St. Louis, July 15, 1999 -- Researchers have discovered a new form of a tick-borne disease that can be fatal in humans. This finding provides more insight into ehrlichiosis, first identified in humans in the United States in 1986.
A bacterium called Ehrlichia ewingii causes ehrlichiosis in dogs, cattle and other animals. But in the past few years, four people exposed to ticks in Missouri have contracted the disease from this bacterium.
"We want people to know that ehrlichiosis is in Missouri, Arkansas and southern Illinois," said Gregory A. Storch, M.D., professor of pediatrics at Washington University School of Medicine in St. Louis. "If someone is bitten by a tick and feels sick afterward, he or she should contact a physician as soon as possible and make sure the physician knows about the exposure."
The researchers report their findings in the July 15 issue of The New England Journal of Medicine. The lead authors are Storch and Richard S. Buller, Ph.D., research instructor of pediatrics.
The symptoms of ehrlichiosis resemble the flu, and they include fever, malaise, headache and muscle and joint pain. They usually appear 7 to 10 days after a tick bite. Dog ticks, deer ticks and the Lone Star tick are known to spread the disease.
Ehrlichiosis can be successfully treated with antibiotics. But someone who does not receive treatment can develop serious liver and lung problems that can cause organ failure.
Two other Ehrlichia species previously have been identified in the United States. E. chaffeensis, first detected in 1986, also is endemic in Missouri. Infecting a special white blood cell called a mononuclear cell, it causes human monocytic ehrlichiosis. In 1994, a new form of human ehrlichiosis called human granulocytic ehrlichiosis surfaced. This form involves a white blood cell called a granulocyte.