Anaplasmosis and Ehrlichiosis
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Rickettsial
infections are caused by a variety of bacteria, and are most often
transmitted to humans by infected fleas, lice, mites, and ticks.
Rickettsial infections include anaplasmosis, ehrlichiosis, Rocky
Mountain spotted fever, and typhus fever group.
Anaplasmosis
(Anaplasma phagocytophilum infection)
Anaplasmosis, previously known as human granulocytic
ehrlichiosis (HGE), is an illness caused by the bacterium Anaplasma
phagocytophilum. Anaplasmosis is transmitted to humans through the bite
of an infected deer or blacklegged tick (Ixodes scapularis), the same
tick that causes other tickborne diseases in Wisconsin including Lyme
disease. Illness occurs within 1-3 weeks after exposure to an infected
tick. Symptoms may include fever, chills, muscle pain, severe headache,
and fatigue. Clinical laboratory findings may include thrombocytopenia,
lymphopenia, leucopenia, and elevated live enzymes. If not treated,
anaplasmosis can lead to serious and occasionally fatal illness.
Anaplasmosis is the second most reported tickborne disease in Wisconsin.
Ehrlichiosis
(Ehrlichia chaffeensis, Ehrlichia ewingii and Ehrlichia
muris-like infection)
Ehrlichiosis is an illness caused by several species of
Ehrlichia (E. chaffeensis, E. ewingii and Ehrlichia
muris-like). In
Wisconsin, ehrlichiosis is transmitted to humans through a bite of an
infected deer or blacklegged tick (Ixodes scapularis), the same tick
that causes other tickborne diseases. Since 2008, there has been an
increase in reported cases of ehrlichiosis in Wisconsin. A new Ehrlichia
species (Ehrlichia muris-like) was discovered in Wisconsin and Minnesota
in 2009. Illness usually occurs between 5-10 days after exposure to an
infected tick. Symptoms may include fever, chills, muscle pain severe
headache, and fatigue. Less common signs and symptoms may include
nausea, vomiting, diarrhea, joint pains, confusion, and rash. Clinical
laboratory findings may include thrombocytopenia, lymphopenia,
leucopenia, and elevated live enzymes. Ehrlichiosis can be more severe
than anaplasmosis, and may involve the central nervous system, causing
life-threatening complications. The number of reported ehrlichiosis
cases is much lower than anaplasmosis in Wisconsin.
Tickborne diseases home
General information
Anaplasmosis
/ Ehrlichiosis fact sheet (PDF, 25 KB)
Prevention and control of tickborne
diseases
Anaplasmosis -
CDC
Ehrlichiosis -
CDC
Data and Statistics
Data by year
Information for health professionals
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This is a Wisconsin Disease Surveillance Category II disease:
Report to
the patient's local public health department electronically, through the Wisconsin
Electronic Disease Surveillance System
(WEDSS), by mail or fax using an Acute and Communicable Disease Case
Report F44151 (PDF,
167 KB) or by other means within 72 hours upon recognition of a
case. DHS
Communicable Disease Reporting
-
Wisconsin case reporting and public health follow-up
guidelines: Anaplasmosis / Ehrlichiosis
EpiNet (PDF, 44 KB)
-
Tickborne
Rickettsial disease case report form (PDF
Fillable,
494 KB)
- Laboratory
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Because Anaplasma and Ehrlichia infections can have similar signs and
symptoms, diagnostic tests are important to identify the specific agent
causing illness. All patients who warrant testing for Anaplasma should
also be tested for Ehrlichia. In WI, a panel testing for Anaplasma and
Ehrlichia should be performed. PCR is the preferred diagnostic test
because it is highly sensitive and specific during the acute disease
phase. PCR testing should be performed using EDTA whole blood collected
upon the initial physician's visit, prior to initiation of antibiotics.
Because testing for E. muris-like species is only currently available
commercial by PCR and not available by serology, it is important for
providers who routinely perform serologic testing to collect an
additional sample for PCR testing of E. muris-like species if this agent
is suspected.
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Serologic testing is the most common test performed in WI even though
it is less specific than the PCR test and cross-reactivity often occurs
among the Anaplasma and Ehrlichia agents. Serologic confirmation of A.
phagocytophilum or E. chaffeensis infection requires evidence of a
four-fold change in immunoglobulin G (IgG) specific antibody titer
between paired acute and convalescent sera tested by indirect
immunofluorescence assay (IFA). The acute sample should be collected
during the first week of illness and the convalescent collected 2-4
weeks later. IgM antibody test results are not as reliable as IgG test
results because IgM is less specific and can persist for a long period
of time (3). Because cross-reactivity between A. phagocytophilum and
E.
chaffeensis frequently occurs with serologic testing, the agent
demonstrating a higher titer (at least 4-fold) is the most likely agent
causing illness. If a laboratory routinely performs only peripheral
blood smears, the MDH and WDPH recommend that blood smear testing should
be accompanied by a PCR or an IFA test for more definitive results.
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Anaplasma
Laboratory Tests - CDC
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Ehrlichia Laboratory Tests - CDC
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Treatment
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Treatment for anaplasmosis and ehrlichiosis should not be delayed
while awaiting further laboratory test results, but should be started
based on compatible clinical signs and symptoms, initial supportive
laboratory tests, and an assessment of the patient's likelihood of tick
exposure.
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Training
Contacts
Wisconsin
Local Health Departments - Regional offices - Tribal agencies
Diep Hoang Johnson
Vectorborne Disease Epidemiologist
Wisconsin Division of Public Health
Bureau of Communicable Diseases and Emergency Response
(Phone 608-267-0249) (Fax 608-261-4976)
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