Lyme disease, or Lyme borreliosis, is a debilitating disease caused by a corkscrew-shaped bacterium, a spirochete, named Borrelia burgdorferi.
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.
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.
We are interested in answering key questions that relate to Lyme disease, as it continues to increase in prevalence. These are:
To address these questions we use both monkey and mouse models of Lyme disease as well as ticks.