Respiratory isolation for tuberculosis

Tuberculosis has been recognized for thousands of years, and its story reflects the evolution of medicine itself. In the early Hippocratic corpus of the 5th–4th century BCE, chronic wasting lung diseases—likely including tuberculosis—were grouped under phthisis, meaning “to waste away.” The Hippocratic school believed the illness to be hereditary, a view shaped by its appearance among cohabitating family members. The idea of contagion surfaced in Classical Greece: Isocrates acknowledged possible transmission, while Aristotle noted that scrofulous disease in livestock could spread through “foul air.” Galen, writing in the second century BCE, leaned toward a contagious explanation and recommended treatments such as fresh air, milk, and sea voyages. Yet physicians in the Galenic tradition largely favored the miasma theory—the belief that disease arose from inhaling noxious vapors—so individuals with phthisis were not stigmatized during Greek and Roman times.

By the Middle Ages, scrofula had gained a new cultural identity. Known as the “king’s evil,” it was believed curable by the royal touch of English and French monarchs, and sufferers were sometimes treated like lepers. A shift in thinking emerged toward the end of the 18th century, when physicians encouraged patients with advanced disease to remain at home, emphasizing diet, gentle physical exercise, and fresh air rather than long, arduous journeys to coastal spas or dry climates.

The sanatorium era began in 1859, when Herman Brehmer opened the first tuberculosis sanatorium in Gobersdorf, in the Silesian Mountains. These institutions originated as therapeutic rather than public health responses. Mountain air was thought to have curative power, and Brehmer believed that TB patients had abnormally small hearts; he theorized that high-altitude air would strengthen the heart and improve health. The model spread internationally. In the United States, Edward Livingston Trudeau—himself diagnosed with tuberculosis in the early 1870s—opened the nation’s first sanatorium at Saranac Lake in 1884. The first patients were housed in the modest “Little Red” cottage, and Trudeau credited the restorative Adirondack climate with extending his life until 1915.

Even as sanatoria expanded, the scientific understanding of tuberculosis advanced dramatically. In the Islamic Golden Age, Avicenna (980–1037 CE) described phthisis as contagious and recommended isolating patients. During the Renaissance, Girolamo Fracastoro (1478–1553 CE) proposed an early germ-like theory, suggesting that diseases spread through tiny “seed-like” particles. But it was not until the 19th century that definitive evidence emerged. Inspired by Pasteur’s work, Jean Antoine Villemin demonstrated in the 1860s that tuberculosis was infectious, though he could not yet identify the organism responsible. The breakthrough came on 24 March 1882, when Robert Koch announced his discovery of the tubercle bacillus—Mycobacterium tuberculosis—and established its role through what would become known as Koch’s postulates. His work also confirmed that the disease spread directly between people via airborne droplets.

Diagnostic techniques improved quickly. Paul Ehrlich refined Koch’s staining methods, and later modifications by Ziehl and Neelsen produced the famous acid-fast stain still used in much of the world today to identify tuberculosis in sputum samples.

The mid-20th century brought the true revolution: effective antibiotic therapy. In 1941, Jörgen Lehmann, working with the Swedish firm Ferrosan, showed that para-aminosalicylate (PAS) inhibited tubercle bacteria and protected infected animals. That same year, Selman Waksman and Albert Schatz at Rutgers University isolated streptomycin from Streptomyces griseus, demonstrating its lifesaving potential in both animal models and humans. Sanatoria continued to operate into the 1960s—mainly to prevent relapse—but their importance waned rapidly with the arrival of powerful drug combinations. The discovery of isoniazid in 1952 allowed near-universal cures when given alongside streptomycin and PAS. Additional breakthroughs soon followed: rifampicin in the mid-1960s, and recognition of pyrazinamide’s sterilizing activity in the early 1970s, enabling the fully oral six-month regimen that remains the standard for treating drug-susceptible TB today.

To bridge the gap between clinical efficacy and real-world adherence, public health programs adopted directly observed therapy (DOT), in which patients take medications under supervision to ensure consistent, effective treatment. This approach, used worldwide, helps prevent relapse and reduces ongoing transmission in the community.

Source: Karakousis, P.C. and Mooney, G., 2025. Respiratory isolation for tuberculosis: a historical perspective. The Journal of Infectious Diseases, 231(1), pp.3-9.