If you’re a microbiologist, the acronym HGT may have you thinking about horizontal gene transfer, the transfer of genes between microbes. But during the months of November and December, HGT takes on a different meaning: holiday gift transfer. As part of the annual #SecretSerratia holiday gift exchange, pairs of microbiologists exchange gifts, usually science and microbiology related.
I eagerly signed up to participate and my Secret Serratia and I swapped gifts and shared photos of our microbial gifts on Twitter, along with ~70 other microbiologists.
Thank you @tera_levin for my #SecretSerratia gift! This will go great with my H. pylori giant microbe (also recently acquired)! pic.twitter.com/0YOkjHdnEr
— Dr. Jennifer Tsang (@jw_tsang) December 7, 2018
But many decades ago, there was a secret serratia of a different nature. The US Navy secretly sprayed Serratia marcescens and Bacillus globigii bacteria over the San Francisco Bay in 1950 (a.k.a. Operation Sea Spray). As part of a large-scale biowarfare test, they were trying to answer questions such as: How far does the bacteria travel and in what amount? And how susceptible are large urban centers to biowarfare attacks?
They had chosen Serratia marcescens because its bright red pigment makes them easy to identify. Many other experiments in the decades preceding also used Serratia as a “tracer organism,” to help map the spread of microbes in different scenarios (ex: talking, during dental work, etc). What none of them knew was that Serratia marcescens, which normally lives in soil and water, is an opportunistic pathogen.
Starting on September 20, 1950, the navy spent six days spraying Serratia marcescens into the air two miles off the California coast. In the days that follow, the military sampled 43 sites to track how the bacteria spread. Turns out, the bacteria spread not only to the city but made their way into the surrounding suburbs. And during this time, residents have inhaled millions of bacterial spores each day.
People started getting sick. Over the next few months, 11 residents were treated at a Stanford University hospital for urinary tract infections. Ten residents recovered but one patient died three weeks later. The Stanford University hospital, which has never documented a Serratia marcescens infection in its history, was the only hospital in the region to document such UTI cases. All cases however were in immunocompromised patients that had indwelling catheters.
This experiment did not become public until 1976, when the Long Island newspaper Newsday, and subsequently,the Washington Post, published reports revealing the biological tests not only in San Francisco, but in the New York City subway system.
During US Senate subcommittee hearings in 1977, the US Army acknowledge that the aerosolized Serratia experiments were conducted at eight locations across the US. In fact, the Army has secretly conducted 239 germ warfare tests from 1949 to 1969.
Then in 1981, the grandson of the patient that died in 1950 sued the US government for allegedly introducing the pathogen to his grandfather. But there also wasn’t any proof concretely connecting the experiments to the infections in San Francisco. The strains isolated at Stanford were not archived nor were they compared to the strain used by the military. Furthermore, no other hospitals in the area saw similar outbreaks.
Hindsight is 20/20. While these experiments were meant to protect society from potential biowarfare efforts, they also came with some unintended consequences. As for the current day Secret Serratia, I’m happy that it comes gift wrap, chocolate, and microbial stuffed animals.
Further reading:
Army Conducted 239 Secret, Open-Air Germ Warfare Tests. The Washington Post, 1977.
Navy Fogged Bay Area With Bacteria. The Washington Post, 1979.
A lot sciency. 😊