A new method developed by California researchers could transform how Ebola is identified, letting medics diagnose the disease in the field instead of sending samples to labs. That could speed containment of the virus in West Africa, which has seen one of the decade’s worst disease epidemics because of the difficulty in diagnosing Ebola.
The system relies on two chips: a “microfluidic” chip, used to deposit and prepare the sample, and an “optofluidic” chip, which can detect individual molecules containing the virus. Preliminary tests show the method to be as effective as a conventional lab test, according to a paper published Friday in Scientific Reports.
Since Ebola’s outbreak in Guinea in 2013, the disease has killed more than 11,000 people across West Africa, with new cases still occurring in Guinea and Sierra Leone. The disease is hard to stop; symptoms often don’t appear for many days, and it can take even longer for diagnostic tests to confirm the virus.
“Diagnostic capacity is especially important, as the early symptoms of Ebola virus disease mimic those of many other diseases commonly seen in this region, including malaria, typhoid fever, and Lassa fever,” the World Health Organization said in a situation assessment following the initial outbreak of the disease.
Ebola diagnosis has typically relied on a test known as PCR (polymerase chain reaction), which involves virus samples being sent to a lab so genetic material can be studied. It’s a complicated process because the method relies on examining DNA molecules. Unfortunately, the Ebola virus is not made up of DNA, but of RNA. While RNA is similar, it has a different structure and serves another purpose in the body. DNA copies of the RNA must be made before testing can begin.
“Compared to our system, PCR detection is more complex and requires a laboratory setting,” said the paper’s senior author, Holger Schmidt, a professor of optoelectronics at the University of California, Santa Cruz. “We’re detecting the nucleic acids directly, and we achieve a comparable limit of detection to PCR.”
The method described by the researchers from Santa Cruz and UC Berkeley is relatively simple, making it a “user-friendly technology for point-of-use diagnosis, especially in resource-limited settings,” the researchers wrote in the paper. The system involves examining single molecules one at a time as they pass through a tiny, fluid-filled channel on a chip.
Initial tests have been carried out on viral samples, but the next step involves tests with raw blood samples, which will need to take place in a facility with a higher biosafety level.
Schmidt said his team is working on ways to use the same system to detect other diseases.