New, much faster, more accurate diagnostic for influenza and respiratory syncytial virus

"Instead of relying on insensitive but rapid influenza tests for diagnosis in the clinic, or waiting 24 hours or more for molecular results to come back, we can now provide molecular level sensitivity in less than three hours," says principal investigator Nathan A. Ledeboer of the Medical College of Wisconsin, and Dynacare Laboratories, Milwaukee.

"This will mean that hospitalized patients with influenza and RSV infections will be isolated faster, which will decrease the risk of transmission to other patients in the hospital," says Ledeboer. The faster turnaround also means that "fewer patients will be placed on empiric therapy, which will decrease costs and decrease the risk of an adverse event caused by medication." In the study, the assay, a microarray, was tested on 720 patient samples collected throughout the US.

The new technology, called Respiratory Virus Nucleic Acid Test SP" (RVNATsp), is 98 percent sensitive (meaning that 98 percent of positive results are accurate) and 96 percent specific, meaning that 96 percent of negative results are accurate). By comparison, the conventional alternative, culture, is nearly 100 percent specific, but only 70 percent sensitive.

Influenza virus infects millions annually. It is typically associated with infections of the upper respiratory tract and can cause mild to severe illness. RSV can cause severe symptoms in infants, young children, and immunocompromised individuals, and is the leading cause of hospitalization of children under five years of age. In the most vulnerable individuals, children less than six months old, people with chronic lung disease, and immunocompromised individuals, RSV can migrate from the initial site of infection in the upper airway to the smaller bronchioles of the lower airway, where it can cause life-threatening bronchiolitis or pneumonia.