Charles Kenny - The Plague Cycle: The Unending War Between Humanity and Infectious Disease

A child isnt too sure about being vaccinated against measles. ( Credit: Not Sure About the Vaccination by Julian Harneis is licensed under [CC BY-SA 2.0] )

The two leading killers worldwide at the start of the twenty-first century are heart attacks and strokes. That is evidence of humanitys greatest triumph: until recent decades, most people didnt live long enough to die of heart failure. Rather, they were felled by a range of infectious diseases that picked off the young or swept through whole populations in pandemic catastrophe.

Covid-19 is a terrible reminder that our victory against infection is far from completeand in all likelihood never will be complete. The cycle of population growth, pandemic, and recovery isnt nearly as violent as it has been in the past, but its still with us. Many more infectious diseases have emerged over the past century than have been eradicated. And the coronavirus has demonstrated the immense costs we bear when people are forced to rely on one of the very earliest responses to infection: running from it.

But although 2020 marked a tragic global reversal, recent progress against infection has been remarkable. In 2015, as I started to think about writing this book, I crowded into a small basement room of the Seattle Westin Hotel with hundreds of doctors, public health workers, and researchers for an event called Lessons Learned on the Path to Eradication. The humbleness of the setting aside, the people who were onstage should be world famous for the contributions theyve made: Jeffrey Mariner, of Tufts University, created a stable vaccine against the cattle disease rinderpest. Pedro Alonso directed the Global Malaria Program at the World Health Organization. Frank Richards, from the Carter Center, battled diseases caused by parasitic worms. Chris Elias, at the Gates Foundation, led his organizations polio eradication effort. And Bill Foege developed the global smallpox eradication strategy rolled out by the World Health Organization in the 1970s.

Of the infectious killers these five speakers worked to stamp out, two have already been driven to extinction, two are on the verge of eradication, and as for the remaining scourge, wiping it out is a real possibility within our lifetimes. In 1980, the smallpox eradication campaign succeeded. Hundreds of millions died of smallpox in the first eight decades of the twentieth century. But since then only one person, a lab technician, has died of the diseaseinfected from an accidental release of a scientific sample. Rinderpest was wiped out globally in 2011, ending a disease that killed millions of cattle owned by some of the planets very poorest households. Rinderpest was also the likely source of the human mass murderer measles. Unchecked, it could have mutated into a species-hopping version once again. The number of cases of guinea worm (a parasite that causes excruciating blisters, vomiting, and dizziness) has fallen by more than 99.9 percent worldwide over the past two decades. As of April 2020, the wild polio virus (which can cripple and kill) had been limited to two countries. And since 2000, thirty-four countries worldwide, including China, Argentina, and South Africa, have made massive strides toward eliminating malaria, cutting death rates by an average of 87 percent.

These and earlier victories have been won through the combined efforts of billions of people. Among them are Lady Mary Wortley Montagu, who popularized variolationthe first effective protection against smallpox; Edward Jenner, who experimented with cowpox to create the first vaccine; Ali Maow Maalin, the last person to contract smallpox outside the laboratory, who spent the rest of his life fighting polio; and Salma Farooqi, who was tortured and killed by the Taliban for the crime of vaccinating children against that same disease.

I would argue that these people are heroes in a worldwide struggle for better health that has seen massive progress in recent decades, but hero and progress are both controversial words in a book that discusses history. The concern is perhaps best illustrated by a review of David Woottons 2006 book Bad Medicine: Doctors Doing Harm Since Hippocrates. Wootton is a historian at the University of York and his Bad Medicine argues that doctors before the twentieth century did little if anything to improve health outcomes of their patients. Wootton offers explanations as to why that was the case. The books reviewer, Harvard historian Steven Shapin, claimed Bad Medicine wasnt history because it documented and celebrated progress, naming heroes. The job of the historian of science, Shapin argued, isnt to judge but to interpret and understand the past in its own terms.

Wootton countered that since both he and Shapin agreed thered been genuine and substantial medical progress, there was nothing wrong in writing a narrative of that progress.