Study Shows Tick-Borne Disease Creates Telling Pattern On X-Rays

Now, a University of North Carolina at Chapel Hill medical scientist says both doctors and the public also should be aware of a tick-borne infection called ehrlichiosis, the cause of which in the United States was not recognized until 1986.

In studies on three North Carolina children who contracted ehrlichiosis, including one who died in 1996, Dr. Lynn A. Fordham has discovered the illness shows up on chest X-rays as increased fluid in the lungs. That finding may help doctors diagnose the condition earlier and, as a result, possibly treat it more effectively.

"Ehrlichiosis is usually mild with flu-like symptoms but can be rapidly fatal," said Fordham, assistant professor of radiology at the UNC-CH School of Medicine. "The infection should be considered when diagnosing acutely ill children with possible tick exposure and X-rays showing increased lung fluids not caused by a heart problem."

A report on the research will appear in the November issue of the American Journal of Roentgenology. Besides Fordham, UNC-CH authors are Drs. Charles J. Chung and Barbara B. Specter, assistant professors of radiology; David F. Merten, clinical professor of radiology; and David L. Ingram, professor of pediatrics.

"Ehrlichiosis is treatable, but needs to be diagnosed as rapidly as possible," Fordham said. "Doxycycline, an antibiotic, is effective, but doctors don't like to use it unless they have to because it can permanently discolor children's teeth."

X-raying patients transferred to intensive care units may give a quicker indication of the infection than detailed microscopic studies can, she said. Unfortunately, what is seen on X-rays is not unique to ehrlichiosis, but also occurs in other serious conditions such as organ failure, severe burns and drug reactions. Still, a few hours head start might mean the difference between life and death for a gravely ill child in an intensive care unit.

"The chance of getting any of these diseases can be reduced by decreasing exposure to ticks," Fordham said. "During tick season, people should wear light clothing, use insect repellents and check themselves and their children for ticks after being outdoors. If someone is bitten, record that information on a calendar and be sure to tell medical personnel about it if he or she develops a fever and flu-like symptoms within a few weeks."

Ehrlichiosis was first described in Algerian dogs in 1935, and Japanese scientists found that a bacterium caused a human form of the illness in 1956. Thirty years later, U.S. investigators discovered the first case of a different variety, human monocytic ehrlichiosis, at Fort Chafee, Ark. That infection chiefly occurs in the central and southeastern United States, while still another form, human granulocytic ehrlichiosis, chiefly is found in north central states.

Dog, deer and Lone Star ticks can carry ehrlichiosis bacteria, which infect and kill white blood cells, Forham said. Keeping leaves raked and bushes trimmed around homes can minimize shelter for mice and other small mammals to help keep down the tick population.