The curious case of Dr. Pettenkofer

I want you to come back in time with me to the end of the 19th century. Science was becoming increasingly important in people’s daily lives and it had a lot to say about almost every aspect of life. Cities had grown massively in the past 100 years thanks to the products of the industrial revolution, which were fueled by the application of science. Cogs and belts whizzed and steel lurched to preform the work of a 1000 horses. But something else lurks in the shadows; there are dreadful unknown killers abound. Coughing, wheezing and the sounds of people groaning can be heard as they die slowly throughout the cities. Contagious diseases wrought havoc and destruction on the lives of people all over Europe.

Two of the main ideas about what was causing the increase in disease rates were hotly debated. Infection via organism like bacteria or Miasma (dirty air) which suggested that filth and dirt caused illness. We now know that contagious diseases are caused by viruses and bacteria; but naturally at some point people didn’t know what was the cause of disease. The miasma theory of infection had been wildly accepted for many centuries and took some of sciences best minds to demonstrate that it was incorrect. In fairness which would make more sense to you, that unimaginably small things that you have never seen and can’t see (with out very special equipment) can get inside your body and make you unwell or that things that look and smell bad have a way of passing on their quality of badness on to you. Miasma is still found in our use of language as well, we say to small children that things are dirty or unclean when what we really mean is that certain things might harbor vicious bacteria!

So we had two competing hypothesis and what is the best way to deal with two competing ideas? Do an experiment! The main two players in this story I wish to share, are a one Dr Koch who biology students know from, and giggle at, Koch’s postulates and the singular Dr Pettenkofer who very few biology students know about. This should give you some idea of who was routing for which idea! But there is a twist! During the end of the 19th century on the verge of an outbreak of Cholera in Hamburg which Koch was suggesting based on carful observation and statistical analysis. He even purported that a certain bacteria Vibrio cholerae (which had been independently discovered nearly 30 years earlier) was responsible for Cholera. While Pettenkofer was convinced that the outbreak was due to the high levels of pollution in the city and that infection require 3 separate conditions an x,y and and only when all 3 were present could Vcholeraebecome poisonous. In a way he was right, the pollution allowed for effective transmission of the bacteria but Pettenkofer was of a mind to try prove his point of a tirade of infection and in a big way!

Everyone looked like they did magic in the 19 century

Pettenkofer wrote to Koch and requested he send him a sample of his newly identified bacteria something which microbiologist still do these days. Once Pettenkofer received it, he had an experiment which he thought would prove his point; he was going to drink it! If Koch was right that Cholera was caused by the ingestion (fecal to oral) of this bacteria, then by drinking large amounts of it he would surely get Cholera. So he, a colleague and independent witnesses neutralised his stomach acid (removing this as a factor) and administered the vial of Vcholerae. Pettenkofer learnt something from this, that the V. choleraebacteria did not cause Cholera. All that happened was he felt a little unwell. He certainly did not get Cholera! Pettenkofer thought that this disproved the germ theory of disease. Quite rightly too, he took all the correct precautions to remove any bias from his self experiment.

Koch also spent time trying to develop psychic powers

A little back ground of Cholera may be needed at this point, it is caused by the bacteria Vibrio cholerae, as few as 10 Colony forming units (CFUs are the living and healthy bacteria) are capable of infecting a healthy person. Pettenkofer drank as many as a billion CFU’s! V. cholerae releases a toxin which alters how cells hold on to water leading to horrific diarrhea. One of the only real treatments is fluid replacements. Cholera is still deadly and a big problem in confounding issues like earthquakes and other natural and manmade disasters.

So the question is how did Pettenkofer survive or at least come out with his trousers clean! Allow me to put forward my own pet theory, V. cholerae has a interesting life style. It is highly infection at low levels. Once the level of V. cholerae bacteria builds up in an infected person a change occurs in the biology of the bacteria. Instead of becoming more virulent (how sick a bacteria makes you) V. cholerae turns off its virulence; it shuts down its toxin production and turns on its little out board motor known as flagellum and swims off down stream off to infect another person. I’ve mentioned this process before, its known as quorum sensing. Bacteria release a small molecule into the environment (soil, petri dish or intestines), they use these molecules as a census in which they chose how to act as a group. Most bacteria, to our knowledge, use these molecules, and many use it in order to work out when to become virulent. V. cholera however works the other way around; it counts these votes and when a certain level is reached it turns off its virulence.

So Pettenkofer could have survived by this little biological trick. If the V. cholerae he drank was at a high enough density its virulence would have been turned off leading to it just passing right through him. If he hadn’t played fair and had failed to neutralised his stomach acid then he might have become fully infected and suffered greatly at his own self experiment or at the very least would have required a new pair of trousers.

So what became of Pettenkofer, his results were largely ignored and moved into obscurity after some very good work promoting hygiene. Koch had just been consulted on a new water system for the city of Munich. In the city there were certain streets where one side had their water supplied by the newly designed water system, developed by Koch which could filter out the V. cholerae, while on the other side of the street water came from the Vcholerae infused local stream. This lead to situations where one side of some streets had Cholera while the new water system side was clear of Cholera. Pettenkofer carried on working in to his old age until depression took over and he ended his own life alone one evening. Koch isolated the bacterium that causes TB, discovered a way to isolate anthrax from blood samples, rediscover the Vibrio cholera and went on to win the Noble prize in 1905 for “his investigations and discoveries in relation to tuberculosis”.

Although Pettenkofer was wrong about his idea which could only have been confounded by his positive results disproving the germ theory I greatly admire his bravery. Even knowing in far greater detail then either man knew of bacteria in their days, I would never dream of drinking a vial of live V. cholerae. Pettenkofer’s principles of testing his ideas is the foundation on which Science progresses and we should, for at least that, recognise him.