Don't hold your breath: should another H1N1 virus outbreak raise global concern as it did in 2009, merely exhaling could reduce pandemic alarm and identify who needs help.
Quickly spotting people infected with H1N1 (aka swine flu) could help health care officials prevent vaccine shortages by better targeting who receives the limited supply of medicine. Additionally, sorting the healthy from those who are already infected with virus is a vital step in preventing a pandemic, and screening airline passengers for the virus could help stop the spread of a deadly flu before it circles the globe.
"More important than the cost of the vaccine is, if there is a test, a way to test people. If there is a way to find who is infected, that will allow you to direct the vaccine to where it is needed most, not to people who don’t need it," said researcher Raed Dweik, a doctor at the Cleveland Clinic and co-developer of the flu breathalyzer.
Currently, only a time-consuming nasal swab can tell doctors whether a patient with a fever has H1N1 or some other virus, Dweik said. Blood tests are even more invasive, and also require a lab trip. In a weeklong pilot study, the scientists discovered the first evidence that they may be able to rely on breath tests to make that diagnosis in real time.
Out of the 12 compounds analyzed in the breath content of health care workers who had been given the vaccine, only one displayed a peak on the third day of exposure. Previous studies have shown that swine flu symptoms and severity surges to its highest point on that day, suggesting that researchers had witnessed an immune response rather than a residue from the vaccine. Parsing out the false positives and false negatives of the breath test will take time, but the researchers think they're already on the right track.
"In my mind, if you have a signature from the vaccine, I think the disease will have an even easier time to be detected," Dweik said.
Called isoprene, the detected molecule was not initially of much interest compared to the seemingly more relevant nitric oxide (NO), a compound previously linked to influenza and virus infection in general. But the timing of its elevated levels was significant to researchers knowledgeable about the H1N1 life cycle.
If miniaturized, and incorporated into handheld devices, the sensors used in the breathalyzer test could easily perform fast, noninvasive testing of swine flu. More research is needed to determine false positive/negative rates and to distinguish those who have received the vaccine from those who have the full-blown virus. Outside of preserving limited stockpiles, this tool would also have the potential to help enforce quarantine like the heat sensors used in airports in Japan, which help identify sick passengers.
In the future, exhaled breath analysis could revolutionize other forms of medical testing, Dweik said. Even conditions separate from the lungs such as heart failure and liver disease show their own peaks in gaseous molecules.
"Our goal is to build something the size of a cellphone or key chain that you can blow into and then detect whatever disease you are looking for," Dweik said.
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