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CSTE
Position
Statements 2000
ID-#3 COMMITTEE:
Infectious Disease TITLE:
Changes in the case definition for human ehrlichiosis, and addition of a new
ehrlichiosis category as a condition placed under surveillance according to the
National Public Health Surveillance System (NPHSS) ISSUE:
Human ehrlichiosis is an emerging tick-borne infectious disease in the United
States. Human ehrlichiosis caused by Ehrlichia chaffeensis (human
monocytic ehrlichiosis [HME]) and Ehrlichia
phagocytophila (human
granulocytic ehrlichiosis [HGE]) were placed under national surveillance
according to NPHSS via CSTE position statement #6 in 1998; previously, CSTE
position statement #17 in 1996 had described a uniform case definition for
reporting purposes. Since that time, advances in laboratory diagnostic criteria
have expanded to include a range of available tests. In addition, a third Ehrlichia
species (Ehrlichia ewingii) has been
shown to cause disease in humans, and it is possible that additional pathogenic Ehrlichia
species will be identified in the future. Finally, occasional problems with the
classification of some ehrlichiosis cases have occurred because of
cross-reactivity in serologic assays used to diagnose these diseases. There is a
need to revise the current case definition to clarify reporting criteria, and to
place cases caused by unspecified or novel Ehrlichia
species under national surveillance. POSITION
TO BE ADOPTED: CSTE
and NASPHV recommend:
GOALS
FOR SURVEILLANCE: HME
and HGE have been placed under surveillance according to NPHSS and over 600
cases were reported to state health departments in 1999. However, the current
case definition does not allow accurate reporting of cases when an etiologic
distinction between E.
chaffeensis and E.
phagocytophila is not made, or when disease is caused by E.
ewingii or a novel Ehrlichia species. At least
48 cases of unspecified ehrlichiosis reported to state health departments in
1999 could not be correctly submitted to the National Electronic
Telecommunications System for Surveillance (NETSS) under the current case
definition. The correct
classification and reporting of these cases is necessary to further define and
monitor the geographic boundaries for these diseases. METHODS
FOR SURVEILLANCE:
Clinician
and laboratory reporting. Core surveillance data should be forwarded to the
Centers for Disease Control and Prevention (CDC) via the National Electronic
Telecommunications System for Surveillance (NETSS) for the purposes of national
surveillance. CASE
DEFINITION: Clinical
description A
tick-borne illness characterized by acute onset of fever, headache, myalgia,
and/or malaise. Nausea, vomiting, or rash may be present in some cases. Clinical
laboratory findings may include thrombocytopenia, leukopenia, and/or elevated
liver enzymes. Intracytoplasmic bacterial aggregates (morulae) may be visible in
the leukocytes of some patients. Three
categories of confirmed or probable ehrlichiosis should be reported: 1) human
ehrlichiosis caused by E.
chaffeensis (HME), 2) human ehrlichiosis caused by E.
phagocytophila (HGE), and 3) human ehrlichiosis (other or unspecified
agent), which includes cases that cannot be easily classified by available
laboratory techniques, and cases caused by novel Ehrlichia
species such as E.
ewingii. Laboratory criteria for diagnosis HME:
HGE:
Ehrlichiosis
(other or unspecified agent):
Case
classification
Probable:
a clinically compatible illness with either a single positive IFA titer (based
on cutoff titers established by the laboratory performing the test) or the
visualization of morulae in leukocytes. Confirmed:
a clinically compatible illness that is laboratory-confirmed. DATA
TO BE COLLECTED:
NETSS
Core Data and supplemental information PERIOD
OF SURVEILLANCE: Permanent,
with review of reporting needs every five years. COORDINATION
WITH OTHER ORGANIZATIONS: Agency
for Response: James
M. Hughes, MD Centers
for Disease Control and Prevention National
Center for Infectious Disease 1600
Clifton Road, NE M/S
C12 Atlanta,
GA 30333 Agencies
for Information: Association
of Public Health Laboratories (APHL) CONTACT
PERSON: Matthew
Cartter, MD, MPH Epidemiology
Program Infectious Diseases Division Connecticut
Department of Public Health 410
Capitol Ave. MS 11-EPI P.O.
Box 340308 Hartford,
CT 06106 Tel:(860)
509-7994 Fax:
(860) 509-7910 Email:
Matt.cartter@po.state.ct.us
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