute, Portland; Gary Wormser, M.D., chief, division of infectious diseases, and professor, medicine and pharmacology, New York Medical College, Valhalla; March 19, 2002, Annals of Internal Medicine
Author:
Serena Gordon, HealthDay Reporter
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