|
.gif) |
Ehrlichiosis (HGE, HME, other or unspecified)
1996 Case Definition
Clinical description
A tickborne febrile illness most commonly characterized
by acute onset, accompanied by headache, myalgia, rigors and/or malaise.
Clinical laboratory findings may include intracytoplasmic microcolonies
(morulae) in leukocytes of peripheral smear, cerebrospinal fluid (CSF),
or bone marrow aspirate or biopsy, cytopenias (especially thrombocytopenia
and leukopenia), and elevated liver enzymes (especially alanine aminotransferase
or aspartate aminotransferase).
There are two clinically similar yet serologically
distinct forms of ehrlichiosis: a) human granulocytic ehrlichosis
(HGE), caused by infection with an Ehrlichia equi-like agent
and found primarily in the upper midwest and northeast, and b) human
monocytic ehrlichiosis (HME) caused by Ehrlichia chaffeensis infection
and found primarily in the southeastern quadrant of the United States.
Laboratory criteria for diagnosis
- Fourfold or greater change in antibody titer to Ehrlichia
spp. antigen by immunofluorescence antibody (IFA) test in
acute- and convalescent-phase specimens ideally taken greater
than or equal to 4 weeks apart. HME diagnosis requires E.
chaffeensis and HGE currently requires E. equi or
HGE-agent antigen, or
- Positive polymerase chain reaction assay. Distinct
primers are used for the diagnosis of HGE and HME, or
- Intracytoplasmic morulae identified in blood, bone
marrow, or CSF leukocytes, and an IFA antibody titer greater than
or equal to 64.
Case classification
Probable: a clinically
compatible case with either a single IFA serologic titer greater than
or equal to 64 or intracytoplasmic morulae identified in blood, bone
marrow, or CSF leukocytes
Confirmed: a clinically compatible case that
is laboratory confirmed
Comment
All laboratory testing should be conducted by experienced
personnel with appropriate training and should include appropriate controls
and reagents necessary for accurate etiologic diagnosis. States in which
cases of HGE and/or HME have occurred may submit reports to CDC
See also:
Printable
Version |
|
