In the September 2003 issue of the journal Emerging Infectious Diseases, investigators at Rocky Mountain Laboratories (RML) in Hamilton, Montana, and their collaborators describe this outbreak and the results of laboratory and clinical investigations.

"Given the 100-year history of research into ticks and tick-borne diseases in Montana, we are gratified to have helped solve the mystery of this outbreak and to have identified a focus of this disease as well as the bacterium and tick in our back yard," states Tom G. Schwan, Ph.D., lead investigator of the study. RML, which began by conducting pioneering studies in Montana on Rocky Mountain spotted fever, is part of the National Institute of Allergy and Infectious Diseases (NIAID), a component of the National Institutes of Health in Bethesda, MD.

"This investigation demonstrates once again the potential for diseases to emerge unpredictably in areas where they have not been recognized previously," notes Marshall Bloom, M.D., associate director of RML. "These findings will also alert health care providers in this region that relapsing fever bacteria may cause a recurrent febrile illness, which is curable when recognized and treated promptly with antibiotics."

The mystery presented itself between July and August 2002, when five of 20 people became ill during or after visiting a cabin on an island in Flathead Lake in western Montana. RML investigators and tick experts Dr. Schwan and Paul Policastro, Ph.D., worked with physicians in Seattle; Montana State Epidemiologist Todd Damrow, Ph.D.; the Lake County Health Department; and the curator of the U.S. National Tick Collection to determine the cause of the outbreak.

The patients, between 5 and 54 years old, experienced
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NIH/National Institute of Allergy and Infectious Diseases
26-Aug-2003