Laboratory Diagnosis of Tick-Borne Infections
Part 2
Ehrlichia muris-like Organism
July 2010
Subsequent studies of the Ehrlichia muris-like organism have now revealed infections in at least 5 patients to date, and all of them presented with symptoms similar to human ehrlichiosis due to Ehrlichia chaffeensis such as fever, myalgias, and headache. In addition, we did some experimental testing of ticks that were gathered from the area of the presumed exposures to the EML agent. And we detected EML DNA from a single group of Ixodes scapularis nymphs. At this time, it is unknown if this tick is a vector for disease, and the reservoir host is still unknown. So there is clearly much that we can learn about this new agent of ehrlichiosis in humans in North America.
As far as testing for the EML, some serologic cross-reactivity between the EML and Ehrlichia chaffeensis has been observed at least in one case but the reliability of this cross-reactivity for diagnosis of EML infection is unknown. Therefore, PCR is the test of choice for the newly recognized pathogen at this time.
Ehrlichia muris-like Organism |
Jump to section:
- Introduction
- Presentation Outline
- Tick-Borne Diseases
- Advantages and Limitations of Conventional Tests
- Molecular Diagnostic Methods Potential Advantages
- Molecular Diagnostic Methods Potential Disadvantages
- Treatment and Diagnostic Recommendations
- Case 1
- Diagnostic Workup
- Representative Image Giemsa-stained Peripheral Blood Smear
- Differential Diagnosis
- Which one is Plasmodium falciparum?
- Main Morphologic Features Table
- Classic Maltese Cross
- Extracellular Forms of Babesiosis
- Side-by-Side Comparison
- Further Workup
- Malaria PCR
- Babesia microti PCR
- Advantages/Uses of PCR
- Potential Disadvantages
- Potential Disadvantages
- Case 2
- Lyme Disease: Diagnostic Approach
- Reported Cases of Lyme Disease, 2008
- Serologic Assay: Test of Choice for Diagnosis of Lyme Disease
- Case 2, Further Workup
- Potential Roles for PCR
- Which Specimens Should be Tested by PCR?
- PCR for Detection of Borrelia burgdorferi DNA in Blood
- Case 3
- Live Tick Image
- Tick Image Close Up
- IDSA Guidelines
- IDSA Guidelines, continued
- Testing of Ticks by PCR
- Case 4
- Tick-Borne PCR Panel
- Diagnostic Tests for HME and HGA
- PCR for Diagnosis of Ehrlichiosis/Anaplasmosis
- Ehrlichia and Anaplasma PCR Assay Graph
- Phylogenetic Tree
- Ehrlichia muris-like Organism
- All Patients with EML had Tick Exposure
- Prevention of Tick-Borne Diseases
- Conclusions
- Conclusions, continued
- Questions?
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