For Disability History Month, Kip Heath delves into Florence Seibert’s lifelong fight against infectious diseases.
“It never dawned on me that I was ever going to be considered important”, said American biochemist Florence Seibert as she reflected on her life in an interview the year before she died in 1991. It may never have dawned on her, but Seibert was responsible for developing the tuberculin purified protein derivative (PPD) that is still one of the most important medicines in controlling tuberculosis infection today.
Born in Pennsylvania in 1897, Seibert had first-hand experience of the serious impact of infectious diseases. While playing with her siblings, aged 3, Seibert and her elder brother contracted polio. They both survived the disease but Florence Seibert faced lifelong complications. She learned to walk again through the use of braces but was left with a permanent limp.
As an adult Seibert didn’t treat her disability as a setback, saying that because she was disabled, “I couldn’t go out to dance or play, and so I stuck to things that were supposed to be done.” She excelled at them. Despite concerns from family that her disability would hold her back, Seibert received a scholarship to Gaucher College in Maryland with an initial aspiration to study medicine at John Hopkins. She changed paths and earned a PhD in physiological chemistry from Yale University in 1923 where she identified that bacterial contamination in vaccines were inducing fevers and developed a method to distil the water to prevent the contamination.
The biggest part of Seibert’s work focussed on tuberculosis. Today, it is estimated that 25% of the world’s population has been infected with tuberculosis and that 5-10% of those infected will eventually develop symptoms. Being able to identify and treat people who have been infected is essential in controlling the spread of the disease.
When Seibert started work on tuberculin in the 1930s, Robert Koch had identified that Mycobacterium tuberculosis caused tuberculosis disease and had discovered that injecting his ‘old tuberculin’ into a patient’s arm would produce a reaction if they had been infected with tuberculosis. But the test was unreliable and produced false negatives. Several scientists had worked on this process, including Charles Mantoux who developed the intra-dermal technique that is still used today.
Seibert was the first person to correctly identify and successfully purify the protein that triggers an immune response during a tuberculosis infection. This work meant that Seibert was able to produce large quantities of the tuberculin purified protein derivative (PPD) that was responsible for making the Tuberculin Skin Test reliable and standardised.
Seibert never sought a patent for her purification process, and it was adopted by the United States government in 1941 as a cheap and quick way to test if someone had been infected with tuberculosis. It took until 1952 for this method to be adopted by the World Health Organisation. By the 1960s, Seibert’s method was the global standard and 72 years later, Seibert’s tuberculin PPD is still listed on the World Health Organisation’s essential medicine list.
Florence Seibert lived to see her work recognised when, the year before she died aged 93, she was inducted into the US Women’s Hall of Fame.
This post has been written as part of the Reclaiming narratives: ScienceWrite blog series which highlights the lives and achievements of extraordinary scientists from minoritised groups.
