The story of Thomas Eric Duncan’s experience with Ebola is one that has played out thousands of times in West Africa. The patient fell ill with a fever. Doctors misdiagnosed him. A vial of his blood was shipped to a high-tech laboratory to be tested. By the time virologists confirmed it was Ebola—in this case, four days later—isolation was long overdue.
It’s a sequence of events that captures one of the biggest, and often overlooked obstacles to curbing the spread of the disease in West Africa: inefficient testing.
There is only one approved, working test that can detect whether or not Ebola is present in the blood. One. The powerful technology required is slow, complicated, and requires both a laboratory and equipment. It is not that more-efficient tests do not exist; it’s that we don’t yet have the permission needed to use them.
As Ebola cases in West Africa surpassed 6,000 last week, Dr. Bob Garry, a scientist at Tulane University, is working harder than ever to get one possible solution—a rapid diagnostic test—approved. Until that happens do, testing will remain the epidemic’s secret ally.
The vial of blood taken from Duncan in Dallas was sent to the Centers for Disease Control and Prevention’s Atlanta lab, where a single test was performed. It’s the same one used by doctors in West Africa, or anywhere in the world. The test, called polymerase chain reaction (PCR), uses a method to amplify the DNA to a point where the virus can actually be detected. But the technology, while powerful, is cumbersome and takes anywhere from 12 hours to four days to yield a result.
This isn’t the best test for this epidemic, but it’s the only one.
Garry says the biggest problem with this test is in its high-tech, time-consuming method.
For example, a vial of the patient’s blood is transported to one of the few laboratories in West Africa with the suitcase-size PCR equipment needed to test for the virus. These facilities, among other more sophisticated equipment, require central electricity. In many parts of West Africa, this is hard to find. The test can take anywhere from one day to four. Factoring in travel, an answer to a sick patient’s question could be as much as a week away.
At the outset of this process, the patient is told to remain at the treatment center until a diagnosis can be made. But by the time the test results come back, the vast majority are gone. Some have fled the hospital in fear. Some have gone into hiding. Some have gone home to die. All of those who are positive have now needlessly spread the virus to countless others.
It’s the breakdown in care caused by delay that Garry and his team are hoping to fix. The scientists began working in West Africa roughly 10 years ago on another fever called Lassa. Over the course of a few years, they developed a rapid diagnostic test that allowed doctors to give patients a diagnosis on the spot. When the first cases of Ebola began popping up in West Africa, Garry and his team began “fortifying” existing labs they had in the area. In the creation of the Lassa fever test strips, they had also made a similar, but separate, Ebola test. But without any presence of Ebola in the region until this year, they were unable to test them until now.
The value of the rapid diagnostic test lies in its simplicity. It consists of a small white lancet, which requires just a small drop of blood. In 15 minutes or less, a positive or negative line will appear on the test, indicating Ebola positive or negative. "They work like pregnancy tests except its blood," says Garry.
“What our tests would permit one to do is to basically see if a person has Ebola on the spot,” Garry tells me. “They are not perhaps as sensitive as a PCR. That’s a very sophisticated test, but they don’t really have to be. What we’re most interested in doing is coming out with a test that could detect when someone is infectious, immediately.”
Taken into a clinical setting in West Africa, the test would allow physicians to immediately determine the condition of their patient, improving both the health of that individual and the safety of those around them. By immediately isolating patients that test positive, Liberia, Guinea, and Sierra Leone could prevent infected patients from going back to their village and spreading the virus further.
Dr. Alan Wu, a chemistry lab director at San Francisco General and professor at lab medicine at University of California SF, said he believes the rapid diagnostic testing is necessary in the U.S. as well. At his hospital in San Francisco, he’s received CDC training in preparation for an outbreak. But if a case comes in that he suspects is Ebola, he won’t be able to test it himself. Wu has been instructed to send the vial to the CDC’s headquarters in Atlanta—one of 12 labs in the nation (according to the CDC) capable of performing the test. “Not everyone can do molecular tests, whereas anyone can do a finger stick,” he says. “This is not going to go away. This is not a handful of patients. It’s going to have an impact on Americans as other people interact with people from that part of Africa, so we need products and we need a nimble system that will allow products to be available in advance.”
So if the test is so promising, why aren’t we already using it? “We have to prove that it works,” says Garry. “The timing is what’s holding us up.” In July at the American Association for Clinical Chemistry (AACC)’s Annual Meeting and Clinical Lab Expo, Corgenix (the company behind the rapid test) and the Viral Hemorrhagic Fever Consortium were awarded $2.9 million in grant money by the National Institutes of Health to continue work on the development of the Ebola test kit. [See our post on the Corgenix-Tulane project for more information.]
Three months later, Garry and his team are prepped and ready to have hundreds of thousands, “even millions,” of the rapid tests ready to send to West Africa. But without 100 percent proof that it works, they’re at a standstill. With the news of an American being diagnosed with Ebola on U.S. soil, Garry hopes the process may be sped along. Not only so the test can be used in the States—but on planes.
With Garry and Corgenix’s previous rapid tests for Lassa used extensively—and successfully—in Sierra Leone and elsewhere, the evidence is even more compelling that their Ebola test will get approval. In the eyes of Wu, the test should already be out in the field, despite a lack of 100 percent proof. “If you have a positive, even if it’s a false positive, you’re erring on the side of caution. That is good.”
But not all physicians see rapid diagnostic tests as the answer. Kent Sepkowitz, an infectious disease specialist from New York (and contributor to The Daily Beast) said he thinks the technology is simply coming too late. “It will be great when the Ebola outbreak starts in 2016, or whenever the next one is. Would have nipped that in the bud.” says Sepkowitz. “But I think they need gowns and hospital rooms much more than rapid tests.”
While the rapid diagnostic test could help this epidemic, it’s by no means a longterm solution West Africa, where thousands die of other viruses each year. "We will get to a point where Ebola is not the only thing people are thinking about,” says Doug Simpson, President and CEO of Corgenix. In effort to address the larger issue, Simpson’s company has teamed up with Nanomix, a a leading nanotechnology company focused on the development of next generation Point of Care diagnostic tests. The joint venture entails Corgenix migrating the rapid diagnostic tests into a handheld device designed by Nanomix. In a matter of minutes, using multiplex detection on a drop of blood, the handheld device can distinguish between at least five different common disease ranging from Malaria to Lassa Fever. "The longterm answer is you have to be able to differentiate between the diseases,” says Simpson. “I think that’s the answer."
As the epidemic rages on, Garry is working tirelessly to get the test through the U.S.’s clunky approval process. The delay, he says, is not for lack of backing. “At the very highest level of government they know about it,” says Garry. “We’re trying to work as quickly as we can.” While he stresses that the test isn’t scientifically smarter than the existing PCR, he’s aware of its power to potentially change the tide of the epidemic. “If you could quarantine people on the spot… it would make a big difference in trying to shut this thing down.”
The response to the Ebola epidemic in West Africa has surged in the past few weeks, delivering more money, supplies, and doctors. As the region is flooded with goods, Garry and his team are stripping the virus testing process bare. It’s not another Ebola test that the world needs, but a simpler one.
Source: The Daily Beast and rapidmicromethods.com