Lyme Disease

Lyme Disease
Source: The National Institute of Allergy and Infectious Diseases (NIAID)

Lyme disease was first reported in 1975 after researchers investigated why unusually large numbers of children were being diagnosed with juvenile rheumatoid arthritis in Lyme, Connecticut, and two neighboring towns. Scientists soon discovered the disease was caused by a corkscrew-shaped bacterium called Borrelia burgdorferi passed to humans through the bite of a tick. The bacterium is carried by the deer tick in the eastern and central United States and by the Western black-legged tick on the Pacific coast.

To view an online version of NIAID’s publication titled Lyme Disease: The Facts, The Challenge, click here.

In 1999, 16,273 cases were reported to the Centers for Disease Control and Prevention.1 In the United States more than 90 percent of all reported cases occur in the Northeast, mid-Atlantic, and the upper Midwest. Few cases have been reported in northern California and remaining states.

The first sign of Lyme disease is often a circular or bullseye-like rash appearing at the site of a tick bite within a few weeks of the bite. Sometimes the rash is the first sign a person has been bitten. As the rash progresses it can appear on other sites of the body. The disease is easily cured at this stage with antibiotics, so careful attention to the symptoms is critical for proper care. If left untreated, many people develop pain and swelling in the joints, which may progress to chronic arthritis. In some cases, neurological symptoms also appear.

To reduce the risk of infection, a Lyme disease vaccine (LYMErix®) is available for use by people who live in endemic areas and are at high risk for developing the disease. NIAID Research For a detailed summary of selected NIAID research on Lyme disease, click here. Highlights of Lyme disease research include:

Vaccine Research

Michael Norgard, Ph.D., of the University of Texas Southwest Medical Center, and James Miller, Ph.D., of the University of California in Los Angeles, seek to understand how B. burgdorferi causes disease and to reveal properties of the bacterium that might be used for new Lyme disease vaccines.

Treatment of Chronic Lyme Disease

At the NIAID Bethesda campus, Adriana Marques, M.D., studies patients with suspected Lyme disease. Her research seeks to determine if the signs and symptoms associated with Lyme disease, particularly neurologic symptoms, are caused by ongoing Borrelia infection or by other disease processes.

Mark Klempner, M.D., from Boston University Medical Center, has recently completed an NIAID-supported randomized, controlled trial comparing 90-day antibiotic treatment to placebo for people who continue to have symptoms following the recommended antibiotic treatment for acute Lyme disease. Treatment with intravenous and oral antibiotics for 90 days did not improve symptoms when compared to placebo. For more information on the study, go here.

Interactions between People and Ticks

Stephen Wikel, Ph.D., at the University of Connecticut School of Medicine, and Yale University’s Fred Kantor, M.D., analyze tick salivary proteins for their role in Borrelia transmission. These proteins display a fascinating range of functions, from inhibiting the immune system to numbing the sensation associated with a tick bite. Furthermore, animals and humans who have had several tick encounters become immune and the tick does not remain attached for very long. In the laboratory, when Borrelia-infected ticks are placed on a tick-immune animal, they fail to transmit disease. By studying the molecular components of tick saliva, the researchers hope to identify new targets for vaccines that may prevent the spread of several tick-transmitted diseases.

Interactions between People and the Lyme Bacterium

Claude Garon, Ph.D., a scientist in NIAID’s Rocky Mountain Laboratories (RML) in Hamilton, Mont., uses microscopy to study how Lyme bacteria adhere to and infect nerve and other cells.

Ira Schwartz, Ph.D., an NIAID-supported scientist at New York Medical College, investigates how genetic variations within B. burgdorferi affect the ability of the microbe to spread through the blood, a key step of infection. His laboratory has also developed a potential DNA-based diagnostic test that will help physicians rapidly confirm Lyme disease in patients.

Yale University’s Stephen Malawista, M.D., who initially discovered Lyme disease in 1975, continues to conduct research into the disease. With his collaborator, Dr. Ruth Montgomery, the laboratory focuses on an apparent paradox. Macrophages and neutrophils, large white blood cells that eat and destroy bacteria, take up and kill the B. burgdorferi rapidly in the test tube. But in some animals and people, the bacteria persist in skin, multiply, and spread despite the presence of the immune cells. Drs. Malawista and Montgomery have begun a comprehensive examination of macrophage killing mechanisms to address this conundrum.

Interactions between Ticks and the Lyme Bacterium

RML researchers study how the Lyme bacteria interacts with ticks. Tom Schwan, Ph.D., and colleagues study how B. burgdorferi adapts to and develops within its tick host. His laboratory also seeks to improve diagnostic tests for Lyme disease. Patricia Rosa, Ph.D., takes a molecular genetic approach to investigate how the microbe moves between ticks and humans, and what environmental cues are responsible for this movement.

Other Research

Richard Ostfeld, Ph.D., of the Institute of Ecosystem Studies in Millbrook, N.Y., investigates the relationship between ecological factors such as acorn production and biodiversity and the incidence of Lyme disease. His research is discussed in more detail here. The University of Rhode Island’s Thomas Mather, Ph.D., studies the population distribution of ticks carrying B. burgdorferi and other infectious microbes. His lab identifies non-human vertebrate hosts of these pathogens and seeks to define the risk of disease transmission based on ecological models.

John McLaughlin, Ph.D., of IPM Technologies in Portland, Oregon, is developing a trap that uses sexual attractants to lure ticks in, where they will be killed by small amounts of chemicals. His team has identified several pheromones that serve as attractants and tests are ongoing in a variety of settings. Such a trap would selectively destroy ticks without requiring large-scale pesticide spraying.

Scientists at Immunetics, Inc. of Cambridge, Massachusetts, have received a license from the Food and Drug Administration (FDA) for the new kit called the C6 B. burgdorferi (Lyme) ELISA Kit. The FDA license means the kit can be used by physicians to diagnose Lyme disease in patients. The kit, developed in part with NIAID funding, detects antibodies specific to B. burgdorferi. It works by detecting a chemical marker universal to all Borrelia bacteria. In clinical trials with volunteers, the new test was shown to reduce the number of false positive results as compared to the current screening methods.

Additional links:

NIAID information on Lyme disease and other tick-borne illnesses
CDC information on Lyme disease

1. Centers for Disease Control and Prevention. Summary of Notifiable Diseases, United States, 1999. Morbidity and Mortality Weekly Report, 2001;48:1-104.