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Physician Reporting of Lyme Disease -- Connecticut, 1991-1992

Although disease reporting by physicians is an essential component of public health surveillance, the extent of physician participation in reporting specific diseases is not routinely assessed. As part of an evaluation of Lyme disease (LD) surveillance, the Connecticut Department of Health Services (CDHS) conducted a study to determine the number and specialty of Connecticut physicians who reported LD cases in 1991 and/or 1992. This report summarizes the results of this study.

To characterize physician reporting of LD, the CDHS expanded the LD surveillance database to include the names, towns, and license numbers of 4570 licensed physicians from four primary-care specialties: internal medicine (2520), general/family practice (1096), pediatrics (839), and dermatology (115). This primary-care physician group was a subset of the 9185 physicians (excluding physicians in residency programs) licensed by the CDHS as of January 30, 1992. If LD was reported by a physician not on the primary-care physician list, the name was checked against the complete list of licensed physicians.

From January 1, 1991, through December 31, 1992, 2952 cases meeting the CSTE/CDC surveillance case definition for LD (1) were reported to the CDHS. Of these, 2432 (82%) were reported by physicians from the four primary-care specialties and 59 (2%) from physicians in other specialties (Table 1). A total of 359 (12%) cases was reported by either a group practice; a hospital, laboratory, or clinic; or another state health department. Sixty-seven (3%) were reported with no physician or practice name listed, and 35 (1%) were reported by physicians whose license numbers could not be determined.

Of the 4570 physicians from the four specialties, 341 (7%) reported LD in 1991 and 313 (7%) reported cases in 1992 (Table 2). Twenty-five physicians reported 43% to 62% of the cases in five counties.

Reported by: PA Mshar, SH Ertel, ML Cartter, MD, JL Hadler, MD, State Epidemiologist, Connecticut State Dept of Health Svcs. Bacterial Zoonoses Br, Div of Vector-Borne Infectious Diseases, National Center for Infectious Diseases, CDC.

Editorial Note

Editorial Note: LD was first recognized in 1975 in Connecticut; the disease is endemic in each of Connecticut's eight counties, and the state rate of 54 cases per 100,000 population was the highest reported in the United States in 1992 (2). In November 1991, in collaboration with CDC, the CDHS began active surveillance for LD in two areas of the state and continued passive, physician-based surveillance in other areas. In 1992, 632 (36%) cases were reported by the 127 physicians in the active surveillance study.

The finding that only 7% of physicians in selected primary-care specialties in Connecticut reported LD in 1991 and/or 1992 suggests that most primary-care physicians in the state have not diagnosed cases of LD and/or that underreporting of cases by physicians is common. Of the 2952 LD cases reported, 2432 (82%) were reported by primary-care physicians: general practice/family medicine (46%), internal medicine (32%), and pediatric (21%) specialties. A limited number of cases was reported by dermatologists (1%), even though the earliest and most characteristic sign of LD is a large, expanding, annular dermatitis (erythema migrans), usually arising 3-30 days following tick bite (3).

As the findings in Connecticut indicate, a physician-based passive system of LD surveillance may be sensitive to small changes in reporting practices. Many of the cases in Connecticut were reported by a small group of physicians.

The findings in this report did not directly assess underreporting. Additional studies are needed to determine the percentage of LD cases that are diagnosed by physicians but not reported to local and state health departments.

Physician participation is critical in public health surveillance efforts. Surveillance should be improved by educating physicians, especially those in primary-care specialties, about the importance of reporting cases of notifiable diseases, including LD, and other selected health events.


  1. CDC. Case definitions for public health surveillance. MMWR 1990;39(no. RR-13):19-21.

  2. CDC. Lyme disease surveillance -- United States, 1991-1992. MMWR 1993;42:345-8.

  3. Steere AC, Bartenhagen NH, Craft JE, et al. The early clinical manifestations of Lyme disease. Ann Intern Med 1983;99:76-82.

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