Injectable Antibiotic Protects Against Lyme Disease in Mice

By Alan Mozes
HealthDay Reporter
Saturday, April 5, 2008; 4:00 AM

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FRIDAY, April 4 (HealthDay News) -- One injection of a long-acting version of the antibiotic doxycycline appears to protect mice from developing the tick-borne illnesses Lyme disease or anaplasmosis, new animal research reveals.

The finding -- not yet replicated in people -- raises hope for developing a safer and more effective way to combat transmission of both diseases among humans.

"We're the first to show that you can use a sustained-release formulation of this antibiotic to completely inhibit both infections when transmitted simultaneously by ticks," said study author Dr. Nordin Zeidner, chief of the U.S. Centers for Disease Control and Prevention's Vector-Host Laboratory, in Fort Collins, Colo.

Zeidner stressed, however, that the treatment shouldn't be thought of as a vaccine for either disease but rather as a potentially novel method to inhibit infection following exposure.

"But this is, nevertheless, an important proof of concept," he added, "because we know that a lot of ticks infected with Lyme disease also carry this co-infection."

The study was published in the April issue of the Journal of Medical Microbiology.

Lyme disease is the most common tick-borne illness in the United States, with approximately 20,000 new cases diagnosed in 2006, according to the CDC. It's transmitted by blacklegged ticks infected with the bacterium Borrelia burgdorferi. The ticks are common in the upper Midwest and Northeastern regions of the United States and can also carry other diseases such as human granulocytic anaplasmosis, posing a risk for combined infections.

People infected with Lyme disease can experience flu-like fever, weakness, headache, fatigue, and skin rashes. If left untreated, the disease can spread to the joints, as well as to the heart and the nervous system. Symptoms of anaplasmosis can include fever, headache, lethargy, rashes and gastrointestinal problems, according to the CDC.

Efforts to develop a vaccine for either Lyme disease or anaplasmosis haven't met with much success. So, doctors stress prevention measures when outdoors, such as the use of insect repellants with DEET and covering up with clothing.