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  • Alex Cloherty

A short microbial history: Part I

This is another post inspired by a question from a friend. She asked about how the conception of bacteria and contagious diseases, and just generally health and illness had changed over time and across the world. This is an enormous question, but I'll do my best to do it justice and give an overview of the history of medical (micro)biology over the next two weeks!

First, an aside: for practical reasons, I'm focusing today on the major cultures with strong written records. No offense is meant by leaving out any culture in particular - I'm just working with what I can find. If you have some knowledge about the medical history of additional cultures that you want to share, I'd love to hear from you, and maybe even add a third part to this overview!

Now, let's begin by establishing one major timepoint. Before the mid-1800s in Western Europe, as far as I know, there was no conception of disease being caused by tiny organisms invisible to the naked eye. It was only around this time that the "Germ Theory of Disease", or the general theory that diseases are caused by microorganisms, began to be accepted. This is not to say that there weren't concepts of contagion, just that there was no discussion about 'invisible animalcules' (we'll get back to that later) being passed around.

From here, let's take a big step back, to some of the most ancient civilizations. In ancient Greece, ancient China, and ancient India, there was a focus on balance, or harmony, in medicine. You might have heard of the ancient Greek system of 'humorism', in which a balance of the four 'humors' (black bile, yellow bile, blood, and phlegm) was thought to be necessary for health. According to this theory, all disease resulted from an excess of one of these 'humors'. Somewhat similarly, in ancient China, diseased was conceptualized as a disbalance of six 'excesses': wind, cold, fire, dampness, dryness, and humid heat. Comparably, the Indian system was made up of three 'doshas', which are more difficult to translate. Simply put, one was air-like, one was fire-like, and one was water-like.

All of these ancient civilizations had extremely detailed systems, and various symptoms were associated with particular disbalances - for instance, too much yellow bile led to liver problems in Greece, and excessive wind gave rise to tremors in China. These systems were also on to something: there was a holistic emphasis to medicine, with focus not only on the best treatments that doctors could offer at the time, but also a consideration of factors such as diet, exercise, and mental health. It was only recently that modern western medicine once again discovered an appreciation for those factors. However, as far as I can tell, none of these ancient systems had a concept of contagion per se. For this, we have to speed forward in time and travel to different civilizations.

In medieval Islamic society, there is evidence that an understanding of contagion was emerging. For one, there was an Arabic word for this concept: adwā. This word was used in medical books to reference the dangers of being close to sick patients, for instance. Furthermore, and remarkably, antisepsis during surgery (prevention of infection by microbes) was already used in Islamic societies during the middle ages. This was centuries before medical experts in the West came up with the same idea. Ancient Islamic doctors washed patients before surgeries and disinfected with materials like wine, vinegar, salt water, and mercuric chloride, all of which indeed help prevent bacterial growth. As a side note, Medieval Islamic doctors also used a form of anaesthesia, altogether making surgery at least a little less terrifying and deadly in Islamic society as compared to European society at the time.

It was much later, Vienna 1847 to be precise, that the Hungarian physician Ignaz Semmelweis made a discovery that almost led to the inclusion of antisepsis in Western medicine. Semmelweis noticed that women who gave birth assisted by doctors whom had just performed autopsies were more likely to be infected than women assisted by midwives, who didn't perform autopsies. Upon forcing doctors to wash their hands prior to delivering babies, mortality rates were reduced more than ten-fold in his hospital. Sadly, his colleagues resented the implication that they were 'unclean'. Not only were Semmelweis' theories rejected, but he ended up in a psychiatric institute, where he eventually died... Of an infection.

It is notable that Semmelweis' sad demise happened long after the discovery of microbes. In the 1640s or 1650s, the German scientist Athanasius Kircher used a microscope to study the blood of victims of the plague. He recorded seeing 'animalcules' in the infected blood, and hypothesized that the disease must be transmitted by these strange little beings. Not long after, the Dutch scientist Antoni van Leeuwenhoek also observed 'animalcules' - in pond water, on his own teeth, and everywhere else he could look. van Leeuwenhoek's work seemingly caught more attention than Kircher's, and spurred on scientific work in the field of infectious disease throughout the 1700s. Sometimes, it's just about being in the right place at the right time.

Next week, we'll carry on with the work of three more modern medical microbiology giants who revolutionized the study of infection disease. Until then - wash your hands!

- Alex

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