To most people, human excrement is nothing more than a smelly afterthought.
But for public health experts, it's quickly becoming a valuable tool in the fight against disease.
Last month, scientists from the University of Denmark published a study suggesting that human waste taken from airplane toilets could be used to produce richly detailed pictures of where specific strains of bacteria and viruses reside and spread.
Sifting through people's feces, the thinking goes, could be a way to monitor global diseases in real-time. Better yet, the technique would be faster than the current public health monitoring tools, which typically rely on self-reports that are slow and unreliable.
Globally, infectious diseases account for roughly 22% of all deaths.
Contaminated drinking water and unsanitary conditions are the most visible ways bacteria invade people's bodies. But simply not washing your hands can also lead to infectious disease. The resulting infections cause many people to suffer deaths that could've easily been prevented.
In the latest research, the Danish scientists found distinct regional patterns in airplane poop bacteria's country of origin. Looking at 18 flights servicing nine cities, they managed to get a small picture of how bacteria populations differ around the world.
Though they can't generalize the findings to the billions of people around the world, the study does offer promise as a clever trick of data collection. The team's proof-of-concept suggested some early patterns that need further testing:
- In South Asian samples, bacteria responsible for antimicrobial resistance were far more common than they were in North American samples.
- Researchers also found a difference in strains. In South Asia, it was more common to find norovirus and Salmonella enterica, a bacterium that can grow on poultry and in unpasteurized milk. In large amounts, it can cause vomiting, diarrhea, and fever.
- In North America, meanwhile, samples tended to show a greater presence of Clostridium difficile. Generally, C. diff is acquired in hospitals and nursing homes; it is often resistant to antibiotics and can cause life-threatening infections.
The ultimate goal: finding something terrifying in human waste before it spreads to epidemic proportions. Data is only useful if it's found — and used — before a catastrophic outbreak occurs.
In that pursuit, other researchers outside Denmark have begun their own creative searches.
At MIT, scientists are tracking the spread of pathogens through Cambridge, Massachusetts, using the city's sewer system. When tested, samples of sewage can reveal illicit drug use and evidence of the community's health.
Nearby, scientists from Boston's Children Hospital and Harvard Medical School are using Wikipedia to track flu outbreaks. A study published last year suggested the articles people searched for using the online encyclopedia beat out Google Trends and even the model used by the Centers for Disease Control and Prevention in spotting flu patterns.
To be clear, scientists still need more time to elucidate the specific origins of certain bacteria if they ever hope to track outbreaks on a person-by-person level. That means being able to tie the DNA sequences of individual bacteria to specific disease outbreaks.
"Global spread of antimicrobial resistance in bacterial pathogens is another major threat against human health," the Danish researchers wrote in their report, "yet we don't know much about how these genes travel and spread worldwide."
In an ideal world, siphoning poop from airline toilets will come to be seen as a noble and important first step in reaching that end goal.
