Bacteria able to linger long term.

• Position: Lyme Disease

The bacteria that cause Lyme disease, the most common tick-borne illness in the U.S., can linger in tissues long after a full round of antibiotic treatment is completed, according to a report in the journal Antimicrobial Agents. Scientists caution that the discovery does not suggest the presence of chronic disease, nor does it support extended use of antibiotics to treat Lyme disease in humans.

However, they say, the results of this study do set the stage for controlled laboratory research investigating potential therapies for persistent Lyme disease infections. "Lyme disease is a tough nut to crack. The bacterium Borrelia burgdorferi has evolved to evade the body's immune system, so it's not surprising that it can also evade antibiotics" explains Stephen Barthold, lead researcher on the study.

"It's important to note that the numbers of residual bacteria identified in this study were very low and there was no evidence that they were causing inflammation. Their presence shouldn't be misconstrued as a sign of chronic disease"

Borrelia burgdorferi, the corkscrew-shaped bacterium that triggers

Lyme disease, is transmitted to humans and animals through bites from infected deer ticks. In the U.S., Lyme disease is most prevalent in the northeastern and Great Lakes states, and is present to a lesser extent in Northern California. Other high-risk Lyme disease areas are scattered throughout the nation, usually in shady, moist deciduous forests where the carrier ticks and their wildlife hosts flourish.

Symptoms of Lyme disease are highly variable and may include fever, headache, fatigue, and skin rash. If the infection is not treated, it can spread to the joints, heart, and nervous system. Usually, Lyme disease can be treated successfully with about four weeks of antibiotics. Treatment is most successful during the early stages of infection. A few patients, particularly those treated during late infection, may experience persistent or recurring symptoms after the antibiotic treatment is finished, in which case a second round of antibiotics may be prescribed.

According to the Centers for Disease Control and Prevention, Atlanta, antibiotic treatment above and beyond one repeat round has not been shown to be beneficial and has been linked to serious complications, including death. Many of those involved with Lyme disease--including patients, physicians, researchers, and health insurance companies--are divided over how to treat the ailment when it...