Is it within the technological capability of current bio-medical science to have someone walk through a detector, and have a detection response more of less instanteously, indicating if they are shedding (ie contagious with) a particular virus? Obviously the “detectable” virus needs to be one that is airborne in this case.
How about it?
As a follow-up question, would this device break were Paris Hilton to walk through it?
A company in St. Paul, Minnesota, Thermal Systems Incorporated (TSI), makes a product called an Aerodynamic Particle Sizer that measures the velocity of airborn particles as they are accelerated through a series of jets. They were selling this for, among other things, rapid detection of aerosolized germ warfare agents on the battle lines in the Iraq War. I mean, Bush’s Iraq War. I mean, the first Bush’s Iraq War. Jesus, will they never let up? Well, you get the idea…
You could have something that detects viral DNA/RNA or proteins but this would probably take a few hours to run. Maybe you could use some sort of fluorescence, but I can’t think of how.
What about a microarray coated w/small molecules that will bind to viral coat proteins? It would be expensive, but I think it could be done.
IMHO, this would probably be impractical for real-time use for several reasons:
Virions are rarely “shed” like microscopic dandruff in appreciable amounts. The skin is not a major means of exit and spread for viruses (except for mucosal surfaces, and the hands, which often acquire virons from touching your face, etc.).
Virions have a much smaller (as little as one-millionth the volume) infectious unit than bacterial diseases (such as the ones proposed above) This means much less than less than picogram (a millionth of a millionth of a gram) quanities of whatever you’re testing for. Chemical tests can only detect a specific part of a virus – say a specific part of a coat protein or a specific small sequence in the DNA. These are only a tiny fraction of the already tiny virion.
When virions are shed, they are rarely free-floating isolated particles (which would actually make detecting them easier, due to their small size). They would be on -or locked in- dried droplets from respiratory secretions, dislodged skin cells, etc. An actual viron, if present, would be a small fraction of these particles
If I wanted to establish, say, an pre-boarding airport screening for passengers who are actively contagious with viral diseases, I would conduct it on wipes of their hands, noses, etc., preferably of symptomatic individuals I think most people realize would entail a substantial delay, even at a hospital. We only have “instant screening tests” for a handful of diseases, like strep throat, and even those have a limited sensitivity and specificity for actual contagious disease (e.g. 5-30% of normal healthy people routinely carry meningococcus, but do not have or spread infectious meningitis.)
A single cycle of PCR (the DNA-amplifying “miracle technology” that made much of modern molecular biology possible) takes 20 minutes. You might be able to get that down to 10, but a single cycle only doubles the amount of target DNA. In practice, multiples of 1000 (10 cycles) or more would be needed.
If modern medicine can’t do an “instant test” from a nasal swab, it’s far less likely to be able to do it on air it gathers as you (e.g.) as you pass through a metal detector. That’s simply a much harder test.
As a molecular biologist and physician, I would consider instant airborne detection a very far-fetched possibility. If you want to avoid a contagious person, avoid those who are coughing, sneezing, bleeding or visibly ill. Like many pieces of common sense, this will catch most of the problem, but it’s somehow unsatisfying.
This is not medical advice or deeply considered prognostication.
Say what?? I do PCR every day at work. One cycle takes maybe a minute. Less if you’re using more advanced technology. We routinely do 30-40 cycle programs in a half hour or so.