Lyme Disease

Lyme disease, or Lyme borreliosis, is a debilitating disease caused by a corkscrew-shaped bacterium, a spirochete, named Borrelia burgdorferi.

• It occurs in North America, Europe, and parts of Asia, including northern China. With over 300,000 estimated cases annually, Lyme disease is the most common tick-borne infection in North America.
• Lyme disease causes very diverse symptoms. In the disease’s earlier phases, it may induce skin rashes, arthritis, flu-like symptoms, facial paralysis, pain in nerves of the arms and legs, headaches, and meningitis. Later in the disease process it can cause chronic arthritis, forgetfulness and inability to concentrate or function productively.
• Most cases of early Lyme disease are successfully treated with antibiotics. However, if the disease remains undetected or is misdiagnosed and antibiotic therapy is delayed, the chances of successful treatment diminish considerably. Accurate diagnosis of Lyme disease is, therefore, very important.

Spirochete That Causes Lyme disease

Lyme disease is caused not just by one species of spirochete but by a group of spirochete species broadly named Borrelia burgdorferi sensu lato. In the U.S., only one species of spirochete causes Lyme disease. This species is called B. burgdorferi sensu stricto (in a strict sense). In Europe, other species that cause Lyme disease are named Borrelia afzelii and Borrelia garinii, in addition to B. burgdorferi sensu stricto.

As they infect humans and other animals, spirochetes live either in the blood or in tissues but do not invade blood or tissue cells like many parasites do for self-protection. Spirochetes remain exposed to attack by antibodies and cells of the immune system and yet, they survive. How spirochetes manage to survive in such a hostile environment is a result of their utilization of many immune evasion tactics.

Transmission

Lyme disease spirochetes are transmitted to humans and to other animals by ticks. The most common North American species of tick able to transmit B. burgdorferi spirochetes is Ixodes scapularis, also known as the deer tick. These ticks feed mainly on mice, which act as a reservoir host for spirochetes. The adult tick, however, prefers deer for its blood meal, hence the name "deer tick."

Ticks transmit the spirochete to humans and other animals when they take a blood meal. Spirochetes are delivered in the skin, together with tick saliva. Tick saliva contains multiple substances, many of which are believed to attenuate the immune response to the spirochete, thereby facilitating transmission.

Deer ticks able to transmit Lyme disease are common in Louisiana. Why Lyme disease is rare in Louisiana is not specifically known, but is likely related to the reservoir host ecology.

Our Research

We are interested in answering key questions that relate to Lyme disease, as it continues to increase in prevalence. These are:

• How can we make the diagnosis of Lyme disease more accurate?
• How do ticks attract the spirochetes sequestered in host tissues to the site of feeding
• How do Lyme disease spirochetes avoid or inhibit the immune response of the host?
• What are the mechanisms that enable Lyme disease spirochetes to cause cognitive impairment?
• What antimicrobial drugs or therapeutic treatments will eradicate the infection?
• What is the pathogenesis of Lyme neuroborreliosis?

To address these questions we use both monkey and mouse models of Lyme disease as well as ticks.

Contact

For more information about our Lyme disease research, please contact Dr. Monica Embers or Dr. Geetha Parthasarathy.