Database enables diagnosis of rare diseases

College Station, Texas- When Craig Carter, DVM, contracted brucellosisthrough occupational exposure, and doctors failed to help, he flipped theswitch on his computer.

Carter, head of epidemiology and informatics for the Texas VeterinaryMedical Diagnostic Laboratory at Texas A&M, wrote a computer programto help physicians diagnose rare diseases.

He turned to the computer for help after six consults with doctors providedno answers. Because brucellosis normally affects cattle, none of the doctorsrecognized the disease.

Carter finally was able to diagnose himself through analyzing his laboratoryblood test results.

"Many diseases caused by infectious agents or parasites spread fromanimals to humans present difficult diagnostic challenges because they areso rare in people," he says. "Physicians can overlook, misinterpretor disregard important clues that could lead to an initial diagnosis becausethey are unfamiliar with these diseases.

"That's when I got the idea that a computer diagnostic databasemight be helpful in pinpointing the identity of such diseases," Cartersays.

He and colleague Texas A&M scientist Norman Ronald modified a computerdiagnostic program designed originally for dogs and cats, and built a searchabledatabase of more than 200 infectious and parasitic diseases common to animalsand humans.

In 1997 a laboratory successfully tested the program on several hundredactual cases of brucellosis, according to published results in the Centersfor Disease Control journal, Emerging Infectious Diseases, so the authorsdecided to expand that program. Ronald is developing data for more than300 infectious diseases.

Information on each disease includes a description of symptoms, clinicaland laboratory findings, recommended treatment and a bibliography. Cartersays the Windows-based version will be available soon over the Internetor on CD-ROM. Physicians will be able to use the program to locate fulldescriptions of any of the diseases in the database.

Physicians can also input information about a patient, including medicalhistory, physical exam findings and laboratory tests.

"The program will then generate a list of possible diagnoses,"he says. "The great thing is that a doctor can keep inputting additionaldata and narrow the possible diagnosis."

In the 1997 study, physicians using the program could construct a differentialdiagnosis within three minutes.