Originally created 10/09/01

Could your doctor tell if you have plague?

Could the doctor tell if you have anthrax or bubonic plague or brucellosis?

Although they may have read about them, most American doctors have never seen a patient with any of these infections and may well misdiagnose them.

This makes it hard for physicians to be the first line of defense against possible bioterrorism attacks that have drawn increased government and public concern in the wake of the Sept. 11 attacks.

Craig Carter, a veterinarian at Texas A&M University in College Station, knows all too well how easily doctors can be baffled by illnesses rarely seen in the United States. Not one of the six physicians he consulted after becoming infected with brucellosis in his lab were able to tell him what was wrong with him.

He finally diagnosed himself by analyzing his own blood tests.

"This is a problem across the board with rare diseases, particularly those that are transmitted from animals," Carter said. "My experience was a big motivation to help come up with a screening tool that doctors could use to help them jog their memory and maybe think about zebras rather than horses."

Carter, head of epidemiology and informatics at the Texas Veterinary Medical Diagnostic Laboratory, had already written a computer diagnostic program to help identify infections in dogs and cats that is sold through a company, Texas Medical Informatics Inc., that he and his colleagues set up in 1989.

Even as he continued to take steady doses of antibiotics in his battle against brucellosis, Carter and Texas A&M scientist Norman Ronald constructed a database of more than 220 infectious and parasitic diseases common to animals and humans.

As a patient describes symptoms and the doctor takes down vital signs and other medical information, everything is entered into a computer, which then presents the physician with a list of possible diseases, ranked by probability.

"The great thing is that a doctor can keep inputting additional information and keep narrowing the possible diagnosis," Carter said.

Carter took the first version of the program, completed in 1997, and tested it against the disease he had. Brucellosis is a bacterial infection that normally strikes cows, sheep and pigs. According to the federal Centers for Disease Control and Prevention, various strains of the bacteria also manage to infect about 100 people in the United States each year.

Brucellosis is not only rare, it also has many variable and nonspecific symptoms that match those of many other diseases, including the flu - fever, night sweats, headaches, back pain and physical weakness. Unchecked, it can infect most organs, including bone marrow, and produce arthritis-like symptoms, damage the lining of the heart and attack the central nervous system. It can cause depressive episodes in some people. The disease can be fatal.

Carter got the public health records of 200 Texans who had suffered brucellosis infections in recent years and entered the symptoms they had shown. "For every patient, brucellosis always popped up at or near the top of possibilities, at least in the top five.

"We calculated that the length of time needed to make a diagnosis would have been cut an average of 12 days in those patients -that's a significant length of time in medicine -while taking an average of three minutes' worth of data input by the doctor," Carter said.

His study, published by the CDC's journal Emerging Infectious Diseases, didn't attempt to calculate what kind of money and discomfort might have been saved had the disease been tagged sooner, "but the records showed some of the patients had endured some very intrusive, unnecessary procedures, like abdominal surgery, in attempts to find out what was wrong with them."

The software not only lists possible diseases, it also suggests which laboratory tests should be run to help confirm an infection and offers general advice on what drugs are most helpful in attacking the illness.

However, despite the study's good results, interest in the software hasn't been that strong. "Not that many doctors have been trained to use computers as tools in their practice, and there's a generational gap with a lot of them still unwilling to rely on the advice of a machine," Carter said.

He concedes that part of the problem may have been that the software so far has been available only in a DOS version, although a full Microsoft Windows-compatible versions will soon be out as a CD-ROM and for downloading over the Internet.

"With this renewed emphasis on the bioterrorism threat, maybe the interest level will change."

Although U.S. public health officials are on increased alert, whether a disease is spread through normal contact or maliciously, the public health system can only track outbreaks through reports of new or unusual illnesses filed by individual doctors.

"We feel this system could easily be used to screen people to see if their symptoms fit any of these agents that are being discussed as possible biological weapons," Carter said.

He added that his group would like to work with one of several existing physician-information Web sites to set up an online version of the screening tool that doctors could use and test when they feel stumped.

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