Fifty years ago: Dr Jonas Salk administers the early form of polio vaccine (Picture courtesy: USIS)

For much of the first half of the 20th century, polio conjured up every parent?s worst nightmare: children who could not walk without steel braces; others imprisoned in large tank respirators called iron lungs, gasping for every breath. Still others died. But on April 12, 1955, Americans learned that Dr Jonas Salk had developed a safe and effective vaccine against polio. Thanks to successful immunisation programmes in the decades since, parents today can rest easy knowing that polio is preventable and rare.

Marking the 50th anniversary of the vaccine are two new books and several exhibits that re-examine this remarkable chapter in the history of American medicine, including celebrations at the University of Michigan, where the vaccine trial was conducted and its efficacy was announced 50 years ago, and at the University of Pittsburgh, where Salk did his research.

In Splendid Solution: Jonas Salk and the Conquest of Polio, published by Putnam, Jeffrey Kluger writes about how Salk became an international celebrity. Kluger, a senior writer for Time magazine, describes the aggressive, often bitter rivalry between Salk and another virologist, Dr Albert Sabin. Even though Salk?s vaccine, an injection made from killed virus, was developed first and is the vaccine most often used in the US today, it was derided by many virologists as a stopgap measure that was superseded by Sabin?s oral vaccine, made from live-attenuated virus and introduced in 1963.

The first major American epidemic of polio, or infantile paralysis, began in June 1916. New York was hit especially hard, with more than 9,000 cases and 2,343 deaths. Jonas Salk was 20 months old at the time, and as Kluger recounts, his mother, Dora, kept him and their Manhattan apartment scrupulously clean, in the belief that doing so would protect against polio.

In the four decades that followed, doctors struggled to prevent and treat the mysterious disease. During epidemics, which typically occurred in the summer, movie theatres and swimming pools closed and public libraries disinfected their collections.

In Polio: An American Story, published by the Oxford University Press, David Oshinsky, a historian at the University of Texas, describes how the National Foundation for Infantile Paralysis revolutionised the enterprise of medical research in the US. The foundation started long-term research grants, as well as indirect financing to support universities where researchers were based, and required those who received its grants to share their ideas with other scientists ? all essential elements of medical research today.

Polio was not limited to children, though they were the epidemiological focal point of the disease and the selling point of the crusade for a cure. The most famous adult polio patient was President Franklin D. Roosevelt, who was infected at 39 and used a wheelchair for the rest of his life. In 1937, Roosevelt and his former law partner, Basil ?Connor, started the infantile paralysis foundation or, as it came to be known, the March of Dimes, to conquer and treat polio.

The foundation became the gold standard for philanthropies devoted to eliminating diseases, and it pioneered fund-raising techniques like national publicity campaigns, celebrity endorsements and donation canisters featuring attractive children.

In his book, Oshinsky notes that the public?s fear of polio often outweighed its actual threat. In many of the worst epidemics in the US, 30,000 people or fewer contracted the disease, a far lower number than the annual incidence of other childhood killers now contained by vaccines, like measles, diphtheria and whooping cough.

Eighteen years passed between the establishment of the foundation and the completion of the complex trial on 1.8 million children that confirmed Salk?s vaccine as safe and effective. For many, the presumed conquest of polio helped create the expectation that well-financed, well-executed medical science could cure all that ails us.

Sadly, polio cannot yet be relegated to history. Last year, 1,263 cases were diagnosed, primarily in the polio-endemic nations of Nigeria, India, Pakistan, Niger, Afghanistan and Egypt. Polio is mainly transmitted by faecal-oral contact; about one infection in 200 leads to irreversible paralysis, usually in the legs. (NYTNS)