Postcard art shows people reacting with disgust as a person in a shop sneezes openly.

Airborne Infection Control in 20-Century Peace and War

By Tom Quick ~

The world can change unexpectedly in times of crisis.

This story begins, like so many histories of medicine, with an illness. In the archives of the National Library of Medicine (NLM) the papers of microbiologist Theodor Rosebury include the following autobiographical recollection, of his wartime service with the Biological Warfare Center at Detrick Field (soon to be known as Fort Detrick):

“On a beautiful evening in May 1945—the 25th—Martin, Jerry and I, after having a drink in the officers’ club in the evening, took the bus from the camp into Frederick [MD] to have dinner at the Buffalo… a smallish and not particularly elegant restaurant with high-backed dark pine booths. One of its specialities was broiled lobster… I think it was probably as good as ever that night: and Jerry and Martin ate it with obvious relish; but I had trouble getting it down.”

Later that night, Rosebury took a turn for the worse:

“The luminous dial on my bedside alarm clock said a little after two when I awoke with a start, thinking of nothing but lobster. The beast seemed to have put itself together inside my stomach, grown a new shell and spiny claws, and was desperately struggling to make its way to freedom by the shortest possible route… the feeling of nausea which had been slight before was now almost, but not quite, enough to make me think of vomiting. And I felt unseasonably cold.”

A simple case of food poisoning perhaps? Not quite: the lobster would prove innocent. Yet the next day, Rosebury developed an additional set of symptoms: chills, a progressively worsening headache, fever, and more general nausea. As he would soon find out, he had contracted an unusual disease: the highly infectious and potentially life-threatening psittacosis, or ‘parrot fever.’ The following two weeks would determine Rosebury’s fate.

The Airborne Infection Hypothesis

During the 1930s, a new conception of bacterial contamination had begun to gain ground in American epidemiological science: that of airborne infection. The ancient notion that disease could be caused by ‘bad air’ had been broadly discredited by this time, in large part by the bacterial (and later viral) conception of disease transmission. Yet the airborne infection hypothesis gave new life to the idea of unhealthy air. Whereas earlier models of atmospherically-caused affliction had mainly focused on the qualities of the air itself, airborne infection theorists argued that the atmosphere carried microscopic pathogens on a far greater scale than had previously been recognized.

A photograph of a man sneezing.
In Aerobiology, 1942
National Library of Medicine #23610410R

The idea gained significant military attention due to its implications for the weaponization of microscopic life. The prospect of infectious agents hanging suspended in the air suggested that whole populations might be in danger from nefarious mists or sprays cast over them. The increasing ubiquity of airplanes in the theatre of WWII combat made this especially frightening.

In part prompted by a parallel British research program, American military leaders soon decided that they had to investigate all aspects of biological weapons, and especially the possibility of airborne attack. By 1942, a dedicated site for research into deadly infectious agents was created at Detrick Field, which would become the principal US site for bioweapons research.

Fears relating to biological weapons were not confined to the military during the early 1940s. In his role as a bacteriologist and lecturer on public health at Colombia University, Rosebury had been at the forefront of civilian scientific concern as to the possible threat posed by airborne pathogens.

Recovery and Discovery

Theodor Rosebury had been recruited to Detrick in the fall of 1942. In the weeks before his illness, he had experimented with infecting mice with psittacosis in highly specialized air chambers designed to mimic the conditions that a biological attack from the air might produce. After handling a defective vial of the pathogen, a tiny amount of pure psittacosis culture had squirted onto his hand. In what was likely an act of misguided wartime bravado, he had assumed he had escaped infection, and neglected to report the exposure to his superiors. Now, a week or so later, he was lying in an isolation room, his body fighting an exotic, infectious, and often deadly disease.

In addition to being isolated in the medical ward of his barracks, Rosebury was treated with two of the most important infection control agents of the war: one of the sulfa drugs, and the just-developed penicillin. He remembered his experience as follows:

“caution directed that I be given sulfadiazine and penicillin… This double therapy was a form of double jeopardy. Sulfadiazine could be given by mouth, by rigid protocol every four hours. Penicillin was then for intramuscular use only, and by equally rigid routine was jabbed into my buttock every three hours… I got worse during the first few days but never felt desperately ill… [my chart from the time] shows fever spiking above 103°… and then falling to normal and staying there. This implies a response to therapy too prompt to be thought coincidental.”

It seemed likely, Rosebury concluded, that he was “the first person to show so definite an effect of penicillin on psittacosis.”

After his recovery, Rosebury conducted studies into the mechanism of airborne infection. He designed an experiment to establish just how this pathogen had transferred from a seemingly minuscule leak of material on the palm of his hand, into the Detrick laboratory air, and from there into his lungs. It appeared that the leak had occurred through a tiny defect in the glass of the vial, caused by a hole just wide enough to admit a human hair. Using the same bottle, Rosebury and his colleagues recreated the incident using a harmless but easily detectable indicator organism in place of psittacosis itself. By ejecting the same tiny amount of liquid onto Rosebury’s hand under controlled conditions, but this time with bacterial samplers placed at intervals between 8 and 35 inches from the faulty vial, they demonstrated that it was possible for a small ‘cloud’ of infected particles to bounce off a hand and enter the atmosphere. Using the latest stroboscopic imaging techniques (developed under Harold Edgerton at MIT), they were even able to photograph droplets bouncing up from Rosebury’s palm and into the laboratory air. Only a few years earlier, these same techniques had been used to produce the first high-definition images of the airborne spread of droplets from coughs and sneezes: images that we are all extremely familiar with today.

For Rosebury, his experience of wartime research emphasized the destructive potential of biological warfare: as a founding member of the Pugwash Conferences dedicated to opposing nuclear and other weapons of mass destruction, he would spend the rest of his life campaigning against the development and production of all biological weapons.


The success of Rosebury’s penicillin treatment was being replicated in much more widespread efforts to combat infections of all kinds Beginning with the sulfa drugs, physicians increasingly looked not to prevent the transmission of pathogens between bodies per se, but rather to the elimination (or at least radical reduction) of those pathogens once they had entered a host organism. This approach displaced an earlier focus on attempts to ‘clean’ the air using chemical mists and even ultraviolet light. Yet the prospect of combatting the spread of airborne droplets in sites such as hospitals, schools or transportation systems seemed less pressing in a world in which many pathogens could be effectively combatted inside the bodies of patients, using antibiotics: the crisis of infection management and the perceived biological weapons threat during WWII combined to change the way in which airborne infection was managed and understood.

A man walking in profile in a gallery.Tom Quick, PhD, is a Research Associate in the Centre for the History of Science, Technology and Medicine (CHSTM) at The Univeristy of Manchester and a 2019 NLM Michael E. DeBakey Fellow in the History of Medicine.

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