THE CANADIAN PRESS -- TORONTO - Breath tests are commonly used to detect blood alcohol levels and monitor asthma, and now a similar test could possibly help identify people infected with the H1N1 flu virus, a new study suggests.
A breath test measuring the immune response to the H1N1 flu virus could help doctors avoid doling out unnecessary vaccinations to people already infected with the virus, and prioritize those most in need of them, researchers say.
The study was conducted by the Cleveland Clinic in Ohio and New Zealand-based Syft Technologies and published Friday in the Journal of Breath Research.
Study co-author Dr. Raed Dweik said when the H1N1 epidemic happened a couple of years ago physicians were faced with a dilemma related to patient treatment.
"We see these patients coming in with a fever and maybe flu-like symptoms but 'Do they have H1N1 or do they not?'" Dweik, a professor of medicine and director of the pulmonary vascular program at the Cleveland Clinic, said in an interview.
"You need to know quickly and treat them if they have that strain, and if they don't, you probably can treat them differently."
Researchers enrolled 11 individuals in the small study. A live attenuated H1N1 vaccine -- which mimics the natural infection -- was administered via a nasal spray.
Participants were given breath tests prior to the vaccination and then again each day for seven subsequent days.
Samples of exhaled nitric oxide were provided by six participants prior to vaccination. Nitric oxide is a test approved by the U.S.
Food and Drug Administration for monitoring inflammation and asthma, said Dweik. Production of exhaled nitric oxide, or NO, has also been linked to influenza and viral infection.
"We all have nitric oxide in our breath because our lungs make it, but with different levels," said Dweik. "If you have an infection or an inflammation or if you have asthma, it goes up."
Researchers found that NO levels peaked on the third day following vaccination. Analysis of other compounds in the breath during that timeframe found that the most change occurred on that same day.
"Something was changing every day in the breath ... but Day 3 is when most of the changes happened," Dweik said.
"It makes the most sense medically that this is the time where our bodies really have the most significant response, or maybe the viral load is the highest due to the infection."
Dweik cautions that while the work is "rather preliminary," he sees it as proof of the concept that breath can be used to monitor the vaccination and, it is hoped, the infection.
The next step is to find out what the compounds are that change in the breath and how they are linked to the vaccine or disease, he said.
"There are several possibilities," Dweik said. "One, that they are a signature of the virus itself, that the virus might be produced in some of these compounds and that's why we're getting them in the breath.
"It could be that it's our immune response to the virus, our body's response to the virus generates these compounds, or a combination of the two."
Dr. Danuta Skowronski of the BC Centre for Disease Control, echoes researchers' cautions that the results are preliminary, adding that the sample itself is too small to draw definitive conclusions.
"They're looking at just six people pre- and post-immunization. That's too small to say anything conclusive," said Skowronski, the epidemiology lead for influenza and emerging respiratory pathogens.
"They don't include a comparison group to know how do those levels that they're looking at in the breath test ... normally fluctuate with time in a given week, and it's too small for them to take into account other possible influences like exercise or stress or age or diet."
Skowronski said the researchers should be applauded for trying to examine other correlates of protection against the flu, but that it's way too preliminary for broad application of their findings at this time.
"I think this study should be considered hypothesis-generating, preliminary and thought-provoking," she said.
"It definitely warrants further study, but we can't consider this as the springboard for breath-testing people for influenza protection. That's going too far."