Countries all over the world now recognize the Ebola virus disease as a threat. The United States is helping to fight the spread of the disease in West Africa and also providing care for those infected, including patients brought to the United States for treatment. The federal government has asked clinical laboratories to take stock of their preparedness to contain and care for patients suspected of having EVD.
In this context, a group of researchers from the University of Nebraska Medical Center, Omaha studied the safety considerations in laboratory testing of specimens suspected or known to contain Ebola virus. The study, published in www.aapc.org and to appear in January 2015 issue of the American Journal of Clinical Pathology 2015, assesses the preparedness of core laboratories that perform chemistry and hematologic testing to safely handle specimens suspected of containing or known to contain Ebola virus. The researchers hold that their findings and recommendations may have general applicability to tertiary medical centers that typically use closed-system automated laboratory equipment and where a Biosafety level 3 (BSL-3) facility is available in which appropriate BSL-3 practices are followed.
This evaluation is based on the interim guideline and supplemental document provided by the Centers for Disease Control and Prevention (CDC) for how US laboratories could safely manage specimens from persons suspected of having EVD. The CDC recommends that each laboratory conduct “risk assessments to determine the potential for sprays, splashes, or aerosols generated from laboratory procedures when handling these specimens and to adjust work practices, safety equipment controls, and personal protective equipment (PPE) requirements as needed to provide a safe environment in the laboratory”.
The researchers assessed adherence to Biosafety level 3 practices in core laboratories, the potential for microdroplet or aerosol generation during testing of blood specimens, and both essential and supplemental tests that could be done safely to manage patients infected with Ebola virus. Here is a brief summary of their findings:
- It was found that core laboratories where chemistry and hematologic testing takes place are not equipped to handle specimens from persons under investigation (PUIs) for EVD or known to have EVD. Biosafety level 3 (BSL-3) include measures to deal with indigenous or exotic agents that may cause serious or potentially lethal disease through the inhalation route of exposure, and include processing within a biosafety cabinet, centrifugation using safety cups or sealed rotors, and enhanced PPE to include respiratory protection.
- The study reports that practices such as the use of open tubes without the availability of a biosafety cabinet and centrifugation of specimens without safety cups or sealed rotors core are common in core laboratories. BSL-3 practices were found to be generally available only to clinical microbiology laboratories and specifically for testing of specimens that contain agents that may cause tuberculosis or endemic fungi.
- Assessment of the potential for microdroplet or aerosol generation which posed a threat to laboratory personnel indicated that only closed manual or automated chemistry and hematology analyzers were safe for the testing of blood containing specimens with potential Ebola virus present outside the BSL-3 containment laboratory. The researchers came to this conclusion based on the fact that automated instruments including centrifuges can generate microdroplets of blood and a droplet of blood was sufficient to cause Ebola infection, posing a potential risk for laboratorians.
- They also determined a list of both the essential and supplemental tests that could be done safely to manage patients infected with Ebola virus along with the laboratory locations where the tests were performed. In cases where testing was considered not safe such as fibrinogen levels, procalcitonin levels, and cross-matching of blood, the study recommends that consultation would be needed between the requesting physicians and the laboratory personnel to determine alternative tests that could be used.
- As maintaining cardiopulmonary function and electrolyte balance is critical in caring for patients with EVD, an expanded menu of laboratory tests is considered essential for optimal patient management.
The researchers conclude that with the right blend of capabilities, laboratories could provide for the initial processing of specimens from PUI for EVD with centrifugation followed by testing in locations that are suitable for either point-of-care assays or closed automated platforms.