Virus World

In an analysis of the real-world impact of a pioneering test called metagenomic next-generation sequencing (mNGS), developed by scientists to diagnose patients with mysterious inflammatory neurological conditions, the technique was shown to identify infections better than any standard clinical method.

 

"The infectious cause of half the cases of meningitis and encephalitis go undiagnosed in hospitals around the country, and these severely ill patients are in dire need of a better testing tool," said Charles Chiu, MD, PhD, professor of laboratory medicine and medicine at UCSF and senior author of the new study. Unlike conventional testing, which is often driven by doctors' hunches, the mNGS test offers an unbiased approach that can detect nearly all possible pathogens -- bacteria, viruses, fungi and parasites -- present in patients' spinal fluid, giving doctors clear direction for treatment. 

The study, published June 13, 2019 in the New England Journal of Medicine, was set up to enroll only the most challenging cases. To qualify, a patient had to be hospitalized with an acute neurological illness with no conclusive diagnosis. The study included 204 pediatric and adult patients, mostly from California, who had meningitis (inflammation of the lining surrounding the brain), encephalitis (inflammation of the brain itself) or myelitis (inflammation of the spinal cord).

 

The test found many of the same infections identified by conventional laboratory testing methods, which generally look for pathogens one at a time, and require that doctors know what they are looking for to be successful. But it also found 13 infections that were missed by all conventional tests, such as a case of infection by St. Louis encephalitis virus, which had not been seen in California since 1986. And in more than half of those cases, the mNGS diagnosis was indispensable in guiding the treatment of these patients. In a case of hepatitis E virus infection that had been missed by conventional testing, the successful mNGS diagnosis likely spared the patient from having to undergo a liver transplant.