In 1847, the Hungarian physician Ignaz Semmelweis made a pivotal observation while working at the Vienna General Hospital. He identified a stark correlation between the incidence of puerperal fever—a fatal infection affecting women following childbirth—and the practices of medical staff. Semmelweis noted that mortality rates were significantly higher in wards where doctors and medical students performed examinations immediately after conducting autopsies without sanitising their hands. He theorised that these practitioners were inadvertently carrying cadaverous particles from the morgue to the maternity wards, thereby transmitting disease to the patients.

To address this, Semmelweis introduced a mandatory policy requiring medical staff to wash their hands in a solution of chlorinated lime before examining expectant mothers. The results were immediate and dramatic, with the mortality rate in the affected wards plummeting from approximately 18 per cent to less than 2 per cent within a matter of months. Despite this compelling statistical evidence, his findings were met with widespread scepticism and professional hostility from the medical establishment of the time, which struggled to reconcile his ideas with the prevailing miasma theory of disease.

The resistance to his work was rooted in the fact that the medical community had not yet embraced the germ theory of disease. Because the existence of microscopic pathogens remained unproven and poorly understood, many physicians found it difficult to accept that their own hands could be the vectors of infection. Consequently, Semmelweis struggled to gain broad support for his hygiene protocols during his lifetime, and his revolutionary insights were largely sidelined by his contemporaries.

It was only in the decades that followed, as the work of scientists such as Louis Pasteur and Robert Koch established the foundations of modern microbiology, that the significance of his observations was fully realised. His pioneering efforts in infection control are now recognised as a cornerstone of clinical practice, demonstrating the profound impact of simple sanitary measures on patient safety.

• Identified the transmission of puerperal fever via medical staff.
• Implemented mandatory handwashing with chlorinated lime in 1847.
• Achieved a dramatic reduction in maternal mortality rates.
• Faced significant professional opposition due to the lack of germ theory.
• Established a foundational principle for modern antiseptic practices.