Lydia Rabinowitsch-Kempner was born on 22 August 1871 in Kovno, then part of the Russian Empire and now Kaunas, Lithuania, the youngest of nine children in a prosperous Jewish family. Her father, Leo Rabinowitsch, was a brewery owner; her mother was Minna, née Werblunsky. The household valued education, and the children were expected to study at university. That path was closed to her at home. In the Tsarist empire, women and Jews faced legal barriers that made advanced scientific training nearly impossible. After attending the girls’ gymnasium in Kovno and studying Latin and Greek privately, she left for Switzerland in 1889, one of the few places in Europe where women could pursue university degrees.
She studied natural sciences at Bern and Zurich, concentrating on botany and zoology. In 1894 she received her doctorate at Bern, summa cum laude, with a dissertation on the developmental history of the fruiting bodies of certain gasteromycetes, a mycological subject far from the work that would later define her name. The same year she went to Berlin and entered the Institute for Infectious Diseases directed by Robert Koch. She was the first woman to work there as a researcher. The appointment was unpaid, a pattern that would follow her for decades. Koch’s institute was then the world’s leading center for bacteriology, and tuberculosis was its great subject. Rabinowitsch learned laboratory methods at the source and turned from fungi to microbes that killed people.
From 1895 to 1898 she taught bacteriology at the Woman’s Medical College of Pennsylvania in Philadelphia. She rose from lecturer to professor and founded a bacteriological laboratory there, returning each summer to Koch’s institute. In 1896 she addressed the International Congress of Women in Berlin on medical study by women in different countries. In 1898 she married Walter Kempner, a physician and fellow researcher at the Berlin institute. Contemporary reports noted that they married during an international medical congress in Madrid. She declined to remain in the American professorship and returned to Berlin.
The couple had three children: Robert, born in 1899, later a lawyer and a United States prosecutor at the Nuremberg trials; Nadeshda, or Nadja, born in 1901, who studied Anglo-American literature and died of tuberculosis in 1932; and Walter, born in 1903, who became a physician. Family life and laboratory work ran together. Walter Kempner eventually practiced medicine to support the household while Lydia continued unpaid research. In 1899 they studied malaria near Lake Scutari in Montenegro. She later investigated plague in Odessa and malaria in what is now Albania.
Her decisive scientific work concerned tuberculosis and milk. Koch had argued that bovine tuberculosis was of little importance to humans. Rabinowitsch-Kempner disagreed and pursued the question in the products of Berlin’s large dairy firms, especially the Bolle dairy. As early as the mid-1890s, and with a widely noted demonstration in 1904, she showed that tubercle bacilli could be present in raw cow’s milk and that this was a real route of infection, including for infants fed so-called nursery milk. The finding produced a public scandal before it produced reform. After resistance, pasteurization and safer handling were developed in cooperation with the dairy industry. The work made her a recognized authority on tuberculosis transmission and public hygiene. She published widely, spoke at congresses in London, Paris, Rome, Moscow, and elsewhere, and in 1904 presided over the hygiene and bacteriology section at the scientists’ meeting in Breslau.
In 1903 she left Koch’s institute, reportedly after male colleagues refused to collaborate with her, and moved to the Pathology Institute of the Charité under Johannes Orth. She remained there as an unpaid scientific assistant for many years. In 1912 Kaiser Wilhelm II conferred on her the title of professor. She was the first woman in Berlin and the second in Prussia to receive it, after the zoologist Maria von Linden. The title carried honor but not a university chair, a salary, or the right of habilitation, which Prussian universities still denied women. She was a professor without a professorship.
Around 1913 or 1914 she became editor of the Zeitschrift für Tuberkulose, the first woman to edit a major medical specialist journal. After her husband’s death from laryngeal tuberculosis in 1920, she finally obtained a paid post as director of the bacteriological and serological institute at Berlin’s municipal Hospital Moabit, a position she held until 1934. She was active in women’s organizations, helped found groups that offered interest-free loans to female students, and was made an honorary member of the Bund Deutscher Ärztinnen even though she was not a licensed physician in the ordinary clinical sense. She was listed among the notable figures of Berlin society.
The Nazi seizure of power ended her public career. In 1933 and 1934 she was stripped of offices and honors and forced into retirement because she was Jewish. She could no longer edit the tuberculosis journal. Her sons left Germany with help from American friends; she remained in Berlin. She had already seen the political weather change. Her son Robert later recalled that when the first swastika flags appeared in the streets she wept in the car and said a pogrom was beginning. She died in Berlin on 3 August 1935 after severe illness, including heart disease and breast cancer, a few weeks before her sixty-fourth birthday. She was buried in the Parkfriedhof in Lichterfelde.
Her life concentrated several contradictions of German science before 1933. She worked beside Robert Koch and in some practical questions of milk-borne tuberculosis went further than he did. She held an American professorship in her twenties and a Prussian professorial title in middle age, yet for most of her career she was unpaid. She raised three children while running laboratories and editing a journal. She converted from Judaism to Protestantism around the time of her marriage, but Nazi racial law still defined her as Jewish and expelled her from the hospital she had directed. Tuberculosis, the disease she spent her life studying, killed her husband and her daughter.
What remains is a record of laboratory persistence applied to a public health problem that affected ordinary households every day. Raw milk was a vehicle of infection; she proved it and helped force a change in how cities treated a staple food. She was among the first women to occupy the institutions of German bacteriology and among the first to lose those places when those institutions were captured by racial politics. A street near Berlin’s main station now bears her name, and memorials at Moabit recall the Jewish physicians who worked there. The larger story is simpler: a scientist from Kovno who used the methods of Koch’s school to show that tuberculosis could travel in a milk bottle, and who paid, in money, status, and finally exile from her own laboratory, for being a woman and a Jew in the Germany of her time.