If a rash returns after you've been treated for Lyme disease, chances are it's a new infection, a new study suggests. Lyme is caused by bacteria that are transmitted by tick bites. Taking antibiotics cures most people. But for some the symptoms don't go away or return. The new study included 17 people who had been treated for Lyme disease. Then the distinctive "bull's eye" rash came back, in some cases up to 3 times. Skin or blood samples were taken after each rash appeared. They all showed Borrelia burgdorferi bacteria, the type that causes Lyme disease. In the new study, researchers looked more closely. They did a genetic analysis of the samples. In each case, the bacteria that caused the first outbreak and later outbreaks were different strains. That means there was a new infection, not a return of the old infection. The rash also appeared at a different spot when it returned. And the symptoms all occurred during prime tick season, spring or summer. Researchers concluded that people got infected again by new tick bites. The New England Journal of Medicine published the study. National Public Radio, HealthDay News and Reuters Health news service covered the story.

By Robert H. Shmerling, M.D.
Harvard Medical School

What Is the Doctor's Reaction?

Lyme disease has been shrouded in mystery ever since it was first reported in the early 1970s.

When a large number of children developed arthritis in Lyme, Conn., doctors there thought the cause was juvenile rheumatoid arthritis. But the cluster of cases occurred in certain wooded neighborhoods. This raised the possibility of an infectious disease as the cause.

In 1981, the true cause was uncovered -- a bacterium called Borrelia burgdorferi transmitted by tick bites. Thus the mystery was solved.

Yet more mysteries were to follow. Blood tests used for diagnosis weren't always reliable, especially just after the rash appeared. And, for some people with Lyme disease, the symptoms didn't go away. They continued to have a rash, joint pain or trouble concentrating despite proper treatment. This raised the notion of "chronic" or "resistant" Lyme disease caused by continued infection. Some thought this might require more antibiotics, lasting weeks or even months (and sometimes years!).

Even now, the very existence of chronic Lyme disease is controversial. Most doctors believe that symptoms after proper treatment of Lyme disease are not caused by active infection. Therefore, extra antibiotics won't help. But some doctors and patients disagree. They say that long-term courses of antibiotics, sometimes given intravenously (in a vein) may be required for lasting symptoms.

This new study weighs in on one aspect of the disease: the rash. When a rash returns after treatment, it could be because the antibiotics failed and the infection persists. Or could it be a new infection?

Through sophisticated testing, the researchers showed that the new symptoms were caused by a different strain of Borrelia. This means there was a new infection, not a return of the first infection. Therefore, retreatment was necessary.

This is important because it lends support to two features of Lyme disease:

• Even though people have antibodies to Borrelia burgdorferi after an initial bout of Lyme disease, they can get it again.
• Initial treatment of Lyme disease is usually effective.

Lyme disease remains a confusing condition. But research such as this can help. By clarifying whether symptoms are caused by relapse or reinfection, it can also guide better treatment.

What Changes Can I Make Now?

While aspects of Lyme disease remain controversial, there is little debate about how to prevent it. If you are in an area where Lyme disease is common, take steps to prevent tick bites. For example:

• Avoid tall grass, brush and woods. That's where ticks most commonly come into contact with people.
• Keep well covered. Wear long pants and long sleeves.
• Wear white. That will make it easier to spot ticks and remove them before they have a chance to bite.
• Check your skin each day, especially if you've been outside.
• Apply approved tick repellants to your clothing and skin.
• Get your dog vaccinated for Lyme disease. Unfortunately, a human vaccine is no longer available.

If you find a tick attached to your skin, remove it right away, but carefully. Contact your doctor to find out if you should take antibiotics to prevent Lyme disease. If the tick is swollen, it may have been attached for a while. In this case, preventive antibiotics are more likely to be recommended, especially if Lyme is common where you are.

Know the symptoms and signs of Lyme disease. Soon after the tick bite, symptoms include:

• Muscle and joint aches
• Fatigue
• Rash (called erythema migrans) -- Though it can take many forms, it's usually:
  
  • Large (more than 2 inches)
  • Red or pink
  • Flat

The rash spreads out from the tick bite. There may be a clear area of normal skin in the center. This is sometimes called a "bull's eye rash."

Days to months after the rash, other areas of the body may be affected. Common symptoms include:

• Nervous system -- headache, stiff neck, facial weakness
• Heart -- irregular heart rhythm, dizziness, fainting
• Joints -- swelling, pain and stiffness (usually in one knee)

If you have any of these symptoms -- and especially if they follow a tick bite -- contact your doctor right away. Fortunately, antibiotics lead to a prompt and complete recovery for most people with Lyme disease.

What Can I Expect Looking to the Future?

In the future, it seems likely we'll understand more about this mysterious illness. And that could lead to better prevention, tests and treatments. I hope that an effective vaccine for Lyme disease will soon become available again. Studies like this one lend support to the idea that antibiotics are usually effective and that a return of symptoms may not be caused by a failure of treatment. In the future, I hope that scientific study will resolve the controversy regarding "chronic Lyme disease."