Mayo Test Catalog, (Sorted By Test Name) - Mayo Medical ...

FELAS
90158
detection of antibodies to Ehrlichia chaffeensis. In 2009, Mayo Medical Laboratories detected a new
species of Ehrlichia DNA in 4 patients (3 from Wisconsin, 1 from Minnesota) using PCR. The unique
nucleotide sequence is similar to Ehrlichia muris, a species not previously identified in North America.
The Ehrlichia muris-like (EML) organism has since been found in some Ixodes scapularis ticks in
Wisconsin, although it is not known whether this tick serves as a vector. Infective forms of these
organisms are injected during tick bites and the organisms enter the vascular system where they infect
leukocytes. They are sequestered in host-cell membrane-limited parasitophorous vacuoles known as
morulae. Asexual reproduction occurs in leukocytes where daughter cells are formed and liberated upon
rupture of the leukocytes. Most cases of ehrlichiosis are probably subclinical or mild, but the infection can
be severe and life-threatening with a 2% to 3% mortality rate. Fever, fatigue, malaise, headache, and other
"flu-like" symptoms, including myalgias, arthralgias, and nausea, occur most commonly. Central nervous
system involvement can result in seizures and coma. The 4 patients infected with the EML organism
presented with fever, myalgias and leukopenia. Diagnosis of ehrlichiosis may be difficult since the
patient's clinical course is often mild and nonspecific. This symptom complex is easily confused with
other illnesses such as influenza, or other tick-borne zoonoses such as Lyme disease, babesiosis, and
Rocky Mountain spotted fever. Clues to the diagnosis of ehrlichiosis in an acutely febrile patient after tick
exposure include laboratory findings of leukopenia or thrombocytopenia and elevated serum
aminotransferase levels. However, while these abnormal laboratory findings are frequently seen, they are
not specific. Rarely, intragranulocytic or monocytic morulae may be observed on peripheral blood smear,
but this is not a reliable means of diagnosing cases of human ehrlichiosis/anaplasmosis. Definitive
diagnosis is usually accomplished through PCR and/or serology methods. PCR techniques allow direct
detection of pathogen-specific DNA from patients' whole blood during the acute phase of disease. This is
currently the test of choice for the newly described EML organism. Serologic testing is usually done only
for confirmatory purposes, by demonstrating a 4-fold rise or fall in specific antibody titers to Ehrlichia
species or Anaplasma antigens. There is not currently a specific serologic test for the EML organism, and
cross-reactivity with the other Ehrlichia species by serology may be unreliable. It is important to note that
concurrent infection with Anaplasma phagocytophilum, Borrelia burgdorferi, and Babesia microti is not
uncommon as these organisms share the same Ixodes tick vector, and additional testing for these
pathogens may be indicated.
Useful For: Evaluating patients suspected of human granulocytic anaplasmosis or human monocytic
ehrlichiosis
Interpretation: Positive results indicate presence of specific DNA from Ehrlichia chaffeensis,
Ehrlichia ewingii, Ehrlichia muris-like, or Anaplasma phagocytophilum and support the diagnosis of
ehrlichiosis or anaplasmosis. Negative results indicate absence of detectable DNA from any of these 4
pathogens in specimens, but it does not exclude the presence of the organism or active/recent disease.
Since DNA of Ehrlichia ewingii is indistinguishable from that of Ehrlichia canis by this rapid PCR
assay, a positive result for Ehrlichia ewingii/Ehrlichia canis indicates the presence of DNA from either
of these 2 organisms.
Reference Values:
Negative
Clinical References: 1. Bakken JS, Dunler JS: Human granulocytic ehrlichiosis. Clin Infect Dis
2000 Aug;31(2):554-560 2. Dunler JS, Bakken JS: Human ehrlichioses: newly recognized infections
transmitted by ticks. Ann Rev Med 1998;49:201-213 3. Krause PJ, McKay K, Thompson CA, et al:
Disease-specific diagnosis of coinfecting tickborne zoonoses: babesiosis, human granulocytic
ehrlichiosis, and Lyme disease. Clin Infect Dis 1999 May 1;34(9):1184-1191 4. McQuiston JH,
Paddock CD, Holman RC, Childs JE: The human ehrlichioses in the United States. Emerging Infect Dis
1999 Sept-Oct;5(5):635-642
Elastase, Pancreatic, Serum
Clinical Information: Serum Elastase, also called Pancreatopeptidase, is a protease present in
pancreatic secretion with the unique ability to rapidly hydrolyze elastin. Elastin is a fibrillar protein
found in connective tissue. Elastin forms the elastic fibers found mostly in lungs and skin. Elastase is
able to hydrolyze denatured hemoglobin, casein, fibrin, albumin and denatured but not native collagen.
Current as of January 3, 2013 2:22 pm CST 800-533-1710 or 507-266-5700 or MayoMedicalLaboratories.com Page 661