Non-symptomatic cases make newly identified diseases less scary

If you've been following news about the H7N9 bird flu outbreak in China, it may be relieving to know that doctors are now looking for (and finding) people who are infected with the virus, but who appear perfectly healthy or who are just suffering from a mild case of the yucks. It's an important reminder that we identify new diseases when sick people show up, very sick, in hospitals. Just because those are the only people we know to have the disease, doesn't mean the disease makes EVERYONE that sick. Hidden in the background are often many, many people who shrug off a new flu the same way you or I have shrugged off an old, boring flu. This is context you should take into reading about every new disease.


  1. “This is context you should take into reading about every new disease.”
    but, as it is science, you must still treat every new disease/flu strain as an anomaly, lest you start assuming it’s not that bad, and the nastiest bug ever comes along (due any time now).

    1. It makes sense for scientists to treat it that way, absolutely. But I’m talking to the public here, who have to interpret news stories that often convey the alarming news without providing the context. People have contacted me who are terrified of new flu like this, because all they hear is that it kills most of the people who contract it. They don’t hear that those are the only people who get tested for it. For the public, this context matters, and it makes a hell of a lot more sense from their perspective to assume this is happening rather than to assume it is not. 

      1.  Perhaps you should write an article that is more informative? A lot of the fear that people express when it comes to new strains of flu being reported is due to the fact that they don’t understand much about the flu. Every time there is an article posted about something as straightforward as vaccination there are tons of posts where people seem to believe that new flu strains are due to the overuse of antibiotics. There are also posts about how vaccines are “unhealthy because they are injecting you with antibodies”… there are even people claiming that having a “healthy gut” will protect you from a severe strain of influenza even though some of the dangerous strains cause cytokine storms in the young and healthy. Providing context is great. every influenza article should provide more information about the flu, how surveillance is conducted, and why monitoring the situation is important. Frankly we need a public health campaign in the US that at least informs the public about viruses vs bacteria. When you imply that this is probably just “the boring old flu” you are doing people a disservice. It downplays the current situation makes people less likely to trust experts in the future. The number of people that started claiming “its all hype” immediately after the first publications is sickening. The fact is this may be the boring old flu, or it just might be severe. The asymptomatic case means there probably are other cases out there that are not severe which is good news for a few but can be bad news for others. It means the virus has more chances to mutate. The more chances it has, the more likely it is to develop the ability for human to human transmission. Also… the 1918 flu “only” had a mortality rate of 1 to 5%. Flu should be taken seriously every time.

        1. A healthy gut won’t help you much, but boy will a bad flu leave the gut you started with damaged. I’ve only caught flu twice in my life. The first time I don’t know if vaccines were common, and it was pretty mild. The second time convinced me to try the vaccine no matter what (around that time at least locally they were asking that younger healthier adults defer to small children and the elderly). I was flattened for a week, weak and sick for another week, my body didn’t work properly for yet another week, and I ended up with breathing complications that then lasted for over a month, and then I developed pleurisy. I have no idea if it was a “scary” flu or a mundane one. I just know it really really sucked.

          I still wonder if it was connected some how to the activation of my autoimmune disease. Not long after I got better I started coughing again, and then rapidly declined… then was diagnosed with Hashis.

          1. My temperature jets up to 103° – 106° at the slightest provocation.  I get vaccinated for everything.

          2.  I also developed pleurisy and secondary complications after my last flu. I spent the next several months in and out of the hospital.  I can’t imagine what a new severe strain of influenza would do to me. Best of luck to you.

  2. Actually, respected scientists have pointed out that asymptomatic patients are a significant development with a virus that has never caused significant sickness before. The possibility  of  mutations to the virus in a large reservoir of humans could lead to improved  H2H transmission sooner rather than later. You are missing the point that H7N9 has not been seen in significant numbers in humans prior to this outbreak.

  3. Your take is exactly the opposite of the one that scientists are holding. Asymptomatic infections  are a bigger problem because they are silent/stealth carriers. Also each host provides a new platform for the next mutation or gene recombination, which could prove to be the one that makes human-to-human transmissions possible. People who don’t understand science should not write about it. People who are in the know on this subject are plenty worried and should be. 

  4. I like that (so far) two of the comments on this article presume to speak for “scientists” without citing a single source.

    1. Date: Sun 14 Apr 2013
      From: Anne DeGroot [edited]

      Scientists at EpiVax performed an extremely rapid bioinformatics analysis on the genome sequences of H7N9 influenza and predict that it will be difficult to make effective vaccines and low cost diagnostics for the newly emerging virus (also called H7N9/A/Shanghai/1/2013), meaning that the new H7N9 may be a “stealth” virus that is able to fly under the immune system’s radar. And, they predict, should the H7N9 “stealth virus” adapt itself for human-to-human transmission, it has serious potential for rapid expansion on a global scale.

      What makes the new flu invisible to the immune system? The protein that is usually incorporated in vaccines known as HA (hemagglutinin) has fewer immune-stimulating “T cell epitopes” than many previously circulating strains of flu (see image at

      The analysis done by the EpiVax team of expert vaccine designers is consistent with reports that previous H7 vaccines also had low immunogenicity. Last season’s [2011-2012] H3N2 was also predicted by EpiVax to be low immunogenicity, and epidemiological evidence of outbreaks among H3N2-vaccinated individuals confirms the prediction. Unless it is engineered for higher immunogenicity, a vaccine against H7N2 may have similar low efficacy as was seen with H3N2.

      Low T cell epitope content generally means that it is harder to make high-affinity antibodies, the type that protect against flu and that are used to make low-cost diagnostic tests like ELISAs. While one rapid test for flu (based on PCR) is available, lacking a low cost rapid test, it could be harder to screen the expanding numbers of individuals that have already been exposed to active H7N9 cases. More than 1000 such cases are being “followed” by Chinese health authorities.

      The EpiVax scientists did a similar analysis of pandemic H1N1 in 2009 [1] and correctly predicted that pandemic H1N1 would not cause severe disease in most individuals, a prediction that was subsequently validated in vitro and in vivo by many others. Unfortunately, the immunogenicity news is not so good for H7N9.

      Detailed information with references/publications can be found at

  5. You all are missing the big picture: the only way to win is to get your completely innocuous,  asymptomatic virus to infect every country in the world first, including those damn islands, before upping the severity and alerting the world health organizations.

    Sorry, where am I? Been playing too much Pandemic.

  6. >I like that (so far) two of the comments on this article presume to speak for “scientists” without citing a single source.

    I guess that’s two commenters who are more up on the situation than others and who don’t feel a pressing need to provide a link for your lazy ass. Sadly, viruses don’t care about your pandemic fatigue.

  7. Or more scary, as it means that anyone with the sniffles might be harbouring your death-plague. 

    In entirely unrelated news, I’ve got a homeopathic treatment that will protect you from all illnesses, for a very reasonable fee…

    1. Until Tamiflu came out, modern scientific medicine could offer you vaccines to prevent the flu, but if you got it anyway they didn’t have any way to treat the virus itself, just things like aspirin and chicken soup to help the symptoms. 

      Homeopathy is a bogus quack theory with a couple hundred years of badly run trial&error experimentation, so it’s not something you can trust to actually cure diseases, but it does sometimes find treatments that will mitigate symptoms.  I’ve found some homeopathic pills that fairly consistent reduce flu symptoms from “feeling awful” to “not quite as awful”, which is a big win.  (And they’re solid pills, not diluted-to-nonexistence liquids, so it’s not guaranteed-to-only-be-placebo, but if what you’re trying to do is just reduce symptoms and discomfort, placebos are fine as long as they work for you.)

  8. The previous “Oh, no, we’re all going to die!” H5N1 bird flu was a major news item during the early-middle Bush Administration years, when maximum scariness was a politically valuable feature, when they had sold the Iraq War based on Saddam’s bioterrorism and the 9/11 Anthrax plague and the FBI kept announcing how well they were doing in finding the REAL Anthrax terrorist (this time for sure!), and every major holiday had speculation from your local TV station about how “credible terrorist chatter” had indicated some non-specific plans and you’d better stay away from $YOURCITY’s major landmarks, and the National Guard was stationing tanks to protect the Golden Gate Bridge and the Army or Homeland Security were busy protecting other bridges and nuclear power plants and city halls around the country and telling you to watch out for suspicious foreign-looking people in your local train station or subway or airport.

    Fortunately they’re not busy playing those particular games right now, so it’s possible that we can get some decent science reporting on the actual threats.  And at least the name H7N9 means we’re not going to have to hear clueless reporters talking about how dangerous the “HSNI” flu is (yeah, one “expert” really didn’t understand that it was H5N1 and not a mis-typed acronym on their teleprompter; I think it was on a national radio station’s news coverage, though it might have been my local traffic&weather news station.)

Comments are closed.