"Home brew" polymerase tests lead to pseudo-epidemics

With so many biotech start-ups working on reliable, near-instantaneous sensors capable of detecting pandemic diseases, it is worth noting what happens when such tests are performed under less-than-deal conditions. Many hospitals, it seems, have developed their own “home brew” methods, preferring to test on molecules rather than wait weeks for the results of a culture test to tell them if they have an epidemic on their hands. That is smart thinking — at least until the market for commercial devices matures — but it can lead to mistakes. Such was the outcome of what was supposed to be a whooping cough outbreak at Dartmouth-Hitchcock Medical Center. Eight months after a coordinated pandemic response was launched, it turned out the polymerase assay used was flawed. The effected doctors and patients merely had the flu.

The problem, epidemiologists and infectious disease specialists say, was that they “placed too much faith in a quick and highly sensitive molecular test that led them astray.” And they were not the only ones to fall into this trap. Pseudo-epidemics happen all the time, one recent example being a similar whooping cough scare at Children’s Hospital in Boston last fall that involved 36 adults and 2 children. “It’s a problem; we know it’s a problem,” said one involved doctor. “My guess is that what happened at Dartmouth is going to become more common.” One reason for pessimism is that home brew tests have unknown error rates, yet their high sensitivity makes false positives extremely likely. “You’re in a little bit of no man’s land,” with the new molecular tests, said Dr. Mark Perkins. “All bets are off on exact performance.” In addition, no best practices have emerged. According to experts, there are more than 100 polymerase chain reaction protocols in use nationwide.

-read more in Gina Kolata’s New York Times report