Using DDT to Fight Polio was a Mistake, but Learning from it was Valuable

Many Americans have run out of patience with mitigation methods for minimizing the spread of the coronavirus. But the forgotten story of how Americans once resorted to spraying a now-banned pesticide, DDT, to combat polio is a reminder of how desperation can cloud judgment — and how only trial, error, patience and time can produce true epidemic control.

In summer 1944, polio arrived in the Piedmont area of North Carolina, causing an especially devastating outbreak. It attacked the victims’ nervous system, infecting mostly children. It paralyzed the sickest ones, leaving the worst off — if they survived — unable to walk or breathe on their own. Towns in the area quickly shut schools, parks, theaters, playgrounds and pools. Parents kept their children close.

While other areas, like New York City, had weathered larger outbreaks, the rural foothills was quickly overwhelmed. The region’s one hospital couldn’t handle the constant flow of patients. The polio philanthropy March of Dimes, along with the Army and Red Cross, rushed in doctors, nurses and therapists and set up a makeshift hospital with army tents. Eventually, relief came thanks to polio’s seasonality. By autumn, the epidemic subsided, and early in 1945, the emergency hospital came down.

But many feared polio would be back. After all, by the mid-1940s, polio had been returning to the United States each summer with wearying regularity. California had even seen three epidemics in a row. In spring 1945, desperate to prevent another outbreak, Piedmont residents endorsed a suggestion from a local reverend: towns in that area of North Carolina should be sprayed with DDT.

World War II had just ended in Europe, and every American had heard about the wonder chemical that helped the Allies to victory. DDT had protected troops from a long list of insect-carried diseases: malaria, dengue, yellow fever, typhus, bed bugs, scabies and more. And while no one then knew precisely how polio spread, one popular theory blamed flies.

Plenty of evidence seemed to support the theory. Scientists had found the polio virus in privies — where flies congregated — and on flies themselves; they had also documented flies spreading the disease among lab primates. During Piedmont’s 1944 outbreak, a team of revered polio scientists led by Yale University biologist John Rodman Paul had collected fly-contaminated food from the homes of polio patients and then showed that the food gave primates polio-like symptoms, too.

It wasn’t proof that flies spread polio, but it seemed to point in that direction.