Lyme Case Definition
2008 National Lyme
Disease Case Definition
Lyme Disease
Surveillance Reporting Forms
About Case Definitions & Clinical Diagnosis
Lyme Disease is a Mandatory Reportable Disease in Iowa
Reporting of all nationally notifiable
diseases, including Lyme disease, is based on standard surveillance
case definitions developed by the Council of State and Territorial
Epidemiologists (CSTE) and CDC. The usefulness of public health
surveillance data depends on its uniformity, simplicity, and
timeliness. Surveillance case definitions establish uniform criteria
for disease reporting and should not be used as the sole
criteria for establishing clinical diagnoses, determining the
standard of care necessary for a particular patient, setting
guidelines for quality assurance, or providing standards for
reimbursement.
In 1982, systematic surveillance for Lyme disease was initiated
by CDC and was required nationally by 1991. Reported cases
meeting the case definition of Lyme disease are submitted
electronically by state health departments to the Centers for
Disease Control. Health-care providers in Iowa are required to
report information regarding newly diagnosed cases of Lyme disease
to the Iowa Department of Public Health. In Iowa, diagnostic
laboratories are also required by law to report all positive Lyme
disease test results to the health department. Because limited
patient information is usually provided with the laboratory results,
health department staff must follow up with health-care providers
and collect the clinical information necessary to determine if these
cases meet the case definition.
Effective January 1, 2008
Important: This surveillance case
definition was developed for national reporting of Lyme
disease; it is not intended to be used in clinical
diagnosis.
Case classification of
Lyme Disease (Borrelia burgdorferi):
Confirmed:
a) a case of EM with a known exposure (as defined
below), or
b) a case of EM with laboratory evidence of infection
(as defined below) and without a known exposure or
c) a case with at least one late manifestation that has
laboratory evidence of infection.
Probable: any other case of
physician-diagnosed Lyme disease that has laboratory
evidence of infection (as defined below).
Suspected:
a) a case of EM where there is no known exposure (as
defined below) and no laboratory evidence of infection
(as defined below), or
b) a case with laboratory evidence of infection but no
clinical information available (e.g. a laboratory
report).
Lyme disease reports will not be considered cases if the
medical provider specifically states this is not a case
of Lyme disease, or the only symptom listed is "tick
bite" or "insect bite."
Clinical presentation
A systemic, tick-borne disease with protean
manifestations, including dermatologic, rheumatologic,
neurologic, and cardiac abnormalities. The best clinical
marker for the disease is erythema migrans (EM), the
initial skin lesion that may occur in patients.
For purposes of surveillance, EM is defined as a skin
lesion that typically begins as a red macule or papule
and expands over a period of days to weeks to form a
large round lesion, often with partial central clearing.
A single primary lesion must reach greater than or equal
to 5 cm in size across its largest diameter. Secondary
lesions also may occur. Annular erythematous lesions
occurring within several hours of a tick bite represent
hypersensitivity reactions and do not qualify as EM. For
most patients, the expanding EM lesion is accompanied by
other acute symptoms, particularly fatigue, fever,
headache, mildly stiff neck, arthralgia, or myalgia.
These symptoms are typically intermittent. The diagnosis
of EM must be made by a physician. Laboratory
confirmation is recommended for persons with no known
exposure.
For purposes of surveillance, late manifestations
include any of the following when an alternate
explanation is not found:
Musculoskeletal system.
Recurrent, brief attacks (weeks or months) of objective
joint swelling in one or a few joints, sometimes
followed by chronic arthritis in one or a few joints.
Manifestations not considered as criteria for diagnosis
include chronic progressive arthritis not preceded by
brief attacks and chronic symmetrical polyarthritis.
Additionally, arthralgia, myalgia, or fibromyalgia
syndromes alone are not criteria for musculoskeletal
involvement.
Nervous system.
Any of the following, alone or in combination: lymphocytic meningitis;
cranial neuritis, particularly facial palsy (may be
bilateral); radiculoneuropathy; or, rarely,
encephalomyelitis. Encephalomyelitis must be confirmed
by demonstration of antibody production against Borrelia
burgdorferi in the cerebrospinal fluid (CSF), evidenced
by a higher titer of antibody in CSF than in serum.
Headache, fatigue, paresthesia, or mildly stiff neck
alone, are not criteria for neurologic involvement.
Cardiovascular system.
Acute onset of high-grade (2nd-degree or 3rd-degree) atrioventricular
conduction defects that resolve in days to weeks and are
sometimes associated with myocarditis. Palpitations,
bradycardia, bundle branch block, or myocarditis alone
are not criteria for cardiovascular involvement.
Laboratory evidence
For the purposes of surveillance, the definition of a
qualified laboratory assay is (1) a positive culture for
B. burgdorferi, or
(2) two-tier testing interpreted using established
criteria [1], or
(3) single-tier IgG immunoblot seropositivity
interpreted using established criteria [1-4].
Exposure
Exposure is defined as having been (less than or equal
to 30 days before onset of EM) in wooded, brushy, or
grassy areas (i.e., potential tick habitats) in a county
in which Lyme disease is endemic. A history of tick bite
is not required.
Disease endemic to county
A county in which Lyme disease is endemic is one in
which at least two confirmed cases have been acquired in
the county or in which established populations of a
known tick vector are infected with B. burgdorferi.
Source: January 9, 2008
United States Department of Health and Human Services
Centers for Disease Control and Prevention
National CDC Lyme Disease Case Report Form
Iowa Department of Public Health Lyme Disease Case Report Form
(Note: Information present on the CDC LD Case Report form regarding
pregnancy and Equivocal test results has been removed by IDPH.)
“No surveillance case definition is 100% accurate. There will always
be some patients with Lyme disease whose illness does not meet the
national surveillance case definition. For this reason, CDC has
stated repeatedly that the surveillance case definition is not a
substitute for sound clinical judgment. Given other compelling
evidence, a physician may choose to treat a patient for Lyme disease
when their condition does not meet the case definition.”
Testimony Statement by
Paul Mead, M.D., M.P.H. Medical Epidemiologist, Division of
Vector-Borne Infectious Diseases, National Center for Infectious
Diseases, Center for Disease Control and Prevention, U.S. Department
of Health and Human Services
Hearing: CDC's Lyme Disease
Prevention and Control Activities before the Connecticut Department
of Public Health and the Connecticut Attorney General's Office
Source: United States Department of Health and Human Services
http://www.hhs.gov/asl/testify/t040129.html
"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)."
From CDC Website:
http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5317a4.htm
Source: MMWR Weekly
May 7, 2004 / 53(17);365-369
“The case definitions contained in this report establish uniform
criteria for disease reporting and should not be used as the sole
criteria for establishing clinical diagnoses, determining the
standard of care necessary for a particular patient, setting
guidelines for quality assurance, or providing standards for
reimbursement. Use of additional clinical, epidemiologic, and
laboratory data may enable a physician to diagnose a disease even
though the formal surveillance case definition may not be met.”
“This surveillance case definition was developed for national
reporting of Lyme disease; it is not intended to be used in clinical
diagnosis.”
From the CDC Website:
http://www.cdc.gov/mmwr/preview/mmwrhtml/00047449.htm
Source:
MMWR
May 02, 1997 / 46(RR10);1-55
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