Biological warfare, or “germ warfare,” is the “use of biological toxins or infectious agents (bacteria, viruses, and fungi) with the intent to kill or incapacitate humans.” Historically, the US’ involvement in bacterial weaponry has been driven by competition and paranoia.

In 1942, President Roosevelt signed into action the first biological warfare program; backed by the National Academy of Sciences

A government body -- the War Research Service (WRS) -- was created to oversee these activities, and George W Merck (of the #Merck Pharmaceutical Company) was appointed to leadership.

"Work in this field cannot be ignored in a time of peace,” Merck warned officials. “It must be continued on a sufficient scale to provide an adequate defense.”

A Committee on Biological Warfare was established in 1948. When a subsequent report determined that the US was “particularly susceptible” to attacks, a series of “open air tests” were ordered. The purpose? To simulate the effects of a realistic biological warfare attack.

With a plan in place, a task force was sent to unleash bacteria on San Francisco.
“Special Report No. 142: Biological Warfare Trials at San Francisco, California, 20-27 September 1950”

Nowhere in the report was the welfare of San Franciscans mentioned; the tests proceeded without knowledge or consent from the public.

The U.S. Army was deployed to San Francisco and began secretly showering the city with bacteria. Over a course of eight days, a ship puttered along the shoreline of the bay, releasing massive clouds of two different pathogens -

In total, six “experimental warfare attacks” were carried out: four with Bacillus globigii, and two with Serratia marcescens.
#SanFrancisco

The Army blasted these chemicals in 30-minute spurts, producing huge clouds up to two miles in length, then proceeded to collect and assess dozens of samples a various collection spots across the city.

As noted in the report, various aspects of each of the six tests were scrupulously monitored -- the time, the temperature, the wind speed, the humidity -- but the most important factor seemed to be brushed over: the well-being of the people being sprayed

According to L. J. Cole, author of Clouds of Secrecy, it was quite a bit:
" In other words, nearly every one of the 800,000 people in SF exposed to the cloud at normal breathing rate inhaled 5000 or more particles per minute during the several hours that they remained airborne.”

The Death of Edward Nevin
A month prior to the Army’s tests, a 75-yo man named Edward Nevin checked into a SF hospital to undergo a prostate surgery. After he was released & two days after the Army’s tests, Nevin contracted a urinary tract infection and fell gravely ill.

Over the next six months, 10 more patients were admitted with infections caused by Serratia marcescens (all of whom later recovered after long, painful hospital stays)

An article in the American Medical Association’s Archives of Internal Medicine exploring the facts: 11 patients infected over 6 months, aged 29-78, all with urinary tract infections caused by Serratia marcescens.

Historically, Serratia marcescens had no record in San Francisco -- or California, for that matter.

The medical paper did not go unnoticed: when the government read it and realized that they’d caused a bacterial outbreak, they reeled to cover their tracks.

For 25 years, the government’s involvement in biological warfare testing -- and its use of civilians as unwitting guinea pigs -- remained top-secret. It’s a secret that likely would've gone on indefinitely if not for the efforts of a savvy Newsweek reporter named Drew Fetherston

In November 1976, Fetherston exposed a number of biological tests performed in major cities by the Army and the CIA.

George H. Connell, Centers for Disease Control:

“There is no such thing as a microorganism that cannot cause trouble. If you get the right concentration at the right place, at the right time, and in the right person, something is going to happen.”

San Francisco’s incident was just one of 293 bacterial attacks staged by the United States government between 1950 and 1969. It was neither the most heinous, nor the deadliest.

Serratia marcescens, the bacteria sprayed over San Francisco, has since been declared hazardous. “It can cause serious life-threatening illness,” wrote the FDA in 2005, “especially in patients with compromised immune systems.”

To learn more about other biological warfare testing in the U.S., refer to Leonard J. Cole's incredibly well-researched history, Clouds of Secrecy.