CDC and State Health Departments Quotes

Cases of Lyme Missed- Not Reported

CDC- “Surveillance for LD is subject to several limitations. Studies from the early 1990s suggested that LD cases were underreported by six to 12-fold in some areas where LD is endemic (2,3); the current degree of underreporting for national data is unknown. In addition, differences in the demographics of reported cases among states with above- and below-average incidence suggest variation in diagnostic and reporting practices among states. Clinicians are reminded that the LD case definition was developed for surveillance purposes and might not be appropriate for clinical management of individual patients(1).”


J Infect Dis. 1996 May;173(5):1260-2.

The public health impact of Lyme disease in Maryland.

Coyle BS, Strickland GT, Liang YY, Peña C, McCarter R, Israel E.


Dept. of Epidemiology and Preventive Medicine, University of Maryland School of Medicine, Baltimore 21201, USA.


The purpose of this study was to estimate the health burden imposed by Lyme disease (LD) in Maryland during 1992 and 1993. A cross-sectional 1-in-15 survey of physicians (total, 1200) in Maryland was conducted to estimate the incidence of diagnosed LD, presumptive cases of LD, patients with tick bites, and diagnostic tests ordered for LD. Results show that LD is underreported by 10- to 12-fold in Maryland, that 80% of cases are managed by primary care physicians, and that there is discordance between the actual clinical treatment of patients and the recommended approach. In addition, the much greater numbers of patients treated for presumptive LD, seen and given prophylaxis for tick bites, and having diagnostic tests indicate that real and perceived LD is a far greater public health problem and uses more medical resources than official surveillance data suggest.

PMID: 8627082 [PubMed - indexed for MEDLINE]


“Therefore, LD was underreported by 10-fold during 1992 and by 12-fold in 1993, as estimated by two independent methods of calculation.”


J Public Health Manag Pract. 1996 Fall;2(4):61-5.

Underreporting of Lyme disease by Connecticut physicians, 1992.

Meek JI, Roberts CL, Smith EV Jr, Cartter ML.


Connecticut Department of Public Health, New Haven, USA.


To determine the magnitude of underreporting of Lyme disease, a random sample of Connecticut physicians was surveyed in 1993. The magnitude of underreporting was assessed by comparing physician estimates of Lyme disease diagnoses with reports of Lyme disease sent by physicians to the Connecticut Lyme disease surveillance system. Complete questionnaires were returned by 59 percent (412/698) of those surveyed. Of the 224 respondents who indicated that they had made a diagnosis of Lyme disease in 1992, only 56 (25 percent) reported a case of Lyme disease that year. Survey results suggested that, at best, only 16 percent of Lyme disease cases were reported in 1992. Physician underreporting of Lyme disease underestimates the public health impact of Lyme disease.

PMID: 10186700 [PubMed - indexed for MEDLINE]


MMRW 2002- "In North America, Lyme disease and endemic relapsing fever pose the greatest threat to human health and have received the most attention of the borrelial diseases. Approximately 14,000 cases of Lyme disease are reported in the United States each year; however, the actual number of cases may be 10-fold higher (2)."


"In January 1998, to study the effectiveness of a newly released Lyme disease vaccine, mandatory laboratory surveillance was implemented that required all laboratories to report positive and equivocal results to CDPH. Follow-up, conducted by CDPH staff, involved sending a letter and supplemental report form to the ordering physician. To assist the physician, demographic and patient-identifying information from the laboratory report was incorporated into the form. Mandatory laboratory surveillance ended after 2002 when the Lyme disease vaccine was removed from the market.

During 1996–2007, CDPH staff processed 87,174 Lyme disease reports, of which 7,278 (8.3%) were duplicate entries and were removed from the database. A total of 79,896 individual reports were analyzed. Of these, 43,767 (54.8%) were reported through mandatory laboratory surveillance, 19,350 (24.2%) through passive physician surveillance, 13,040 (16.3%) through active physician surveillance, and 3,739 (4.7%) through enhanced laboratory surveillance.Overall, 33,457 (41.9%) reports were classified as cases, and 26,318 (32.9%) as not cases; 20,121 (25.2%) were lost to follow-up (Table 1). Except for calculation of PPV, reports classified as lost to follow-up were excluded from further analyses."

“First, because LD is reported through passive surveillance, LD is underreported, and the distribution anddemographics of reported cases could be biased. Second, LD is underreported in areas where disease is endemic and might be overreported in areas where disease is nonendemic."

Last Updated- April 2019

Lucy Barnes