White Coat Underground

What happened to the flu?

A month ago, I was diagnosing several cases of influenza-like illness (ILI) every day. Then, as suddenly as it began, it disappeared—no ILI, no positive nasal swabs for influenza A (and hence H1N1/swine flu)—just the usual strep throat, poison ivy, ankle sprains, etc. So what happened?

The new influenza A/H1N1 (hereafter called “H1N1” or “swine” flu) emerged early this year and rapidly became pandemic. It caused a “second” flu season, ramping up just as the usual winter flu epidemic was winding down. This graph shows vividly the two-peak flu season we have this year due to the new flu.

As others have discussed, it is not unusual for a novel, pandemic flu strain to come in waves. As the first wave of H1N1 leaves the northern hemisphere and takes root in the southern hemisphere for their flu season, what may we expect next? Or is the “first wave” even done with us yet?

One possible answer to the sudden absence in swine flu in my daily work may be the end of the school year, the removal of kids from the crowded environments that they inhabit during the rest of the year. And where do these kids go when not in school? Many of them go to summer camps, where H1N1 may find a comfortable place to hang out. It’s still early in the camping season, but in parts of the country where camps start early, they are seeing cases of H1N1 flu.

A brief google search reveals different ways in which summer camps are dealing with influenza-like illnesses. For example, in Ontario, Canada, health officials recommend against testing for flu and base guidelines on clinical circumstances. Some camps have temporarily shut down, others have sent sick children home, and others have implemented screening, control, and isolation programs within the camp, especially those that are geographically isolated. One summer camp sent out this letter:

As has always been the case at this time every summer, four campers have presented themselves to our Health Centre with fevers and/or flu symptoms. And as is always the case, our MASH staff have responded expertly and quickly to provide a comfortable and isolated space for these kids to begin the process of getting better.

Sending kids home to recuperate is one of the options that we have available to us in this sort of situation.

We have decided it to be prudent to send these campers home for a few days until they are cleared by their doctor to return. Our motivation is:

1.To provide the most comfortable space for kids to get well and

2.To protect our overall (and overwhelmingly!) healthy population from acquiring any contagious illnesses.

All four of the families have been contacted and are cooperating with this decision. We are helping with their camper’s transportation to their hometown.

Yes, we are acting particularly cautiously in this summer of 2009 while fears of the spread of H1N1 flu through the cities remain significant.

We also wish to inform you that there are a number of practices that we initiated this year to protect our population:

1.Everyone coming in and out of camp from the “outside world” is screened before being admitted to camp. (This includes staff on days off, canoe trips, field trips, inter-camp, and individual “ins and outs”)

Definition of “screen”: Their temperature is taken, they are asked a series of diagnostic questions, and they are watched while washing their hands.

2.The cabin groups (including staff) of campers with a fever are screened twice in the first day and then periodically over the next week.

3.We are delivering specific, repeated, and targeted education about coughing safely and proper handwashing practices.

The reason for this communication is strictly to keep you informed, to let you know that there are some kids who are sick at camp, and to let you know that we are doing our very best to take reasonable and appropriate steps to protect our campers and staff.

One camp, which news reports did not identify by name, voluntarily shut down after experiencing a large flu outbreak. This does not, however, appear to be the norm. After communicating with several summer camps across North America, it would appear that many are experiencing small outbreaks of ILI which they are containing within the camp environment, and have implemented increased prevention and control programs.

What’s the lesson here?

As has been known for at least a century, crowding helps the spread of influenza. It would also appear that aggressive prevention and control programs can mitigate this spread. During the current pandemic, should we be keeping kids away from schools, camps, and other areas where flu can be spread? Is this pandemic worrisome enough that we should, during this Depression, halt necessary economic and educational activities? Remember, when a kid stays home from school or camp, a parent stays home from work or vacation, both of which are income-generating activities. These sorts of questions were asked during the 1918 flu pandemic, which attacked while the US was preparing for and fighting a war. It was not clear to health officials then what necessary activities should be curtailed to help stop the spread of flu (and of course politics made decisions doubly difficult).

For better or worse, time and science will give us more insight into these questions. If there is to be a “second wave” of H1N1 in the fall/winter flu season, our current experiences may serve as a guide for how to control the next phase of the pandemic, should it arrive. Meanwhile, my kiddo is going to camp, I’m going to work, and life continues on nearly as always.

But I do carry a bottle of hand sanitizer with me wherever I go, and I never touch a doorknob. I’m not so fond of shaking hands, either.


  1. #1 Michael Simpson
    July 12, 2009

    I would like to propose another theory. A large group of Americans do not visit their PCP or an Emergency room if they get the flu. Most of them, myself included, lay in bed, whine to their partners, watch a lot of TV, and a few days later, get up and go to work.

    During the massive news about H1N1, I think there was a big uptick in the number of individuals who did visit their physicians to make sure they weren’t going to die. Now that the news has disappeared, people are moving back to their old ways of dealing with the flu, and we have the downtick.

    Additionally, although classrooms are a crowded environment, so are baseball games, closed-in offices with adjoining cubicles, and movie theaters. If the disease was still about, all of those situations would be as much a petri dish for the virus as schools.

    So, I wonder if there’s a statistical problem that’s causing misinterpretation of data.

  2. #2 Denice Walter
    July 12, 2009

    My cousin works for a high tech company which is run(ruled?) by the founder/inventor who doesn’t tolerate people taking sick days unless they’re *really* in bad shape.In early June,she started feeling ill, had a fever,saw a doctor, was tested for H1N1(negative),got a *higher* fever,and finally stayed homed.She returned and discovered that others had also delayed staying home from work and were slowly recovering.The really crazy thing is that “Castro”(her secret nickname for her boss)is about 80,has a serious heart condition(closely monitored by a well-known cardiologist whose office is about 2 hours away *by air*)and thus is probably placing his *own* health at risk as well as that of his employees.

  3. #3 antipodean
    July 12, 2009

    Thanks for that CDC graph- It’s very interesting.

    PAL wrote “What’s the lesson here?”

    Don’t rely on your own clinic sample to extrapolate to the whole population? The whole population these days is world-wide.

    It’s the middle of summer in the USA- so not so much ‘flu. It’s the middle of winter in the Southern Hemisphere and we are swimming in ‘flu cases.

    Wait till the weather cools in your neighbourhood again… Let’s hope it doesn’t mutate into something with a higher case-fatality rate.

  4. #4 PalMD
    July 12, 2009

    Of course you’re right, but my point was more that there is still plenty of flu in the Northern Hem despite it not being “flu season”.

  5. #5 Mara
    July 12, 2009

    I agree with the first commenter above. My husband developed an ILI last week. I told him that if he had the flu, he had to see his doctor immediately if he wanted any treatment.

    Obviously he didn’t listen to me. ::cough:: So once the 2-day limit for antivirals was past, he didn’t bother going, because the doctor couldn’t have done anything for him anyway.

    Now when our daughter spiked a fever, we took her to urgent care immediately. Fortunately, she turned out to have a random childhood virus, rather than the flu.

  6. #6 Rowan
    July 13, 2009

    I recently flew on Alaska Airlines out of LAX. The cabin temp was on the chilly side even though i was wearing two shirts and a cardigan sweater. I asked for a blanket.

    The flight attendant indicated they no longer distribute them due to the H1N1 flu virus as they do not clean the blankets or the pillows.

    On the other hand the Qantas flights I was recently on provided blankets which were sealed in plastic.

    What I found discomforting were the number of people who were very obviously sick but were permitted to fly. For instance, the woman seated next to me went through the equivalent of a box of tissues due to a runny nose with coughing and sneezing for fifteen hours continuously. When I asked her if she was coming down with or recovering from she indicated she was recently ill and had to get home. Um, yeah…

    I was concerned I would contract whatever she had during my holiday which would have been a complete downer. Frequent hand washing and keeping my head turned away from her was my only defense. Flight was completely full so asking to be seated elsewhere was not an option.

    On another Qantas flight during the same trip there was a man in the row behind me coughing the entire flight from Melbourne to Brisbane.

    Once in Melbourne passengers were screened for fever, but that doesn’t do much good if you aren’t screened at the point of departure.

    I can understand how the guy with TB managed to fly from Europe to Canada last year. He didn’t indicate to anyone he was sick with it. There is the innate desire to be home when you don’t feel well.

    I cringe every time I fly knowing I will be on an aircraft with literally hundreds of people who may or may not be contagious with something.

  7. #7 DLC
    July 13, 2009

    Excuse what may be a basic question, but why is it these flu strains seem to pop up more in the wintertime than summer ?
    Do people’s immune systems become weaker in winter, or is it the cooler weather ? Has anyone even researched this ?
    Just curious.
    Oh, and Welcome Back, Pal. Hope the summer trip recharged your batteries.

  8. #8 PalMD
    July 13, 2009

    @DLC, there’s a number of theories, none of them yet satisfying. One is increased indoor crowding in winters. A more recent idea has to do with the physical properties of the respiratory droplets coughed up and how they respond to various temps and humidities.

  9. #9 Paul Heikkila
    July 13, 2009

    The flu will “disappear” when people stop reporting it. Early on in the US, New York took the lead in number of cases. Later New York was passed by Illinois. Mayor Bloomberg was asked why Illinois had passed New York, and he responded that if you wanted to see more cases, then we could test more people. Once it was determined that the treatment for H1N1 was the same as the treatment for seasonal flu, what was the point of testing?

  10. #10 BB
    July 13, 2009

    John Barry in his book “The Great Influenza” noted that the flu pandemic of 1918 was marked by an initial flurry of cases, then a lull before the big outbreak. Here’s hoping that if the pattern holds now, the vaccine is out by October.

  11. #11 Tony P
    July 13, 2009

    I once worked in an office where a high percentage of my co-workers had kids under 8 years old.

    So the kid would get sick, mom and dad sick, dad and/or mom would come to work and spread the joy around.

    I’ve never been sicker in my life than when I worked there. If your kid is sick, keep em’ home. And if you’re sick, stay home.

  12. #12 hmd
    July 13, 2009

    Air Force Academy basic training:

    Out of about 1300 incoming basic cadets, 89 have presented with flu-like symptoms, 15 of those confirmed H1N1.

    Sick cadets are isolated in a sick dorm. Apparently healthy basic cadets are restricted to base. (Seems rather draconian, until you remember that basic cadets are mostly restricted to base anyway – but now they’ve canceled their few opportunities to leave.)

    The usual hand-washing precautions are in place also.

    So, yeah, flu isn’t entirely gone. This isn’t too surprising, given a sizable number of people from all over the country in such close contact. But definitely much more than normal.

  13. #13 PalMD
    July 13, 2009

    In 1918, military bases were the worst of the worst.

  14. #14 Dunc
    July 14, 2009

    But I do carry a bottle of hand sanitizer with me wherever I go, and I never touch a doorknob.

    I predict an epidemic of OCD handwashing in the near future…

  15. #15 jay
    July 14, 2009

    I cringe every time I fly knowing I will be on an aircraft with literally hundreds of people who may or may not be contagious with something.

    I think we has a culture have become too germ phobic. We are living closer and if the planned community and mass transit advocates have their way we will be encountering lots of sick people in close quarters every day. But they need to travel too. Most people can’t put their lives on hold for a cough, or even a mild fever.

    [My wife has frequent substantial coughing spells. 2 stays in a hospital and multiple diagnostic tests by multiple specialists have failed to identify any (much less contageous) cause. But it’s not feasible to plan to fly somewhere because of the risk that some overzealous airline employee or frantic passenger will decide to kick her off the flight]

  16. #16 katydid13
    July 14, 2009

    Someone I know has suggested that we lock the kids down in their schools and camps since they are such efficient little germ spreaders.

  17. #17 Paul Heikkila
    July 17, 2009

    There’s been much comment that H1N1 does not seem to particularly affect the elderly. This is attributed to their having some immunity. Is this an assumption, or is there some firm reason for stating this?

    Could it not be that the elderly are not affected because they are more watchful for infection? Since the emergence of hospital transmitted diseases, such as C.diff., hospitals, nursing homes, and assisted living facilities have ramped up their procedures to try to quell such outbreaks. Perhaps the serendipitous result is that other conditions, such as H1N1, are nipped in the bud?

New comments have been disabled.