UNC Researchers Develop New Test for Detecting Ebola
February 22, 2017
Institute for Global Health and Infectious Diseases
Amy James Loftis is part of a University of North Carolina at Chapel Hill study team that sought to find a fast, readily-available way to detect Ebola in semen. Working with colleagues in Liberia, she recently proved that the Cepheid Xpert Ebola assay test can reliably detect traces of the Ebola virus in semen. While a test for measuring Ebola in the blood exists, this is the first validated test for Ebola in semen. The study’s results were published in the Journal of Infectious Diseases.
“Survivors of this outbreak want to know, ‘am I fully cleared of Ebola?’” says Loftis, UNC’s Division of Infectious Diseases Clinical Trials Unit Lab Manager. “The answer is yes in the blood, but maybe not in genital secretions, so we needed to develop an accurate test, understand the limits of this test and then provide guidance based on those limits.”
Loftis and colleagues collected samples of blood and semen from uninfected individuals at the Phebe Hospital in Bong County, Liberia. The team then added inactivated Ebola virus to prepare 300 samples at various viral concentrations. Using a specimen preparation protocol provided by the NIH, she and colleagues from UNC and Phebe Hospital rigorously evaluated the test in Liberia to determine the lower limit of detection and reliability. The Cepheid Xpert Ebola assay produced a lower limit of detection of 1,000 copies per milliliter in semen and 275 copies per milliliter in blood.
Liberia is home to an unprecedented number of Ebola survivors, who Loftis says are eager to be tested to confirm whether or not they are still infected. The World Health Organization advises men who tested positive for Ebola to either abstain from sex or use condoms for one year after the onset of symptoms or until their semen has tested negative for the virus twice.
“These results validated the Cepheid Xpert Ebola assay for detecting the virus in semen and showed that you need an even more sensitive test for genital secretions than for blood,” Loftis says. “This is similar to what we’ve found in our HIV research in that the limit of detection in genital secretions is higher than in blood.” However, many questions remain including whether or not these samples contain infectious virus or just viral RNA; this work is ongoing.
Loftis and her research counterparts are close to completing work to use this test for detecting the virus in female genital secretions.
“This most recent Ebola outbreak is unique in that it left a lot of survivors and we do not know what that means. What other places could the virus be hiding in the body? Could it resurface?” Loftis says. “We will keep following this cohort of survivors and continue our efforts to push the diagnostics field forward. At the end of the day, it’s important to remember that a quality test yields sound public health guidelines.”