For health workers to currently diagnose the presence of Ebola virus, a full vial of venous blood must be shipped to a laboratory with a high level of both biosafety and staff expertise.
For health workers to currently diagnose the presence of Ebola virus, a full vial of venous blood must be shipped to a laboratory with a high level of both biosafety and staff expertise. There, the blood sample is tested using a method called real-time reverse transcription polymerase chain reaction (RT-PCR).
However, RT-PCR is a slow and complex test that comes with attached risks for the health care workers responsible for the collection, transportation and testing of the blood. The complexity and slow turnaround for this diagnostic have been blamed for delaying success in containing the epidemic.
Dr. Nira Pollock, senior author and associate medical director of the Infectious Diseases Diagnostic Laboratory at Boston Children's Hospital, MA, says that because the laboratory results from the test can take days to return:
"Delays like this result not only in the failure to diagnose and treat Ebola-infected patients, but also in individuals without Ebola being admitted to holding units where they may be subsequently infected with the virus."
By contrast, Dr. Pollock says that the new ReEBOV Antigen Rapid Test is capable of detecting Ebola virus in just a drop of blood tested at a bedside.
New test and benchmark test put head-to-head
The accuracy of the new test was compared in the study with the benchmark RT-PCR test. The study used both tests to diagnose 106 suspected Ebola patients who were admitted to two treatment centers in Sierra Leone during February 2015. Both tests were also performed on 284 samples in the laboratory.
The new test confirmed all of the positive cases that were diagnosed in both the point-of-care patients and laboratory blood samples using the RT-PCR test.
Dr. Jana Broadhurst, from Partners In Health, the nongovernmental, US-based organization who supported the treatment centers, says:
"This test could have an immediate impact on patient care and infection control by reliably detecting patients well into their illness who are likely to be highly infectious. Earlier test results would improve triage of patients, enabling staff to focus on those most likely to have Ebola, and reducing the opportunity for infection of non-Ebola 'suspects.' Although the RDT requires refrigeration, this is already available in many health centers in endemic areas, particularly those that store vaccines and other medical products."
Dr. Nahid Bhadelia, from Boston University School of Medicine and Boston Medical Center, MA, writes in a linked comment that the study validates the accuracy of the ReEBOV test. "Earlier test results would improve triage of patients," she writes, "enabling staff to focus on those most likely to have Ebola, and reducing the opportunity for infection of non-Ebola 'suspects.'"
Earlier this week, we looked at a report published in The Lancet Infectious Diseases that suggested confusion between malaria and Ebola symptoms has contributed to around 74,000 fewer reported cases of malaria than expected in Guinea. The report authors believe this level of misdiagnosis will cause the number of deaths from malaria in the country this year to exceed the total number of Ebola deaths.