William McNeill’s “PLagues and Peoples” contains a historical tidbit I hadn’t heard of before. An early form the germ theory, or “contagionism” could be traced back to Girolamo Fracastoro in 1546. In 1822 it was tested by French doctors against its rival, the miasma theory. There was an outbreak of yellow fever (now known to be carried by mosquitoes) in Barcelona and experts led by Nicholas Chervin determined that the victims could not have come into contact with one another to spread the disease. This bolstered arguments by reformers that quarantines were an irrational obstruction resulting from Roman Catholic medieval superstition. Even John Snow’s tracing of cholera infections in London to a faulty pump did not overturn that view because it was only circumstantial evidence. What finally changed things was microscopes that could actually show the infectious organisms. But even Robert Koch and Louis Pasteur’s work did not stop a German doctor in 1892 from acting as a proto Barry Marshall and drinking a beaker full of cholera germs (he was lucky and reported no ill effects). That same year in Hamburg (a latecomer to modern sewage systems), one half of a street became infected with cholera while the other was spared. The infected half drew its water from the town of Altona which had installed a water-filtration plant to sent their sewage elsewhere while the spared half drew clean water from the Elbe. The Hamburgers decided both that the miasmatic theory could explain such results and that it was better to give than receive in the case of sewage.

Another surprising claim is that quinine merely suppresses fever, but does not prevent or cure disease. It seems strange then that this enabled the exploration of non-coastal Africa, since I had always heard that fever is just the body’s natural defense against such infection, making its suppression as hopeless a means of preserving life as the a Russian zoo’s attempt to ward off cold among its animals with vodka.

On finishing the book I suppose I should give some overall thoughts, but I think I’ve already said enough in previous posts. I didn’t previously mention the author’s pessimism regarding the population increases resulting from taming infectious disease. I suppose it was common at the time the book was written.