H. influenzae—it ain’t the flu, but it’s still pretty cool

This was first posted at Science-Based Medicine on Monday, but I can’t seem to keep myself from cross-posting. –PalMD

I’ve been thinking about an interesting organism lately, an organism that illustrates some basic principles in science-based medicine.

The organism is called Haemophilus influenzae (H flu), a gram-negative bacterium discovered in the late 19th century. H flu has a great story, both in historic and modern times.

The brilliant microbiologist Richard Pfeiffer isolated H flu from influenza patients in the late 1800’s (hence its name) and for many years, it was believed to be the cause of the epidemic illness, and when the flu pandemic of 1918 hit, researchers worked tirelessly to develop anti-sera against H flu.

But some things weren’t adding up. As thousands died of the flu, doctors were isolating H flu from victims, but also other virulent bacteria such as Streptococcus pneumoniae. Influenza was decimating military camps, and was seriously degrading our ability to fight in WW I, so military bases were a focus of research. Doctors looked for H flu in patients, but could not find it consistently. For example in Camp Dodge, Iowa, an autopsy series showed H flu in only 9.6% of victims.

Some researchers were focusing on something else.

It was found that when sputum of flu victims was sent through filters too small for bacteria to pass through, it was still infectious. These “filterable agents” were known as “viruses”. But even into the 1920’s and 1930’s, it was not clear if H flu played a significant role in influenza, or if a virus was to blame. Interestingly, at a time when women couldn’t yet vote, women physicians and scientists were at the forefront of this medical battle.

As the evidence mounted, the decades-old belief about the role of H flu in influenza (which was held with some skepticism) was abandoned, but the world wasn’t done with H flu.

H flu doesn’t cause “the flu”, but it does cause some pretty nasty human diseases, especially in children. It was a common cause of ear infections, pneumonia, meningitis, and epiglottitis. The last is especially frightening. A toddler may begin with a sore throat, and rapidly progress to difficulty swallowing and breathing. If not treated quickly, the child asphyxiates. Taken together, H flu in children had a fatality rate of about 5-6%.

Since a vaccine against H flu subtype b (Hib) became routine in 1990, the incidence of H flu disease in children has decreased by about 99%, from around 40-100 cases per 100,000 to about 1 case per 100,000.

This is one of the great vaccine success stories. From personal experience, I can tell you that few things are as grave as standing in front of a parent clutching a child who is struggling for breath, drooling, and speaking only enough to say, “Mommy, help!”

The infectious disease promotion folks, such as “Dr.” Jay Gordon may want to read a little history, a little microbiology, and a little epidemiology before telling others to endanger their children.


Barry, John M. The Great Influenza: The Epic Story of the Deadliest Plague in History. Published by Penguin, 2005. ISBN 0143036491, 9780143036494

Wollstein, M.D., Martha. Pfeiffer’s bacillus and influenza, a serologic study. Laboratories of the Rockefeller Institute for Medical Research. 15 July 1919.

Coca, Arthur F., Kelley, Margaret F. A Serological study of the bacillus of Pfeiffer. New York Hospital and the Department of Bacteriology in Cornell University Medical College, New York City. December 13, 1920.


  1. Christophe Thill
  2. James Pannozzi

    PalMD, speaking in his ussual overweening, condescending and self assured tone, states:
    “I’ve been thinking about an interesting organism lately, an organism that illustrates some basic principles in science-based medicine.”

    Interesting post which somehow takes a decades long misunderstanding and lack of knowledge of viruses and turns it into a glorious triumph of “science” based medicine.

    Until the virus explanation was finally discovered thus exposing the reason that the “filter” did not work, shall we assume that what they were doing was NOT “science” based??

    You do see the point, I hope – the existence of unknown things does NOT disqualify some area of medicine from being “scientific”. Right now, Homeopathy has come in for a lot of unmerited criticism (mixed in with some which is deserved). And there are plenty of crap tests and goofy theories and unqualified people running around calling themselves Homeopaths to give ample credence to denialists who shut off their thinking AND their eyesight the moment REAL scientists and researchers publish real research and real Homeopaths (many are MD’s, others are not but have completed qualified training) indicate powerful clinical support of efficacy well above placebo.

    This phenonema is by no means limited to CAM. The famous example of the severe and unwarranted scepticism heaped on Barry Marshall when he attempted to publish research on H. Pylorii. Journals at first refused to publish his research. Later he got published giving good research results but STILL many critics were not satisfied – so great was the entrenched orthodox view that what he was saying could not be
    and “went against” “accepted” science. Finally I guess the poor guy just got fed up and, without telling anyone of his plan, actually ATE some of the bacteria (gulp!) and then demonstrated signs of pyloric ulcer. THAT seems to have done the trick though, unless I am mistaken, it was another 5 years to a decade before begruding admission was finally made – the Nobel prize must have helped.

    Unreasoning scepticism, the blind assumption that nothing new can be found which will contradict known science and the dangerous attempt at suppression of research by science writers, media innuendo and Doctors who should know better shouting about “science” and “evidence” based medicine, the delusion everything was being deduced geometrically from first principles – all this just delays progress and prolongs mistaken science though it may add to the coffers of entrenched interests who like current science, the good and the bad, just the way it is.

    Regarding this you might want to read
    Pseudoscepticaemia: signs, symptoms and socks
    at THIS link:

  3. JustaTech

    Pal, is there any way to know now about the causative agent in an individual case of a disease in the past? My brother had meningitis as a baby, before the Hib immunizations were standard, and I wondered if it was likely that he was cultured in the PICU for the specific bacteria that made him sick, or if they say “who cares what it is, kill it!” and just plunge in with the antibiotics. It’s something I have been wondering about.

    Also, wasn’t there a deaf Miss America who lost her hearing to Hib, but for years told people it was vaccines?

  4. I don’t know what the rate of successful culture is, but usually with bacterial meningitis we get a definitive microbiologic diagnosis.

  5. Richard Eis

    and your actual point once you finished blathering on randomly was what exactly Mr Pannozzi? That science evolves and gets better over time? That scientists don’t run off believing anything at the drop of a hat?

    Homeopathy is a pathetic joke and has always been. A 5 year old could explain why banging water about doesn’t make it cure stuff. I suggest you go find one.

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