March 24 is World TB Day, Hail Robert Koch

Today is World TB Day and a good time to reflect on the many contributions of Nobel Prize winner Robert Koch (1843-1910), a poor country doctor in Germany who astounded the world on this day in 1882 by announcing he had discovered the cause of tuberculosis. At the time, TB was raging across Europe, killing one in seven people.

Koch is credited with turning bacteriology into an exact science, and his achievements are all the more impressive considering that he had a full-time medical practice, his lab was his four-bedroom flat, and his main piece of equipment was a microscope that his wife bought after scraping together the money. Working in remote Wallstein, in the Posen Province, Prussia, he was largely cut off from scientific libraries and contemporaries. In spite of his isolation — or perhaps because he was not shackled by conventional wisdom — he followed his hunches through painstaking work, and changed the course of medicine.

His first breakthrough was to prove that anthrax is caused by the anthrax bacillus — a year before his contemporary, the French microbial superstar Louis Pasteur, did so. To say Koch’s lab was makeshift is an understatement. To inoculate mice with anthrax bacilli taken from the spleens of farm animals that had died of the disease, he used home-made slivers of wood.

He further went on to prove that the bacilli could lay dormant and grow again under the right conditions. To do this, he obtained pure cultures of the bacilli by growing them on the aqueous humour of the ox’s eye.

In 1882, he announced that he had discovered the tubercle bacillus and also a method of growing it in pure culture — which opened the door to diagnosis and treatment.

Koch was also the scientist who discovered the vibrio that causes cholera, and made significant contributions in the understanding and control of rinderpest, malaria, blackwater fever, surra of cattle and horses and plague. Last year the UN declared that rinderpest, a deadly disease that affects cattle, had been eliminated — the only disease other than smallpox that humans have succeeded in wiping off the face of the earth.

Tuberculosis, on the other hand, remains a serious human threat, with 9 million new cases each year and 1.7 million deaths. As Bill Gates points out on his blog, one of the biggest problems is outdated tools. The most common TB test is 125 years old and most TB therapies are 40 years old and take six months to work. Symptoms are often misdiagnosed or not caught early, which allows patients to unwittingly spread the infection, creating an endless cycle and contributing to drug resistance.

“Fortunately,” Gates says, “there is a promising pipeline of new TB diagnostics, drugs and vaccines under development.” These include a new molecular test, GeneXpert, which can accurately determine whether a patient has TB in about two hours.

The challenge is to make molecular diagnostics as affordable as home-made slivers of wood.





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