antibodies. Many women provide their babies with the antibodies they will need in the first months of life. The immune system of a fetus isn’t fully activated while it is still in the womb, a likely evolutionary adaptation so that it doesn’t start misguidedly attacking the mother. So, many mothers provide their babies with antibodies through breast milk, which delivers an immunological advantage. Studies show that breastfed babies even have a reduced risk for lower-respiratory infections years later as preschool children.
This whole process of causing more mutations to get a better-fitting antibody can also go horribly wrong—in males, that is. H. pylori can hijack the process of hypermutation and cause epithelial cells that line the stomach walls to unnecessarily mutate, which eventually can lead to gastric cancer. We still don’t know exactly why, but men again seem to be particularly sensitive to this aberrant process.
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IN APRIL 1924, just outside Vienna, a little-known writer was being tenderly attended to by his sister Ottla. The pangs of hunger that had become such a normal accompaniment to his waking hours were getting in the way of his work. But as his condition began to worsen, no matter how hungry he was, there was no way left for him to eat.
Like an Egyptian tomb in the process of being sealed, his esophagus was closing itself off to the world, and most crucially for Franz Kafka, to food. Kafka’s digestive entombment was caused by millions of invisible microbes working their way through his laryngeal tissue. No wonder that the dreaded condition was named “consumption,” as the victims often ended their once vibrant lives as unrecognizable, hollowed-out versions of their former selves.
Tuberculosis (TB) consumes its victims slowly over many years. The disease has wreaked havoc on the lives of humans since the time we began domesticating animals. Mycobacterium tuberculosis, the infectious microbe that has killed millions of humans, is thought to have jumped species from infected cattle to humans some ten thousand years ago in the ancient Fertile Crescent—an area today spanning from Egypt to Iraq. But this isn’t just some disease of the distant past: ten million people today are still infected with tuberculosis worldwide.
This wily microbe grinds down the body’s defenses over time rather than fighting through an acute full-scale microbial attack. Once established, the lifelong chronic infection fights the body’s immunological defenses through a process of attrition. Practically, this means that people who are physically weakened because of diabetes or from fighting another infection like HIV are much more susceptible to TB. This asymmetrical type of microbial battle is weighted in the direction of the attacker, and over time, it leaves those infected systemically withered.
The calling-card symptom of tuberculosis was a white handkerchief stained red from blood-tinged sputum. During the seventeenth through nineteenth centuries, about a quarter of all deaths were caused by TB. The industrial revolution in particular caused millions of people to start coughing up blood (the medical term for this is hemoptysis) from being infected with TB. Many factors contributed to the tuberculosis epidemic in the nineteenth century. Poor ventilation within housing helped spread the infection, a lack of proper nutrition suppressed people’s immunity to the microbe, and even a lack of sunlight reduced the amount of vitamin D produced by the body.*
The classic symptoms of TB were described by Kafka, in a letter to his friend Max Brod, while it insidiously made itself at home in his body. He wrote: “Above all the fatigue increased. I lie for hours in the reclining chair in a twilight state … I am not doing well, even though the doctor maintains that the trouble in the lung has remitted by half. But I would say that it is far more than twice as bad. I never had such coughing, such shortness of breath, never such weakness.”
As the TB kept spreading throughout his body, eventually invading his larynx, Kafka had to chew his food hundreds of times to be able to swallow without gagging. It’s hard to imagine how uncomfortable the last few months of Kafka’s life must have been.
Kafka was forty years old on June 3, 1924, when he eventually succumbed from the complications of tuberculosis. He asked Max Brod to promise not to read or disseminate his unfinished writings but instead to commit them all to the flames. Brod didn’t listen.
As if coming across shards of broken pottery and piecing them back together, Brod assembled chapters and fragments into the completed works he imagined Kafka would have wanted. The