Lyme disease is one of the most insidious illnesses around.
It gets you while you're doing something pleasant -- like walking in the woods on a summer day.
The tick that carries it is so tiny -- the size of the period at the end of this sentence -- that you can barely see it. And seeing it is important, because if you pick it off with tweezers within 24 to 48 hours, chances are you won't get sick.
Finally, the circular red rash that develops around the tick bite is easy to miss. Yet if you ignore it, or the fever, chills, headache and fatigue that will follow in the next few weeks, you may miss your best chance to stop the disease before it turns chronic -- and causes trouble for years.
Like chronic fatigue syndrome or fibromyalgia, Lyme disease, especially the chronic form, has been so misunderstood that frustrated patients and mystified doctors have long been at odds. But following a conference of doctors and activists last month at the National Institutes of Health, the hostilities seem to be simmering down and the scientific controversies coming into sharper focus.
Both activists and researchers agree that preventing Lyme disease is both possible and critical. They also agree that no one really knows how many people have it -- it's both vastly underdiagnosed and, in some cases, wrongly diagnosed in people who don't really have it.
The federal Centers for Disease Control and Prevention in Atlanta counted 16,197 new cases nationwide last year, up from roughly 12,000 the year before.
The tick that spreads Lyme disease -- and two other diseases called babesiosis and ehrlichiosis -- has a complex life cycle. In the larval stage, the tick lives on white-footed mice. The tick then molts, becomes a nymph, drops off the mouse and sits in low brush waiting for another animal to feed on.
It is at this stage that a tick bite is most infectious to humans. In its adult stage, the ticks live on deer. This means that large deer populations help keep the ticks' life cycle humming. Adult ticks can also infect humans, but less readily.
Treatment still in dispute
It's the diagnosis and treatment of Lyme disease that really gets complicated -- and controversial.
Once the telltale rash is gone, for instance, it is difficult even to diagnose Lyme disease. CDC's guidelines suggest using a lab test, called ELISA, to check for antibodies against the spirochete, the bacterium that lives in ticks. But this test can be inconclusive, so a second, more specific, antibody test called a Western blot is often done.
But even this may not be decisive. It can take weeks for the body to make antibodies, so a newly infected person may test negative but still have the disease. And some people seem to have Lyme disease without any detectable antibody response.
Some doctors also use another test, called PCR, or polymerase chain reaction, to look for pieces of DNA from the spirochete itself. But if, as some suspect, the spirochete can hide inside nerve and immune cells, this could make it harder to detect by PCR.
For some people who never noticed a bite or rash, the first sign of acute infection is meningitis, an inflammation of the lining of the brain, or a type of facial paralysis called Bell's palsy, or fainting due to heart block -- an electrical malfunction caused when the spirochete infects the heart.
Once acute Lyme disease is diagnosed, the usual remedy is 10 to 30 days of oral antibiotics -- usually doxycycline or amoxicillin, says Dr. Allen Steere, chief of rheumatology and immunology at the New England Medical Center, although a newer drug called Ceftin can also work.
Even though antibiotics work most of the time, Karen Vanderhoof-Forschner, founder of the Connecticut-based Lyme Disease Foundation, worries because data from animal studies suggest that treatment does not always make infection go away.
And if the initial infection is not adequately treated, the bacteria can lurk in the joints and the nervous system, producing chronic Lyme disease -- even years later.
In some people, the result is arthritis in the knee, in others, it's a brain problem called encephalopathy that leads to memory impairment and irritability.
Still others develop pain, numbness and tingling in the hands and feet.
It's still unclear whether these problems result from a flareup of a latent infection or, as may happen with arthritis, from an auto-immune attack in which the body attacks tissues harboring the spirochete.
For chronic Lyme, Dr. Sam Donta, an infectious disease specialist at Boston Medical Center and the Boston Veterans Affairs Medical Center, advocates long-term treatment -- six months or more -- with oral antibiotics such as tetracycline or an erythromycin-like drug that can kill bacteria inside cells.
"My advice is that if a patient starts to improve after two weeks, don't stop. Keep going until he's all better," he says.
Other specialists advocate long-term treatment with intravenous antibiotics, which may penetrate the nervous system better.