infectious disease
revere | September 1, 2009It's not Labor Day yet, but I guess the Reveres have to consider their vacation over. We're all back at our respective home stations. We admit that not watching flu evolve daily was a relief, although we did sneak peeks when we weren't supposed to. But it also proved to be like the stock market. The daily ups and downs sometimes obscure the bigger picture. So what does it look like now?
We have two contradictory impressions. One is that the pandemic has continued to develop in a very robust fashion. So it's a dynamic picture of change. The second is that it looks like a normal pandemic, just…
revere | August 9, 2009The other day we did something we don't like to do when talking about flu, we made a prediction. We predicted a bad swine flu season in the fall in the northern hemisphere. The history of flu epidemiology is that making predictions is dangerous. Flu has the ability to make fools out of anyone, regardless of expertise. One commenter in particular disdained the risk we took as being no risk at all. It was perfectly obvious to him (or "anyone paying attention") that next flu season would be a swine flu horror show. It may well be, and then this commenter will certainly gloat and perhaps have…
revere | August 6, 2009Making predictions about something as unpredictable as flu is foolhardy. I rarely (if ever) do it, but I'm going to do it now. I am predicting a bad and early H1N1 swine flu season in the northern hemisphere next fall and winter. The reasons for this departure from our usual custom is a paper in Nature from 2007 I just re-read. It's entitled "Seasonal dynamics of recurrent epidemics" by Stone, Olinkyl and Huppert from Tel Aviv University and it appeared in vol. 446, pp 533-536, 2007 (doi:10.1038/nature05638; html version here, if you have a subscription). The paper isn't specifically about…
revere | August 5, 2009I have a reflexive skepticism about some conventional flu wisdom. There's so much about flu we don't know and even more we think we know that we find out we're wrong about. But skepticism is an occupational hazard of epidemiologists. Our training and practice focusses on detecting subtle biases that can produce misleading interpretations of data. When it comes to the commonly recommended personal protective measures for pandemic flu, our skepticism is all the greater since there is so little data to be skeptical about. The lack of data isn't an accident. If you think hard about it, you can…
revere | August 4, 2009Of the three main modes of infection for flu -- transmission by large droplets, transmission by tiny suspended aerosols, transmission via inanimate objects (also called fomites) -- it is the last that is the least certain but garners the most attention in the form of hand hygiene, disinfectants and now, fear of magazines and toys in emergency department waiting rooms and acute-care clinics in Canada. Here's the lede from an article in the Montreal-Gazette:
All magazines and toys should be removed from emergency department waiting rooms and acute-care clinics to reduce exposure to human swine…
revere | August 3, 2009There's a swine flu pandemic well underway and efforts are being made to reconstruct how it started. But almost everyone who has been following this knows it's not the first time a swine flu virus has transmitted from person to person. In 1976 in Fort Dix, New Jersey there were a couple of hundred cases, with 13 hospitalizations and one death from an H1N1 swine flu virus. The public health response was the infamous vaccination campaign that reached 44 million Americans before being ignominiously halted in the face of two facts: the feared swine flu outbreak never got out of Fort Dix; and as a…
revere | July 28, 2009CDC wants us to get vaccinated for flu every year. Always for seasonal flu, and this year, if there is a vaccine available, for swine flu. They want us to get vaccinated because they think the vaccine works and they want to prevent people from getting influenza, always a dangerous and unpredictable disease, even if most of us usually escape with just a flesh wound. CDC backs up its recommendations by a quite a few scientific studies demonstrating the vaccine is effective, citing figures that the vaccine is 58% effective or 91% or effective or some other number, depending on what group is…
revere | July 27, 2009CDC's Advisory Committee on Immunization Practices (ACIP) recently rolled out their 2009 Recommendations. It's for seasonal flu, for which a vaccine exists, not for swine flu, for which there is (as yet) no vaccine. There is a lot to say on the subject of vaccines (see what we've said over the years under the vaccine category), but this seems like a good time to review some basic terminology, including what is meant by vaccine efficacy or effectiveness and how it is measured or estimated. There's a lot to say, so we'll split this into two posts, and in this one we'll go over some terms and…
revere | July 18, 2009Back in May there were some stories on the wires and flublogia regarding a new study about arsenic exposure and risk of flu. I didn't write about it at the time for purely arbitrary reasons (I was writing about other things), but I noticed it and in fact I know the senior author and his work fairly well. For reasons having nothing to do with flu I revisited the paper the other day, along with a bunch of others on arsenic toxicity from the same group up at Dartmouth (the senior author, Josh Hamilton, has now moved to the Marine Biological Laboratory at Woods Hole, Massachusetts, but I think…
revere | July 6, 2009Flu virus is opportunistic. It takes advantage of any weakness. Seasonal flu picks on the very old and the very young, but pandemic flu has found us old folks tough and the younger amongst us quite tasty. No natural resistance seems to be a flavor enhancer. And pre-existing medical conditions? Quite delectable. So how full is the menu in the prime age range? CDC has just released one of their Quickstat summaries based on household interviews with a sample of the civilian, noninstitutionalized, adult U.S. population. The question the sample was asked was whether a doctor or other health…
revere | July 4, 2009The number of people who die from seasonal flu every year varies greatly from year to year. No one really knows what it is. The most frequently (mis)quoted figure is 36,000 deaths directly or indirectly, although this figure is a long term seasonal average of excess mortality correlated with flu season. We discussed this in more detail in an earlier post and for the purposes of this one, only the rough order of magnitude is pertinent. Let's just say it's in the tens of thousands -- roughly. Let's also agree on the several hundred thousand hospitalizations from flu or flu related illness -- on…
revere | June 12, 2009However this pandemic evolves, we are going to learn a lot about how pandemics evolve -- or maybe even start. A paper just published online in Nature sets out a bit more of what we know about this pandemic strain (yes, we can officially refer to it that way now) and makes some observations about its prehistory (its history before it became known and documented by we mortals). Maryn McKenna has an excellent run-down over at CIDRAP News, which you should read. Here's our take on it.
First, we'd like to make a "meta-science" observation. This paper is unusual in several ways. The least…
revere | June 11, 2009In William Osler's day (turn of the 20th century), pneumonia was called "the old man's friend," because it took the elderly away quietly and with relatively little fuss. It was most often caused by the pneumococcal organism, now called Streptococcus pneumoniae. When penicillin came on the scene in the mid 20th century, there was at last a treatment for pneumonia with this organism, but soon resistant strains developed. S. pneumoniae is a frequent resident of the human respiratory tract and usually causes no problems. But if it gets into the wrong place it can also cause sepsis, otitis media…
revere | June 10, 2009Listening to yesterday's press briefing with WHO's Dr. Keiji Fukuda (audio file here), several things seemed clear to me. The first is that everyone, WHO included, thinks a pandemic is well underway. Second, WHO's efforts to explain why they are not making it "official" by going to phase 6 are becoming increasingly awkward and the explanations manifestly tortured. Essentially what Fukuda said was that WHO was waiting for its member nations to signal they knew it was a pandemic and then WHO would say it was a pandemic. It was reminiscent of the cries of one of the principals of the…
revere | June 9, 2009You learn a lot when you move from investigator to subject. I just heard about Drive-by Tylenol for day-care and school age kids. This is the practice of stuffing a couple of Tylenol down the little tyke's throat to bring down a fever just before entering the daycare center. The objective is to get 4 or 5 hours of work in before being called to school because your child has a fever. The underground lore about it includes not using any flavored Tylenol preps with red dye in them so that when the child urps up everthing after lunch there will be no tell-tale pink color savvy teachers will…
revere | June 8, 2009An interesting piece on an infection trial of novel H1N1 in pigs appeared on ProMed over a week ago, but with dealing with swine flu up close and personal and all, I am only just getting to comment on it. This was a study done in the EU (VLA-Weybridge, Mammalian Influenza Group) to see how easy it was to infect pigs with the human-adapted swine flu, what kinds of symptoms and pathology it produced, and how transmissible it was. The answer seems to be easy, mild and very, in that order.
11 pigs were inoculated intranasally and when they began to shed virus a naive pair of pigs placed in…
revere | June 7, 2009There is no reason why a flu blogger-epidemiologist-physician's family should be immune to flu in the community. And it appears my family is not. My daughter has had a cough for the last few days and Friday night was suddenly seized by nausea, vomiting and fever. Her HMO's urgent care directed her to the Emergency Room of the local hospital where a rapid flu test was positive. While waiting to be seen at the ER, her 10 month old, who had a croupy cough, also started vomiting and was warm to the touch. His (slightly) older brother (2 years) was also coughing. Her husband has a cough, too, and…
revere | June 5, 2009In New York City, an illness termed "mild" for many has killed 7 and put 300 in the hospital. A preliminary analysis of about half of those hospitalized, most (82%) were said to have some underlying medical condition. That's common with flu, but it's also a reminder that one of five were otherwise healthy, and unusually for flu, most of them relatively young (mostly under 65). Similarly, the deaths also had underlying medical conditions but were relatively young (median age 43). The two most recent deaths were in the mid 40s.
So not being old is one risk factor. What does "underlying medical…
revere | June 3, 2009The unpredictability of flu and difficulty of making any predictions with confidence is tiring to repeat and tiresome to listen to. Unfortunately that doesn't make it any less true. There are things we know -- because we see them happening -- and things we don't know -- because the information isn't available (like an accurate estimate of CFR or prevalence) or they have yet to happen.
What we know is that we are confronted with a new influenza virus that is spreading with ease outside of its normal season, is infecting an age group that normally doesn't get easily infected (the 5 - 24 year…
revere | June 1, 2009Since I talk a lot about flu in my real life as well as on the blog, I get questions from moms and care givers who wonder when they should start to get worried about a sick child or relative. It's context dependent, of course. The same symptoms that would be shrugged off at any other time take on a different meaning during a flu outbreak, especially when everyone seems uncertain about what is happening or what might happen. There's nothing irrational about this. Infection with influenza virus is always potentially serious and when the young and healthy are in the cross-hairs even more so.…