During the pilot study, it produced no false negatives, fewer false positive, and fewer inconclusive results. The disease is nearly always fatal once clinical signs of infection appear and supportive treatment is the only option.
Currently, the "gold standard" for confirming rabies infection in animals is a direct fluorescent antibody (DFA) assay that, the CDC noted, requires "laboratory workers with special skills, extensive training, and a specific type of microscope".
"If we can eliminate the fear for people and get information as quickly as possible, thats really the end all, be all", Cheryl Gross from the Central Animal Hospital said. Currently, testing facilities in many countries in Africa and Asia most affected by rabies are not able to easily rule out the disease in animals that have bitten someone.
In a press release announcing the results, the CDC said availability of such a test could transform how suspected rabies exposure in humans is treated, both in the USA and around the world.
In the recent study, staff at 14 labs worldwide assessed almost 3,000 animal brain samples from the Americas, Europe, Africa, and Asia, of which more than 1,000 were known to be infected with rabies virus.
LN34 correctly identified all DFA-positive samples as positive.
In addition, it produced definitive findings for 80 samples which were inconclusive or untestable by the DFA test - and 29 of those were positive for rabies.
All samples testing positive with DFA were also positive with LN34, according to the CDC press release, which did not indicate the false-positive rate (those data were to be in a PLOS One paper to be released later Wednesday) but said it was lower than with DFA. Only one sample was indeterminate using both tests. Most commonly spread through the bite of an infected animal, according to the CDC, the rabies virus can also spread through scratches, abrasions, open wounds, or mucous membranes contaminated with saliva or other potentially infectious material (such as brain tissue) from a rabid animal.
Most mammals can contract rabies, with bats a known vector or carrier of the disease - although the illness has been eliminted in the UK. Having a quick, easy-to-run and accurate test to tell if an animal that bit someone is rabid could help doctors decide whether someone needs preventive treatment. This study is the largest ever to validate usage of this type of test (a real-time RT-PCR) to diagnose rabies in animals.
The test, done on suspect animals, can be run on platforms already widely used to screen for the flu, tuberculosis and HIV. The individual cost of the rabies vaccine for humans in the United States is over $3000. Experts estimate that rabies testing, prevention, and control cost $245 to $510 million annually in the United States.
The United States may also benefit from testing advantages offered by the LN34.