Lyme disease is the most common illness transmitted by animals or insects in the United States. The U.S. Centers for Disease Control and Prevention estimates more than 300,000 people per year get Lyme disease, which spreads to humans via the bite of black-legged ticks (also called deer ticks). Most cases of Lyme can be successfully treated with a course of antibiotics, but some people continue to report non-specific symptoms like fatigue or joint paint after undergoing treatment. This condition is called “post-treatment Lyme disease syndrome” or “post-Lyme disease syndrome.” Because Lyme can be difficult to diagnose and lead to complications if left untreated, experts are looking to stop the disease in its tracks. Here’s how researchers are investigating new ways to prevent the spread of Lyme. Treating Lyme Disease with Antibiotics Lyme disease is caused by the bacterium Borrelia burgdorferi. (Researchers are studying other recently discovered strains of Borrelia linked to Lyme.) Bacteria are highly susceptible to antibiotic drugs, so Lyme treatment generally consists of a course of common antibiotics like amoxicillin. The vast majority of people require no further treatment. Animal studies have confirmed, however, that antibiotics do not always destroy all the B. burgdorferi in these non-human species, and this could be why some people develop a post-Lyme syndrome. Researchers continue to investigate this possibility. Meanwhile, other current Lyme disease research is investigating potential vaccines for humans and even genetic engineering designed to stop the bacteria’s transmission by rodents. A Vaccine for Lyme Disease? In the 1980s, a major pharmaceutical company developed a vaccine for Lyme disease. Randomized controlled trials in humans showed the vaccine to be 76 to 92% effective in preventing Lyme disease after a series of three injections. Though the duration of effectiveness of the vaccine was not examined, people who received the injections in studies reported no serious side effects. Despite increasing rates of Lyme disease in the United States, sales of the vaccine declined throughout the 1990s, and the manufacturer stopped production in the early 2000s following legal issues. Today, another pharmaceutical company is developing a Lyme vaccine, which has recently been approved for Phase I clinical trials in the U.S. It could take many more years to determine if the vaccine is safe and effective. Preventing Lyme Transmission Through Genetic Engineering Scientists are studying ways to prevent the spread of Lyme to humans by blocking black-legged ticks from becoming infected in the first place. Lyme disease does not originate in ticks. Instead, they pick it up from infected mice. Black-legged ticks lay eggs that produce larvae that must feed on blood to survive. These tick larvae commonly attach to mice, and they ingest the B. burgdorferi bacterium as they feed on these infected rodents. Researchers are looking at various ways to inoculate wild rodent populations against B. burgdorferi, so that ticks cannot pick up Lyme disease from them and subsequently spread the bacteria to humans. For example, seeding rodent-populated areas with oral vaccine food pellets might inoculate the mice against Lyme. Similar preventive research efforts include altering the DNA of various rodent species to make them immune to B. burgdorferi. These genetic engineering efforts will require many more years of research to yield results, however. Taking Steps to Prevent Lyme Until researchers develop a safe and effective vaccine against Lyme disease or find a method to prevent the bacteria’s spread among tick and rodent populations, your best defense against the disease is prevention. Before you go hiking in any Lyme-prone areas, be sure to use an insect repellent containing DEET to help ward off ticks. Tuck your pant legs into your socks or boots to make it difficult for ticks to reach your skin. After hiking, remove your clothing carefully (and preferably outdoors), shaking out each item to dislodge any tiny ticks that may be hiding in the folds of your garments. And inspect your skin very thoroughly for ticks, removing any you find. Antibiotics remain an effective treatment for Lyme disease, but no one wants to get sick unnecessarily. Eventually researchers may find a way to make Lyme disease a thing of the past.