Ebola laboratory tests
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Michael Maddaleni, B.S.
Overview
Ebola would be categorized as a viral hemorrhagic fever. Antigen-capture enzyme-linked immunosorbent assay (ELISA) testing, IgM ELISA, polymerase chain reaction (PCR), and virus isolation can be used to diagnose a case of Ebola HF within a few days of the onset of symptoms. Persons tested later in the course of the disease or after recovery can be tested for IgM and IgG antibodies; the disease can also be diagnosed retrospectively in deceased patients by using immunohistochemistry testing, virus isolation, or PCR.[1]
Laboratory Findings
There are no specific laboratory findings of Ebola virus disease, the following table shows some nonspecific usually found:[2]
| Test | Findings |
|---|---|
| White blood cells count | Leucopenia (1000 cells/μL) Lymphopenia Neutrophilia |
| Blood smear | Left shift Atypical lymphocytes |
| Liver function tests | Raised aspartate aminotransferase Raised alanine aminotransferase Extended prothrombin time Extended partial thromboplastin time |
| Proteins | Hyperproteinemia |
| Urinalysis | Proteinuria |
Diagnostic tests
| Diagnostic test | Samples required | Preparation & Storage | Shipping | Viruses to be confirmed |
|---|---|---|---|---|
| ELISA (serology) detects: | Whole blood serum or plasma†
Acute and convalescent†† |
Freeze or refrigerate
(as cold as possible) |
Frozen on dry ice or ice packs or both†††† | Ebola Lassa CCHF Rift Valley Marburg Yellow fever |
| PCR detects: | Whole blood or clot†† | Refrigerate or freeze
Freeze |
Frozen on dry ice or ice packs or both†††† | Ebola Lassa CCHF Rift Valley Marburg Yellow fever |
| Immunohisto-chemestry (liver) detects: | Liver biopsy from fatal cases | Fix formalin (can be stored up to 6 weeks) | Room temperature (do not freeze) | Ebola Lassa CCHF Rift Valley Marburg Yellow fever |
| Immunohisto-chemestry (skin) detects: | Skin biopsy from fatal cases (any site) | Fix in formalin (can be stored up to 6 weeks) | Room temperature (do not freeze) | Ebola Lassa |
| Immunohisto-chemestry (other tissues) detects: | Tissue biopsy from fatal cases | Fix in formalin (can be stored up to 6 weeks) | Room temperature (do not freeze) | Ebola Lassa CCHF Rift Valley Marburg Yellow fever |
† Whole blood can be used for enzyme-linked immunosorbent assay (ELISA) and may be frozen. Do not centrifuge suspected VHF specimens because this increases risk to the lab worker. If serum specimens have already been prepared these can be used. Place specimens in plastic tubes for shipping and storage and be sure that the tubes are sealed and properly labeled.
†† Collect acute-phase specimen when patient is admitted to hospital or diagnosed as suspected case and collect convalescent-phase specimen at death or when discharged from the hospital.
††† whole blood or tissue is preferred, although serum or plasma may provide results.
†††† Use both ice packs and dry ice to provide best results. If dry ice or ice packs are not available, sample may be shipped at room temperature and still provide valid results in most cases.
Ebola virus can be detected in fatal cases from a skin specimen using immunohistochemistry or RT-PCR tests developed by the Centers for Disease Control and Prevention (CDC). The skin specimen is fixed in formalin or chaotrope which kills the virus. The specimen is no longer infectious once it is placed in formalin or chaotrope and the outside of the vial has been decontaminated. This vial can be shipped by mail or hand carried to the lab without risk. Results are available within a week after the specimen arrives at the CDC.
References
- ↑ "Ebola Hemorrhagic Fever Information Packet" (PDF).
- ↑ Feldmann H, Geisbert TW (2011). "Ebola haemorrhagic fever". Lancet. 377 (9768): 849–62. doi:10.1016/S0140-6736(10)60667-8. PMC 3406178. PMID 21084112.